Eggshell in Artistic and Alchemical Recipes: Late Antiquity to ...

Eggshell in Artistic and Alchemical Recipes: Late Antiquity to 1800

MA Thesis

Timothy Greening

Student number: 11701706

Conservation and Restoration, specialization Technical Art History

University of Amsterdam, Amsterdam

Thesis supervisor: Dhr. dr. A.R. de Koomen

Second reader: Dhr. dr. H. den Otter

21 June 2019


Greening, University of Amsterdam 2019

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Table of Contents Acknowledgements .................................................................................................................................. 2

Summaries ................................................................................................................................................ 3

English .................................................................................................................................................. 3

Nederlands ........................................................................................................................................... 4

Introduction ............................................................................................................................................. 5

Chapter 1: Calcium Carbonate Pigment Group: Chalk, Seashell and Eggshell ......................................... 9

Chapter 2: Eggshell Pigments: An Overview .......................................................................................... 14

Chapter 3: Alchemical Calcination ......................................................................................................... 17

Written Sources .................................................................................................................................. 17

Illustrations ......................................................................................................................................... 20

Modern Scientific View ...................................................................................................................... 25

Chapter 4: Eggs and the Alchemists ....................................................................................................... 30

Written Sources .................................................................................................................................. 30

Illustration .......................................................................................................................................... 31

Modern Scientific View ...................................................................................................................... 33

Chapter 5: Recipes: Artist and Alchemist ............................................................................................... 36

Lazur and the Arabs ............................................................................................................................ 36

Eggshell White and Alchemy? ............................................................................................................ 37

Eggshell Membrane: Observations .................................................................................................... 40

Discussion and Final Conclusions ........................................................................................................... 44

Appendix I: Investigating the Translation of a Recipe Source ................................................................ 46

Appendix II: Modern Eggs, Historic Reconstructions? ........................................................................... 49

Bibliography ........................................................................................................................................... 50



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Acknowledgements First, I would like to thank Arjan de Koomen for his supervision of this thesis.

Thank you also to my instructors Maartje Stols-Witlox, Erma Hermans, Rene Peschar, Maarten van

Bommel, Ella Hendricks and Abbie Vandivere.

I would also like to thank Herman den Otter for being the second reader of this thesis.

A deep thanks is due to my family for their support, without which this thesis could not have

happened.

Secondly, a thank you is due to all my C&R classmates for their comradery and support over the two

years. In addition, I greatly appreciate Karina Foppele and Suzanne Bul for taking the time to send

some eggshell recipes to me, in translation from Dutch. An additional thank you goes to Julia Wagner

for help with some German text interpretation. Also, a thanks to Marieke Hendriksen from the

ArtTechne project for some thoughts about alchemy and kilns. I would also like to thank Professor

Lawrence Principe at Johns Hopkins University for the comments about alchemical calcination.

Finally, a special thanks to Maria Jose Moreno, for the tea breaks and moral support.



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Summaries

English In technical art history, historic recipes are an important documentary source for the study of the

history of materials. Investigating these recipes can provide insight into both artistic and non-artistic

reasons for the choices of ingredients in the past. This thesis aims to investigate the non-artistic

reasons for the use of eggshells in artistic recipes in European documentary sources from the 15th-18th

centuries. Although eggshells have been documented in secondary sources, no one has fully traced

the history of eggshell as a material in art. This thesis further explores how alchemy was a significant

factor in bringing eggshells to the artistic recipe repertoire. In particular, eggshells in recipes are often

burnt to create lime, an ingredient often used by alchemists. Chapter 1 outlines the material history

of the calcium carbonate group of pigments, and shows how eggshells chemically belong in that

category. This helps in understanding how eggshells and chalk are in fact interchangeable as a raw

material. A history of historic recipe sources that reference eggshells is outlined in Chapter 2. Chapter

3 describes how the alchemists burnt eggshells in the process of calcination, by investigating

alchemical illustrations and text sources. In fact, the burning of eggshells to make lime goes back to

Arabic and Greek alchemical sources. Of great interest is the fact that today’s scientists are again

making lime for technical applications from eggshells, as a green technology. This enables us to use

modern scientific research data on eggshell lime to help us understand the alchemist’s reasoning for

making it. Chapter 4 describes the symbolic reasons why eggshell would be an important material to

alchemists, again making use of alchemical illustration. This helps us understand why eggs, and

chicken eggs in particular, were used in these recipes. Also, scientific research today investigates

other birds’ eggs as a lime source, so the alchemical recipe assertions can be tested. Finally, a

comparative review of alchemical and artistic recipes makes up Chapter 5. These comparisons show

that alchemy did have a lasting impact on the choice of eggshell lime in recipes. This concludes the

history of eggshell in artist’s recipes, as it relates to alchemical recipes.



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Nederlands In de technische kunstgeschiedenis zijn historische recepten een belangrijke documentatiebron voor

de studie van de geschiedenis van materialen. Onderzoek naar deze recepten kan inzicht geven in

zowel artistieke als niet-artistieke redenen voor de keuzes van ingrediënten in het verleden. Deze

scriptie onderzoekt de niet-artistieke redenen voor het gebruik van eierschalen in artistieke recepten

in Europese documentatiebronnen uit de 15e-18e eeuw. Hoewel eierschalen in secundaire bronnen

zijn gedocumenteerd, heeft niemand de geschiedenis van de eischaal als materiaal in de kunst

volledig in kaart gebracht. Deze scriptie onderzoekt verder hoe alchemie een belangrijke factor was

bij het incorporeren van eierschalen binnen het artistieke receptenrepertoire. In het bijzonder

worden eierschalen in recepten dikwijls verbrand om kalk te maken, een ingrediënt dat veelvuldig

door alchemisten wordt gebruikt. Hoofdstuk 1 schetst de materiaalgeschiedenis van de

calciumcarbonaatgroep van pigmenten en laat zien hoe eierschalen chemisch in die categorie passen.

Dit helpt om te begrijpen hoe eierschalen en krijt in feite uitwisselbaar zijn als grondstof. Een

geschiedenis van historische receptbronnen die verwijzen naar eierschalen wordt beschreven in

hoofdstuk 2. Hoofdstuk 3 beschrijft hoe de alchemisten eierschalen verbrandden tijdens het

calcineren, door alchemistische illustraties en tekstbronnen te onderzoeken. In feite voert het

verbranden van eierschalen om kalk te maken terug naar Arabische en Griekse alchemistische

bronnen. Van groot belang is het feit dat de hedendaagse wetenschappers opnieuw kalk maken van

eierschalen, als een groene technologie voor technische toepassingen. Dit stelt ons in staat om

moderne wetenschappelijke onderzoeksgegevens over eierschaalkalk te gebruiken om ons de

alchimistische redenering voor het maken ervan inzzichtelijker te maken. Hoofdstuk 4 beschrijft de

symbolische redenen waarom eierschaal een belangrijk materiaal zou zijn voor alchemisten,

wederom gebruik makend van alchemistische illustraties. Dit helpt ons te begrijpen waarom eieren

en in het bijzonder kippeneieren in deze recepten werden gebruikt. Ook onderzoekt de moderne

wetenschap onderzoek de eieren van andere vogels als kalkbron,waardoor de beweringen in de

alchemistische receptuur kunnen worde2n getest. Ten slotte vormt hoofdstuk 5, een vergelijkende

beoordeling van alchemistische en artistieke recepten. Deze vergelijkingen tonen aan dat alchemie

een blijvende invloed heeft gehad op de keuze van eierschaalkalk in recepten. Hiermee wordt de

geschiedenis van eierschaal in kunstenaarsrecepten van de kunstenaar afgesloten, aangezien deze

betrekking heeft op alchemistische recepten.



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Introduction To most of us only a waste product in the kitchen, the eggshell has an interesting place in the history

of art technology and alchemy that can be traced to late antiquity. Eggshells have a wide variety of

uses in the recipe literature. The recipes are diverse and are not only for white painting pigment, but

other artistic applications. These recipes seem to be using eggshell to whiten the product, acting as if

it was chalk. This use can also be found in other recipes where eggshells function with a dye, like

brazilwood, to make a coloured product; in essence, this is a colourant made from dyed eggshell,

known as lake. Also, by the 18th century there are several ‘eggshell white’ pigment recipes where the

eggshell functions simply as a white pigment. However, the most frequent use of eggshells is to make

lime, also described as burnt eggshells or calx. This in turn is used in 15th century recipes for lime blue

(synthetic copper blue), as an improvement to previous lime blue recipes that took months to make.

With this diversity of uses, eggshell appears to have an important role in artistic recipes which needs

to be further explored. The other place in history where eggshells have a use is in alchemical practice.

What is more, is that the use of eggshells in the alchemical corpus is specified to be as calx.

Therefore, it seems that this substance is more than just a substitute for chalk. Ideally any

explanations of these observations should also have scientific validity. To this end, this thesis explores

the connection between these artistic recipes and alchemical references to eggshells.

Rational: While researching the pigments of Japanese art, this topic revealed itself, despite that they

do not at first seem to relate. Sample books are a part of art technological research generally, and the

Rijksmuseum library has a publication with pigment samples in Japanese art included in an appendix.1

This includes samples of coral pink, lead white, and oyster shell white (the latter apparently being the

most popular white in Japan, possibly because Japan is an island). This leaves the reader wondering

whether or not seashell-based whites were popular in European art history. However, my literature

survey showed that references to eggshells, and instructions as to their use appeared far more

frequently than references to sea shells, but chalk remains a significant white material in the art

history of Europe.

Approach: An important question to ask when approaching art historical research from a technical

angle is: How was art made in the past? Answering the question can be helped by the fact that artist’s

recipes have been written for a long time. So, in this thesis, what will be analyzed is recipe text. How

will the text of recipes be analyzed? First, the artistic texts can be compared to other historical

literature, as well as alchemical documents. Next, we will look at historic alchemical illustrations of

two key components of the recipes; the use of chicken eggs and calcination. Finally, modern research

into eggshell calcination will be investigated to better understand the thought process behind the

alchemical and artistic practices of the past. Since modern researchers are already calcining eggshell,

and publishing scientific results about it, performing reconstructions of actual lime recipes for this

thesis seemed redundant.

1 R. Uyemura, “Studies on the Ancient Pigments in Japan”, Eastern Art Annual, No. 3. (1931) 47-50.



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Research Question/Sub-questions: Why would an artist or colourman process eggshells by burning to

make pigments, when there are many other ways to acquire lime?

Since the alchemists treat eggshells in the same way, we can ask a series of sub-questions: Are

alchemists the reason for this ingredient to become part of practice? What reasons did alchemists

have for developing their own eggshell recipe practice? When did eggshells enter recipe literature?

Finally, since alchemy was the beginnings of the modern concept of chemistry, we will investigate the

following: How sound is the science behind the decisions to include this ingredient in recipes?

Place within Technical Art History

To investigate the history of eggshells in art history is a challenging undertaking, as in involves

materials science and alchemical history as well as art technological source research. This is why

technical art history (TAH) is an ideal discipline to tackle this problem as it works at the intersections

of art history and science. Although technical art history can be focused on techniques, it remains a

form of history and as such, a material history can find its place in TAH as a discipline. Therefore,

writing a history is the approach that will be used in this thesis. In the simplest terms, this will put

emphasis on placing the pigment recipes across a broad time scale and in many locations, rather than

on their artistic properties. The artistic properties will not be investigated, as it is too complex to

explore all the nuances of art making within one thesis, while also writing a history. To relate this

history to alchemical history is not out of place in TAH, as there are other examples of alchemical

practice being used to make artist’s materials, particularly pigments, that have already been

addressed in the literature. This thesis therefore, will hopefully compliment other past TAH literature.

In terms of science, TAH frequently uses scientific analysis to further understand the nature of

materials of the past. In the present, research often includes the technique of reconstruction, in

combination with instrumental analysis, to gain a better understanding of artistic practice. Broadly

speaking, this approach necessitates the materials be made from natural raw materials to give them

some historical authenticity. This thesis is different, in that it uses green technology research to offer

a ‘reconstruction’ of eggshell lime. This is not ideal, since it does not directly involve art history, or

alchemical history, but it has its place, which is to offer chemical information about this material. In

summary, this thesis fits into the scope of the interdisciplinary field of technical art history. Its place in

the discipline is to add to our understanding, not only the material of eggshell as an artist’s pigment,

but also its use in relation to alchemical practice.

Background/State of the Art: The egg of the chicken is an object much studied, by many different

disciplines. This fact will aid our technical understanding of this ingredient in recipes. In addition,

biologists and food industrialists are both interested in the biochemical composition of shell and its

formation, as well as its thickness.

In terms of geography, this thesis is focused on Europe, with an emphasis on the northwestern

portion. This would seem to be quite broad for one thesis, but overall is actually quite narrow, within

this topic. For example, there was not enough room here to explore the history of chalk in Arabia, and

its relation to Arabic alchemical practice, nor to consider the ancient Greek alchemical originators,

and their relation to chalk in recipes. As English, German, Dutch, and Italian recipes are referenced,

this is the geographical reference region for geological discussion.



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Throughout the world pigments are a critical component of many artworks, and white, while not a

colour per se, is an important pigment. It is used to create white ground to support and brighten

other colours, and creating highlights and light tones. Aside from its unsuitability to make oil paint,

chalk was occasionally used in painting, despite lead’s dominance in this role. So, an important

question to be addressed is: What is chalk? In chemical terms, it is calcium carbonate (CaCO3),

although this mineral is widely found in nature under other names, such as marble and limestone.

Shells, from marine sources or fowl, are also made of calcium carbonate. The first chapter therefore

will briefly review this material, and in particular, it will discuss the chemical and mineralogical nature

of the material, in a European geographical context. This will help us better understand what the

materials being discussed in recipes actually are. This will be followed by a brief overview of the use

of chalk as a pigment, also in a European context, as well as addressing how eggshell fits into this

calcium carbonate group.

Eggshell is widely acknowledged by historians studying recipes. However, this is usually addressed by

cataloguing old recipes rather than for the creation of new research questions. Also, the internet has

given access to some historic artistic recipes in facsimile of the original form. This issue will be

addressed properly in Chapter 2, with a focus on the book, the Liber Illuministarium.

Calcining is a well-known chemical reaction used to make lime (calcium oxide, CaO) out of calcium

carbonate base materials like chalk. The book Painting Materials: A Short Encyclopedia, offers an

overview of pigments globally. While focusing on oyster shells and coral’s long history in art in Japan

and China, similar applications in European art are not mentioned specifically. The authors, Gettens

and Stout, “suppose” the shells in Japan are burned before use.2 Gettens and Stout also say that

“even eggshells could be calcined to make a kind of lime white.’3 The original sources or why it is

surprising that “even eggshells” were used is missing from this reference. However, there should be

no surprise here as calcined eggshells turn up quite frequently in the recipe literature, and are used to

make pigments other than lime white. Furthermore, alchemists were also frequently referring to the

calcining of eggshells. It therefore follows that further investigation of lime and alchemical calcination

will help us understand why the above authors supposed the shells were burned and would express

surprise that ‘even eggshells’ could be calcined. While it is true that other sources describe the use of

eggshells to make pigments without first turning them into lime, the process of making lime from

eggshells is a repeated feature of the literature. This will be described in detail in this thesis.

Although somewhat forgotten in the Industrial Revolution, in our own ‘post-industrial’ era, there

seems to be a kind of eggshell renaissance occurring that deserves more than a footnote for the

discussion of artist pigments. Eggshells from food processing facilities are a large mass of waste that

in a green economy could offer a value-added use in recycling. It is for this reason that there is a

large amount of research into how calcium oxide (lime) could be produced from waste eggshells. As

an aside, some of these researchers have even taken to waste ostrich eggshell to produce a catalyst

for biodiesel production. Indeed, optimization of waste cooking oil and eggshell (chicken or

otherwise) derived lime production of biodiesel publications are a trending research field. Although

2 R. Gettens and G. Stout, Painting Materials: A Short Encyclopedia, (New York, Dover, 1966),104. 3 Ibid. 104.



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labeled as “green chemistry” the thought of this concoction of kitchen wastes transmuting to the

“black gold” of biodiesel, certainly brings to mind the alchemists of yore.

Although much studied by modern researchers there seems to be a gap in the understanding of the

history of the eggshell as a material generally, and also in artistic production. For example, though

many contemporary scientific articles discuss the potential of eggshell lime production, none

acknowledge the fact the alchemists were working on this, centuries ago. However, the above

information on this topic will enable us to answer the sub-question about the scientific validity of the

alchemical recipes. This in turn will help our understanding as to why this ingredient would still be

used in artistic recipes.



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Chapter 1: Calcium Carbonate Pigment Group: Chalk, Seashell and Eggshell Shell white is part of a larger group of white pigments, the calcium carbonate group. This group which

includes chalk and synthetic precipitated chalk, are widely used in the paint industry today as whiting,

and have been for a long time. Below is a brief account of the chemical compound calcium carbonate

in terms of its chemistry, followed by an investigation of chalk’s place in art history and comparison to

eggshells. This section is necessary to give background to the eggshell recipes, as those recipes are

comparable to similar recipes that use marble dust, chalk, or travertine in place of the eggshells.

Calcium carbonate (CaC03) exists chemically in two major crystal forms; calcite and aragonite. The

aragonite form is much rarer in nature as a natural mineral. There are even rarer crystalline forms of

calcium carbonate represented in the minerals vaterite and ikaite. In fact, at the time of this writing

another form of calcium carbonate was discovered by accident in a laboratory, and announced to the

media.4 However, since this crystal form has not yet been proven to be stable in nature, it will not be

given a common name. Due to the chemical nature of calcium carbonate in minerals, calcite is the

most common form in natural deposits regardless of their source. So, this means chalk, limestone,

marble, travertine and calcitic alabaster, are mostly calcite. Egyptian alabaster is the term used to

describe the calcitic form.5 This background sets the stage for the fact, which will be discussed below,

that eggshells are made of calcite.

However, in other biological sources, aragonite is often present. Therefore, pearls and nacre are

mostly aragonite , although the distribution of this mineral in nature is varied.6 Thus, some seashells

are only aragonite, while others are only calcite.7 Due to the very slightly reduced stability of

aragonite compared to calcite on a geologic time scale, the prehistoric sea life’s aragonite is

converted into calcite in chalk or limestone by nature.8 However, the remains of the sea life that gave

us chalk deposits do leave tiny fossils behind in the chalk, called coccoliths. These are often used by

technical art historians to identify chalk in artworks, as will be discussed below. Now we will turn our

attention to chalk as a specific material and investigate its history.

Chalk History

Chalk is a material known to ancient people. In Latin it is called creta, from which other languages

derived their word for chalk, such as Dutch krijt. However, Latin was unsystematic in its precise

designation, creta meant any kind of white earth; clay or chalk.9 Today we take the context of the

classical writers to understand what they mean; creta from chalk mining regions seems to match the

description of today’s chalk, but many other white minerals could be described in classical sources as

creta.

4 Max Plank Gesellschaft, “More Calcium Carbonate.” 2019. https://www.mpg.de/12771653/chalk-calcium-carbonate-crystal-structure Accessed March 30, 2019. 5 Gettens and Stout, Painting, 118. Gypsum alabaster (calcium sulfate) is also used in art history, but the finer details of this history are out of the scope of this thesis. 6 N.a. “The Mineral Aragonite” 2019. https://www.minerals.net/mineral/aragonite.aspx Accessed May 3, 2019. 7 R. Gettens, E. West-Fitzhugh, and R Feller, “Calcium Carbonate Whites” Studies in Conservation, 19, No.3, (1974), 157-184. 166. 8 Gettens, West-Fitzhugh, and Feller, “Calcium”, 166. 9 The Oxford Latin Dictionary, 1982 ed. s.v. “Creata”

https://www.mpg.de/12771653/chalk-calcium-carbonate-crystal-structure

https://www.mpg.de/12771653/chalk-calcium-carbonate-crystal-structure

https://www.minerals.net/mineral/aragonite.aspx



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The material chalk is too widely used for a complete history of its use in art to be described here. The

temporal nature of our own childhood blackboard drawings attests to the difficulty in fully

understanding man’s creative use of chalk across history. In spite of this, some have said chalk goes

back to “the earliest times.”10 At any rate it has been found, for example, in paint pigments from the

Greek and Roman eras.11 In other words, the exact answers to questions about how mankind learned

to use the colour white on its own, as a support for other layers of colour, or to mix tones with other

colours is lost to history. However, chalk was certainly being used as an artistic material in Europe

during the late Middle Ages as will be discussed further.

In art history, two locations come to mind in the production of chalk for grounds and paint

preparation: Champagne in France, and Bologna in Italy. Also, the proverbial “white cliffs of Dover,”

are strongly associated with chalk. The geography of these locations will be briefly investigated.

Various technical art history literature references describe the grounds of paintings in Northern

Europe generally being made with chalk, particularly in France and the Low countries.12 This art

historical fact matches the geological reality. Most of northwestern Europe is underlain by chalk.

Today, the conservator’s supply website Kremer Pigmente and other sources still sell chalk from

Belgium or the aforementioned Champagne chalk specifically for artistic purposes. These locations,

and the white cliffs of Dover, are from the same deposit as described by modern geologists (Figure 1).

This deposit has given its name to the pigments Troy (Troyes) white, Rouen white and Paris white as

described in the literature.13 These individually named white pigments were thus simply local chalk or

perhaps lead based whites adulterated with the cheaper chalk. These facts demonstrate that,

10 Nicolas Eastaugh, The Pigment Compendium, (Taylor and Francis, London, 2008), 92. 11 Ibid. 12 Gettens and Stout, Painting, 104. 13 R. D. Harley, Artists Pigments c. 1600-1835, (Archetype Publications, London, 1982), 165.



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particularly in the past, locally produced materials were the most widely used by artists at a particular

location.

In Italy, the relationship between artists and chalk is quite different. It is interesting to discover that

Bologna “chalk” contains gypsum. Although sources are slightly conflicted as to whether or not it is

pure gypsum, some gypsum is always present. Even today, the conservator’s supply website Kremer

Pigmente offers the product “Chalk- from Bologna”; which according to the MSDS sheet is a natural

mixture of calcium sulfate (gypsum) and calcium carbonate.14 This is not surprising as gypsum is

mined in the Bologna region, to this very day (Figure 2). Travertine and marble are two calcium

carbonate minerals found in Italy, and occur in Italian artistic recipes, in powdered form. Then there is

gypsum, or gesso in Italian, which has its own history of use in art. The lack of references to eggshells

in Italian recipes will discussed later.

Chalk is usually found in the ground layer of northern European polychrome sculpture, and this also

goes back in time. Studies of Norwegian polychromy identified chalk in the ground layer, where chalk

is not native. Using microscopic fossil studies, it was found that between 1100-1250 chalk for

polychrome ground was imported from England.15 Later, chalk came from France. This means that, by

1100 chalk was being shipped as a commodity, and used for artistic purposes. Another artistic use of

chalk, which goes back to the Middle Ages, was to precipitate lake dyes made from organic colourants

like brazilwood to be used as pigments. In many recipes, this is accomplished by using powdered

chalk. In England, however, dye solution was poured into a hollow made in a solid block of chalk, and

14 Chalk from Bologna, Italy, MSDS No. 58100 (Online); Kremer Pigmente, Aichstetten, Apr. 3, 2003. https://shop.kremerpigments.com/media/pdf/58100-58150MSDS.pdf Accessed May 2, 2019. 15 Lucretia Kargère and Adriana Rizzo “Twelfth-Century French Polychrome Sculpture in The Metropolitan Museum of Art: Materials and Techniques”. Metropolitan Museum Studies in Art Science and Technology, 1 2010, 39-72, 43-44.

https://shop.kremerpigments.com/media/pdf/58100-58150MSDS.pdf



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the lake pigment was collected out of the hollow.16 It is no coincidence that this extravagant

technique is from a nation known for white chalk cliffs that easily provide these blocks.

The interpretation of this information is complex. On the one hand, there is a clear geographical

connection to the minerology of regions and local art recipes. The Italians, being isolated from the

north by the Alps, used local material from gypsum deposits. However, there is evidence that chalk

for artistic purposes was shipped even during the Middle ages. It seems that skill and human

movement would also be a factor here. Certainly, in the Middle ages the Anglo-Saxon cultural impact

would be greater in Norway than Italian influences. So, chalk was moved to where it was needed; the

locations where craftsmen were taught to use it. In addition, it was interesting to consider that it is

not always clear what chalk actually means in historic sources, and that problem continues into our

own time with Bologna chalk. This is important for the critical reading of recipes.

Calcium carbonate in eggshells

An egg is a complex biological system, and as such has been much studied in science. One study from

1996 presents a good summary diagram of what an eggshell looks like in cross section (Figure 3).

Although presenting all of the complexities the diagram shows the shell is composed of four main

layers. The innermost layer, a membrane or skin gives the system a separating barrier between the

egg white and shell. It is composed of collagen and other proteins. The majority of the shell adjacent

to the membrane is calcium carbonate crystals in the calcite form. This is combined with palisade

vessels within this mass of crystals. Between this layer of calcite and the top membrane researchers

16 Daniel V. Thompson, The Materials and Techniques of Medieval Painting, (New York, Dover, 1956), 140.



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have identified a thin layer of hydroxyapatite.17 This is a calcium-phosphorus compound with the

formula Ca5(PO4)3(OH), and the main component of human bone.18 However, the middle layer is so

much thicker than the rest of the shell, that the eggshell as a whole is mostly calcium carbonate, with

only a small protein component.

In conclusion, calcium carbonate can come from many sources and is clearly influenced by local

geography/geology. The placement of eggshells in the calcium carbonate group of pigments makes

sense, because calcium carbonate in pigments from chalk usually comes in the mineral form of

calcite. As a final note, one reference was found to research on Roman frescos where aragonite was

identified spectroscopically as the white material used specifically to mix colours in the painting

process. The authors do not acknowledge the possibility of shell white, but instead suggest it is a

natural creta, as described above, that happened to consist of aragonite.19 Similarly, seashells more

often contain aragonite. As it turns out, the eggshell is a relatively pure source of calcium carbonate

as calcite.

17 J. E. Dennis, Arthur Heuer, “Microstructure of matrix and mineral components of eggshells from white Leghorn chickens (gallus gallus)” Journal of Morphology 228 (1996), 287-306. 18 “Hydroxylapatite” Mindat, 2019, Hudson Institute of Minerology https://www.mindat.org/min-1992.html Accessed May 25, 2019. 19Gian Antonio Mazzochin, Emilio Francesco Orsega, et al. “Aragonite In Roman Wall Paintings of the 8th Regio, Aemilia, and 10th Regio, Venetia et Histria” Annali di Chimica, 96, 2006, 377-87, 386.

https://www.mindat.org/min-1992.html



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Chapter 2: Eggshell Pigments: An Overview Although Gettens and Stout described a kind of lime white made from eggshells, the usage of this

ingredient in recipes is more diverse than as a white pigment. Several sources describe a very specific

use for eggshell in art technology, which is the production of lime blue. Lime blue is a pigment used in

wall painting whose exact chemical composition is still questionable, despite the advances in chemical

research. Its class is in the synthetic copper blues, meant as alternatives to azurite. While many

different approaches to synthesizing blue from copper (or brass) in the late Medieval period have

been discussed, the one that matters to us is blue made from verdigris, sal ammoniac and lime. This

has been well studied in a paper in the journal Studies in Conservation, where long list of 15th century

sources for recipes based around this formula are discussed.20

The recipe writers working north of the Alps specify eggshell lime in recipes. Note, in Chapter 4 we

will address the fact that 8th century Arabic alchemists used the same ingredient list in non-artistic

recipes. However, it is also known that verdigris comes to Europe from the Arabs anyway.21 One of

the recipes from this list is taken from the Amberger Malerbuch, and apparently came from a

Viennese source. It will be discussed in Chapter 4/Appendix I. The Italians also made this lazur

pigment, but in a different way. The lime used was specified to be made from marble or travertine in

two recipes, both from the Bolognese manuscript.22 This raises the question: If the Italians knew

about this formulation for lazur, why would they choose other lime sources over eggshells? Alchemy

was certainly practiced in Italy at the start of the early modern period. However, it seems the Arab

presence in Spain meant their alchemical manuscripts moved into central Europe from there more

readily than into Italy.

One must mention the outlier here, a Dutch recipe from Ms Sloane 345 B, which says to use lime

made from either eggshells or marble.23 There must be a combination of German and Italian

influences here. It thus is suggesting that the source of the lime in fact doesn’t matter. Why the

Germans and Italian came to specify different sources of lime remains unknown. Later in time, other

recipes can be found in the literature, besides these lime blue recipes. The book Artist Pigments c.

1600-1835 lists English language printed books that contain eggshell pigment recipes. Two of those

recipes will be discussed further in Chapter 4. However, these recipes are more modern, from the 18th

century, and are for eggshell white specifically. Again, this is not the lime white described by Gettens

and Stout. In summary, it seems that Gettens and Stout had a poor understanding of the role eggshell

calcination played in artistic recipes. Instead of only acting as lime white, as they describe, it had a

role in being prepared specifically for the production of another pigment, lime blue.

Significantly, of the nine Germanic language references to eggshell lime described in the Kreigel and

Polborn tabulation of lazur recipes, five are from the same source, officially titled: Liber

20 Christoph Krekel and Kurt Polborn, “Lime Blue- A Medieval Pigment for Wall Painting?”, Studies in Conservation 48 No. 3 (2003), 171-182. 175. 21 Spansgrun (Spanish Green) in German, and verdigris (Green of Greece) from French, still indicate the Arabic world’s influence on the introduction of this copper salt to Europe. 22 Krekel and Polborn, “Lime Blue” 175. 23 ibid



15

Illuministarum pro fundamentis auri et coloribus ac consimilibus collectus ex divirsis. This book will

now be discussed in more detail.

Liber Illuministarum: The Tegernsee Manuscript

An important source to consider for eggshell-based pigment recipes is what is called “the Tegernsee

Manuscript”, or Liber Illuministarum, the ‘book for book illuminators.’ This collection contains over

600 art technology recipes written in German and Latin.24 One recipe from this book will be discussed

in depth in Chapter 4; the other recipes will only briefly be reviewed here. The Tegernsee Manuscript

comes to us from the Benedictine monastery in Tegernsee in Bavaria. Although founded in the

middle of the 8th century, the monastery was sacked by Ludwig of Bavaria in 1206, then damaged by

fire in 1206 and 1211.25 This suggests that the recipe sources are later than this, and it appears likely

that much information was lost. Liber Illuministarum is dated to the second half of the 15th century

and has many recipes that are unique to it.26

Conveniently catalogued in the 2005 print edition, the index lists several recipes that use eggshell,

including instructions to make eggshell lime. This substance, eggshell lime, itself in indexed separately

(eiernschalenkalk), and is put to use in many of its own recipes, particularly to make the

aforementioned lazur, of which quite a few versions exist in this book. The reason that more

references to lazur appear in this book than Krekel and Polborn describe in their 2003 lime blue

paper, is that many of the instructions in the hundreds of pages of manuscript in this book are

repetitions, or cross references within the manuscript. As described in the title, (‘A Medieval Pigment

for Wall Painting?’), Krekel and Polborn’s paper explores the possibility of lazur being used as a wall

painting pigment, mainly due to the expense of natural ultramarine. Evidently, lazur was also

important to the book illuminators, as is expected from the book’s title. On top of this, many a recipe

using or making glair, (egg white as a painting medium/varnish/adhesive) are in this book. Glair is

known to be important for traditional book makers so this further validates the book being used as

instructions for book illuminators. Here it is worth mentioning that the use of glair/egg white as well

as yolk (i.e. tempera) in recipes throughout the Tegernsee Manuscript suggest there was an available

source of eggshells to the user.

Another recipe, somewhat unexpected uses eggshell lime (Original German aẏr kalch) with alum and

brazilwood in a pigment lake.27 It is unexpected since, as described above, chalk (not quicklime) is

traditionally used to make lakes. However, we will see a secondary source below that suggests blue

lake was made with eggshell lime and woad in 15th century England. In addition, there is also a recipe

for cleaning pearls that uses quicklime (calcem viuam), egg white and calce ovorum (eggshell lime).28

Although it may not count as an artistic recipe per se, it does show that eggshell lime was seen at that

time as somehow being different than ordinary quicklime.

24 Joyce Hill Stoner, Rebecca Rushfield, Conservation of Easel Paintings, (Routledge, Oxford, 2012) 21. 25“Tegernsee, Benediktinerabtei St. Quirinus”, MRFH, 2012, https://www.mrfh.de/2590 (Accessed May 29, 2019) 26 Stoner, Rushfield, Conservation, 21. 27 Bartl, Der “Liber”, 374-5. 28 Anna Bartl, Der “Liber Illuministarum” aus Kloster Tegernsee, (Stuttgart, Franz Steiner, 2005). 123-4.

https://www.mrfh.de/2590



16

So, in summary, eggshell was an often-used ingredient in 15th century recipe writing in the Germanic

cultural area. The most important point to take away from this is the frequency at which eggshell was

processed to lime. The lime becomes arguably more important than the raw eggshells itself. First, we

have seen that eggshell lime was put to other uses besides lazur production. Also, a recipe is provided

for making eggshell lime itself. This is important since it suggest that artists were expected to make

the lime themselves.

The conclusion here is that is a lot more to eggshell calcination in recipes than the ‘kind of lime white’

referenced by Gettens and Stout. The reasons for this variety of uses will be discussed in the following

chapters, beginning with an investigation of calcination in an alchemical context.



17

Chapter 3: Alchemical Calcination

Written Sources Now we will focus the research into eggshell lime production specifically. This comes about from a

comment published in the aforementioned journal article describing the synthesis of lime blue

pigment:

“…Dutch or German sources describe the use of lime produced from eggshells (in their recipes). This

last material indicates some connection between these recipes and alchemical laboratories, where

lime from eggshells was extensively used.”29

Furthermore, the book The Pigment Compendium describes eggshells being sold as a pigment at a

Munich pharmacy in the 15th and 16th centuries.30 The product in the listing is “Calx de tistis ovorum”-

in English, calx of shells of eggs. Calx, or lime, is what is being sold here, not normal eggshells. It is

worth noting that The Pigment Compendium does not note this distinction. In the lime blue recipe

literature eiernschalenkalk or gebrandt eierenschalen are both referenced, and assumed to be the

same thing. The choice of this Germanic salesman to use the Latin name for this product may show a

connection to the manuscripts of the 15th century compiled in the aforementioned Liber

Illuministarum, which mostly used Latin in the recipe instructions despite being compiled in Germany.

The question as to whether eiernschalenkalk, gebrandt eierenschalen, eggshell lime and burnt

eggshells, in English and calx in Latin are always describing the same thing, seems clearly in the

affirmative when one reads sets of similar recipe instructions, which use the various terms

interchangeably. A more pertinent question might be, why would some writers choose

gebrandt/burnt to describe the ingredient, when it is actually something quite different? This will be

discussed in more detail later in this chapter.

The book The Materials and Techniques of Medieval Painting by Daniel Thompson is a good

secondary source about pigments. His references to eggshell lime include recipes where calcined

marble dust or lime made from eggshells is used to make a blue pigment from waste woad dyeing

solution. Unfortunately, this reference is only “a 15th century manuscript in Cambridge” and cannot

be traced further.31 The other reference in Thompson concerns the author Cennino Cennini’s

description of calcining bones, where they are put “into the fire… until they are whiter than ashes.”32

Thompson says verdigris and orpiment were sometimes whitened with “eggshells, calcined in the

same way as bones.”33 It is again disappointing to not be able to get to primary sources from this.

What can be said is that there are two different uses for eggshell lime are described here.

In conclusion, lime produced from eggshells evidently exists and was described in artistic recipes. As

discussed in Chapter 2, most of the primary sources available today are from 15th century Germany,

an historical period when lime was produced by the process of calcination at high temperatures. This

29 Krekel and Polborn, “Lime Blue” 175. 30 Eastaugh, Compendium, 153. 31 Thompson, The Materials, 140. 32 Thompson, The Materials, 95. 33 Ibid. 96.



18

process can be applied to almost any material, so the role of this process in alchemy will first be

introduced, before a discussion of the relation between alchemists and eggs.

Use of Calcination by the Alchemists: Lime and Language

In modern thinking, calcination is the decomposition of calcium carbonate into carbon dioxide and

calcium oxide, or lime, by heat. The process of calcination, from which the word calcium is derived, is

ancient, as the Romans made use of lime in mortar. Calcination is an important process which has an

impact on the history of pigments. Although mostly known as having a critical role in the process of

buon fresco, the process to produce lime is used to produce a product that was an ingredient in

pigment recipes, and was also used as white pigment in secco painting. So, the history of this process,

in an alchemical context, will now be examined as it relates to the use of eggshells in pigment

manufacture.

A thought here can be given to language heritage; in English technical usage, calcium oxide, CaO, is

quicklime and calcium hydroxide, Ca(OH)2 is slaked lime. Where do these terms come from? Lime is

an Old English word of Germanic origin and so relates to the Dutch lijm, and German leim.34

Linguistically they may relate to the practice of adding lime to farming soil to improve its fertility.35

Loam (a kind of light soil for farming) comes from this root, which again relates to the Dutch leem and

the German lehm.36 ‘Quick’ as a preface comes from the Old English cwic, cwicu ‘alive’, which is

distantly related to the modern English word quick.37 This means the calcium oxide produced by

calcination is ‘living lime’. Meanwhile, the verb to slake in English means to diminish or reduce (one’s

efforts, or thirst), and has been in use since around 1000 AD.38

It is not a stretch of the imagination to put yourself in the minds of the pre-Enlightenment thinkers.

Calcium oxide is quite caustic; it is “alive”, and as a “living” being it needs its thirst “slaked” with

water to ‘’calm it down” and make it more useful in construction or as a surface coating. When

quicklime is slaked, it swells up in volume and makes the water it is placed in boil. Also, it is worth

remembering that the alchemists left this form of language on another English word; quicksilver, or

mercury. The name naturally is related to mercury’s nature as the only metal that is liquid at room

temperature. The Dutch and Germans retained the common Germanic stem -cwic for naming this

metal, connecting it to alchemical naming. This ‘living’ silver in the English language also maintained a

12th century alchemical title of planetary association with metals, Mercury for the first planet in the

34 "lime, n.1". OED Online. March 2019. Oxford University Press. https://www-oed-com.proxy.uba.uva.nl:2443/view/Entry/108432?rskey=QVXTJT&result=1&isAdvanced=false (accessed May 25, 2019). 35 "loam, n.". OED Online. March 2019. Oxford University Press. https://www-oed-com.proxy.uba.uva.nl:2443/view/Entry/109439 (accessed May 25, 2019). 36 Ibid 37 "quick, adj., n.1, and adv.". OED Online. March 2019. Oxford University Press. https://www-oed-com.proxy.uba.uva.nl:2443/view/Entry/156418?rskey=6VRLvj&result=2&isAdvanced=false (accessed May 25, 2019). 38 "slake, v.1". OED Online. March 2019. Oxford University Press. https://www-oed-com.proxy.uba.uva.nl:2443/view/Entry/181279?rskey=KQLkzj&result=7 (accessed May 25, 2019).



19

solar system.39 This is opposed to the Classical heritage of hydrargyrum (‘water-silver’) as the Latin

word for mercury, which is maintained as the symbol Hg on today’s periodic table.

Now we shall give a closer look at the Latin word calx. Calx is defined in the Oxford Latin Dictionary as

limestone or lime. Another Latin dictionary gives the similar definition only with the added

clarification that the lime could be slaked or unslaked.40 The Oxford Latin Dictionary further focuses

this word definition as pointing out that calx viva “living lime’’ is quicklime: the alchemical language

heritage in English in fact draws on the classical tradition. There seems to be some confusion over

what exactly calx means, as limestone and lime are two entirely different materials. However, for our

purposes, ‘calx of eggshells’ could logically only be lime, or calcium oxide.

The book Cyclopædia, or, An universal dictionary of arts and sciences, by Ephraim Chambers, (1728) is

an interesting source in its own right. Apparently one of the first English language encyclopedias, this

offers many definitions couched often in pre-Scientific Revolution- language that can help us peer

into how people thought at the turn of the 18th century or earlier. Calcination and related

terminology are given an extensive article in this encyclopedia. Although there is no specific mention

of eggshell lime some things described are relevant to the present discussion. “Potential calcination”,

by the action of corrosives that contain “potential fire” like sal ammoniac is described as a possible

process, which chemistry now knows is in no way related to the action of heat in a kiln.41 Also the

process of calcination is said to occur when the “… particles of fire likewise do insinuate themselves…

throughout its whole substance, so that the fluidity that was first caused by the fire can no longer

subsist.”42 Again, this is not a modern scientific view of a reaction. The energy heating a substance to

drive a chemical reaction is much more complex (and less humanized) than insinuation by particles of

fire to create “a third body” after the heating process.43 The main point to take away is that even in

the early 18th century, the understanding of calcination was still quite far from the reality of modern

laboratory processes. It is therefore quite probable it would have also been seen that way by artist’s

colour makers of earlier centuries, and naturally by extension, the alchemists themselves.

In terms of putting this into the context of the research question, about processing eggshells, let us

first consider that Cennini’s description of calcination is simply putting something into the fire.

Furthermore, as mentioned above; why use the word gebrandt/burnt to describe this product in

recipes? In his book The Tacit Dimension, British philosopher Michael Polanyi writes “we can know

more than we can tell.”44 This concept became known in academia as “tacit knowledge”, i.e. writers

presuming (or assuming) prior knowledge of the topic from the reader in their document. The

confusion between properly calcined eggshells and burnt eggshells can be explained by considering

the tacit knowledge factor. In other words, there is a reason to believe that artist recipe writers

presumed the reader, for example, would already know not to simply hold a piece of eggshell in a

candle flame when indicating gebrandt eierenschalen as a recipe ingredient. There seems to be no

39 "mercury, n.". OED Online. March 2019. Oxford University Press. https://www-oed-com.proxy.uba.uva.nl:2443/view/Entry/116711?rskey=dpX0B0&result=1 (accessed May 25, 2019). 40 Freund’s Latin Dictionary, 1951 ed. s.v. “Calx” 41 Ephraim Chambers, Cyclopædia, or, An universal dictionary of arts and sciences, (London, 1728), 141. 42 Chambers, Cyclopædia, 141. 43 Ibid. 44M. Polanyi, The Tacit Dimension. (New York: Doubleday, 1966), 4.



20

sense of deliberate obfuscation by the writers here; after all the alchemical recipe instructions to

make lime are uncharacteristically straightforward, since we know what they are today. So, there is

no reasonable argument that artists would be more esoteric in their recipe writing.

Now we will consider another source of information about alchemical calcination to further

understand this process: alchemical illustrations.

Illustrations Calcination is one of the key alchemical processes, and was illustrated in printed books both

mystically (Figure 4) and in not so obscure ways (Figure 5). Furthermore, investigation of illustrations

of workshop techniques in printed books or manuscripts is an important art technological source for

today’s researchers, as in earlier times there were no cameras to document workshop practice.

However, as will be shown, the use of illustrations may be limited in reconstructing a technology, as

artistic license will affect what is depicted.

If any doubt exists about interpretation of the image in Figure 5 for the process of calcination,

“calcinatio” inscribed on the table in this image puts it to rest. Interpretation of the characters in

Figure 5, such as the apparent sun king and queen or the lion and snake, is out of the scope of this

thesis. What this image does offer, however, is a view of a kiln (for calcining materials) in operation.

At the base is a door to ventilate and tend to the furnace. On the second tier is a smaller door

apparently for the substances to be added to the kiln, using the tongs held by the alchemist. It seems

likely that this is an alchemical kiln specifically for calcination or metalworking, as the small door is

inadequate for pottery or bricks to be placed in the kiln in large batches.

However, we will now see how there can be problems with this simplistic interpretation. The image in

Figure 5 is part of a series and reproduced from J. D Mylius’ 1622 publication Pilosophia Reformata in



21

a modern book. That book’s author, Stanislas Klossowski de Rola, without reference, says they

“constitute one of the finest collections of alchemical engravings in existence.”45 He goes on to

describe how “many of them have been used by other alchemists to illustrate their own texts.”46

However, the story does not start in 1622. In 1618, Michael Maier published the Tripus Areus, an

illustrated book on alchemy. This book is in fact a compilation that includes the Twelve Keys of Basil

Valentine, an earlier alchemical text of notoriety, which may be the first published description of

antimony.47 However, to this thesis the part that matters are the depictions in the illustrations. The

text describing twelve keys are twelve esoteric descriptions of laboratory practice. Each of the twelve

keys was illustrated with its own engraving. The engraving of the twelfth key bears a striking

resemblance to Figure 5 (Figure 6).48

All of the symbols from that illustration, like the sun and moon and lion and snake are present here,

but the furnace is quite different. Instead of the proper furnace of stone with two doors from Figure

2, this furnace appears as a metal or ceramic barrel with a small round door in the bottom, and

smoke and flames escaping out the top. Another edition of Tripus Areus published in Germany in

1677 contains yet another set of illustrations (Figure 7).

This 1677 version also has the furnace as a barrel. Every other detail, including the two flowers and

the lion devouring the snake are nearly identical across the three prints. This demonstrates that there

were different ways to depict a furnace, in illustrating alchemical workshops, even though devouring

animals and other symbols were codified in that time. Upon reflection it would seem that the

rectangular two-tier kiln of the Mylius illustration, is the more realistic of the two possibilities.

45 Stanislas Klossowski de Rola, Alchemy (New York, Avon Books, 1973) 98. 46 Ibid 47 C. S. Pierce, “Note on the Age of Basil Valentine” Science, 8, No. 189 (1898), 169-176. 48 This is the 1678 edition. It is clear that this engraving first appeared in the 1618 edition, but those editions are in an unacceptable quality of digitization, or not copyright cleared for reproduction in this thesis.



22

Indeed, that two-tier kiln illustration is in fact in the general form of an athanor, the name for an

alchemical furnace (Figure 8). The woodcut in Figure 8 comes from the book Alchemiae Gebri (1545).

This kiln is round, and made of bricks with the doors on each tier as before. It is interesting that it

shows some kind of shelf with round notches in it at the base of the second tier.

These are likely to hold crucibles, but may also be to collect ashes. The idea of the ash collection

comes from the inexplicable fact the fire is clearly on the top, not at the base like a traditional

fireplace. Are the two levels of doors present only for ventilation, and not to tend the fire? It is worth

remembering that in this case the furnace looks like it is serving to heat substances within the bottle

shaped container at the center, in a water bath. The illustrations are similar enough that it is quite

possible that Mylius’ illustrator was simply copying the earlier furnace illustration, combining it with

the symbolism from the Tripus Areus prints rather than observing a real furnace.

Stefan Michelspacher's Cabala: Spiegel der Kunst und Natur, in Alchymia (1615) is another illustrated

alchemical book to discuss. This book has been written about from the viewpoint of addressing the

illustrations for religious symbolism. Scholars argue that either these illustrations “loosely relate to

depicting alchemical practice” or that they are a practical guide to alchemy.49 However, there is no

doubt that they are a depiction of early 17th century alchemy in some regard. Now let us look at the

engraving. The first engraving in this book is described as illustrating calcination and entitled, in

translation, “the mirror of art and nature” (Figure 9). This engraving is divided into three panels, of

which only the bottom depicts laboratory work.

49 Alinda van Ackooy. “Through the Alchemical Looking Glass: An Interpretation of Stephan Michelspacher’s Cabala: Spiegel der Kunst und Natur, in Alchymia concerning the Tincture of the Alchemists” Master’s Thesis, University of Amsterdam, 2016. 8.



23

It has been described that this image is describing how both a wet and dry path towards calcination

can be taken, the wet path clearly representing what we call distillation. However, for the remainder

of the discussion, we will examine only details of the dry path calcination detail as shown in the

bottom panel (Figure 10).

This image shows an alchemist working at a furnace. In his hand he holds a device called a diopter.50

This enables him to look inside the furnace without damaging his eyes, similar to modern welding

safety devices. On the ground around him are various crucibles, tongs and fire caring tools. In the

center is a quenching bucket of some kind, boiling away from the red-hot crucible placed in it. Beside

the furnace are what would apparently be the most important tools to tend the furnace, a poker,

tongs, and a bellows. The bellows are important to keep the furnace at the hottest possible

temperature. On the wall directly behind the furnace are what appear to be small shovels. Below

them is an indeterminate pile of material that could be ashes or fuel.

The possibility of the fuel being charcoal or coal is increased by the fact there is no stack of logs or

chopped wood anywhere in this laboratory. By the distillation area on the ground are two baskets

and tools including shovels (Figure 11). This larger basket being more likely the fuel storage, with the

ashes swept away in the pile behind the furnace. The suggestion that this object is the coal basket is

also found in the literature interpretation of this print.51 Either way this is an important observation

50 van Ackooy, “Through the Alchemical”, 36. 51 Ibid, 35.



24

since it indicates a possibility that firewood was not burnt in these furnaces. Burning better fuels than

wood in these furnaces would have increased the temperature.

The furnace itself is very typical, if one interprets the image carefully. On the floor is a stone plinth,

which has a sturdy table propped up on it. This should not be interpreted as a separate hearth. When

one compares the actual two-tiered furnace set-up on the table to Figure 5, there is a resemblance,

although the door on the upper tier is in a different position (Figure 12). Again, a pile of hot embers

seems to rest on the very top of the furnace. However, these may be somewhat artistic licenses since

a plume of smoke, sparks and flames flowing from a furnace is difficult to illustrate in black and white

at this fine detail. In summary the Spiegel der Kunst und Natur, in Alchymia is an excellent source to

investigate calcination technology in the early modern era.

To place these illustrations within the broader research question, as described above; there seems to

be some confusion about applying this technique to ‘burning eggshells’ in recipes. As calcination of

calcium carbonate is unsuccessful below 900 °C, it is no wonder that the alchemists worked on kiln

technology, accessories such as the diopter and bellows, and use of different fuels in order to

facilitate this reaction. If more research is to be done on alchemical furnaces in the production of

artist’s pigments, reconstructions of those processes would be valuable. In this case, it is important to

look closely at what is depicted in illustrations so we can build an historically accurate furnace to work

with. The furnaces depicted in the illustrations are specific enough that not everything depicted was

fantasy.



25

However, a question that remains from observing these illustrations is: when book illuminators

wanted to make lime blue from a recipe, did those monasteries have access to calcination kilns to

prepare burnt eggshells at 900 °C? Or, as described in the Pigment Compendium reference was ‘calx

de testis ovorum’ sold at pharmacies ready-made? The alchemical instructions are usually clear as to

what is being done, (calcination), but the artistic recipes not as much, simply calling it burning. In

conclusion, when carefully interpreted, these images above describe what was necessary in

alchemical laboratories in the early modern period to process eggshells for artist’s recipes. This helps

us better understand the way eggshells were handled from kitchen to pigment grinding stone.

Modern Scientific View From what has been discussed so far in this chapter, it is clear that the alchemists had highly

developed calcination technology as a process, although they did not understand the chemistry

behind it, as we do today. What follows is a critical assessment of the role calcination played in the

alchemical and thus artistic recipe, from the viewpoint of scientific history.

In alchemical history in Europe, Jabir Ibn Hayyan (c. 721-815) is a crucial early figure, and considered a

founding father of chemistry, who is believed to be from today’s northeast Iran.52 He is part of the

larger Arabic alchemical world, which while not inventing alchemy itself, allowed Greek alchemy to be

brought to Europe during the Middle Ages. It is worth remembering that his biographical details were

“convoluted” as early as the 10th century.53 In the West, he has become known as Jabir, or Gerber

when Latinized. The true meaning of his corpus, and how it came to the West, is still debated by

historians. In one particular recipe, Jabir instructs the reader to take the “best quality of white calx of

eggshell” as a recipe ingredient. 54 This bears closer examination. Would not eggshell lime always be

white?

Certainly, it is prescient, as referenced above, that Cennino Cennini desired calcined bone to be

whiter than ashes. However, what can be said specifically about eggshell lime? The alchemists of

Europe were aware of this property. Paracelsus (1493-1541) discusses in his book, Aurora

Thesaurusque Philosophorum, hens-eggs and eggshell lime as ingredients. Henceforth, this book will

be referred to as simply Paracelsus’ Aurora. The version of that text used here is the publication

which was “faithfully Englished (sic)” in 1659 by J. Oxon. In it we read a description of eggshell calx

“as white as snow” in a recipe for the fixation (transmutation) of mercury. 55 In conclusion the white

nature of an eggshell lime as an indicator of quality is well documented in the alchemical literature. It

could be inferred that this purity concept was known as early as the 8th century.

The white qualification of eggshell lime described by Jabir, continues to be a noted property in

eggshell lime production history. The instructions given in the book The Art of Chymistry (sic) (1668)

by P. Thaibault, are also worth mentioning. The details of the process and ingredients of this recipe

will be discussed elsewhere in this thesis. For the present, what matters is the descriptor that the calx

52 Amr, Samir S. and Tbakhi, Abdelghani. “Jabir ibn Hayyan” Annals of Saudi Medicine, 27 (1), (2007) 52-3. 53 Thomas F. Glick, Steven John Livesey, Faith Wallis, Medieval Science, Technology, and Medicine: An Encyclopedia, (London, Taylor and Francis) 2005, 279. 54 A. Y. Al-Hassan Science and Technology in Islam: Technology and applied sciences (New York, UNESCO, 2001) 58-59 55 Paracelsus, Paracelsus, his Aurora and Treasure of the Philosophers, (London,1659), 20.



26

of eggshells produced is as “white as snow.”56 So, more than a hundred years after the death of

Paracelsus, this is still an important aspect to lime production from eggshells. Naturally, this may

simply be an uncredited quotation of Paracelsus’ writing by Thaibault.

This visual property of the lime has been recorded in other sources, from our own time. An

interesting connection to modern research can be found in a journal article describing eggshell lime’s

use in making ‘green’ mortars for historic building restoration.57 This article regrettably makes no

reference to the history of eggshell lime in cultural heritage, or even lime history in general. The

purpose of this reference is to show ESL (eggshell lime) alongside CL (commercial lime, from

limestone) (Figure 12). For comparative purposes to other research, the illustrated eggshell lime was

calcined at 1000 °C. Another illustration in th3 article shows the author’s steps to produce slaked lime

from the raw shell (Figure 13).

Here is a good place to address the main research question of this thesis; why not use chalk instead of

eggshell to make lime? As was shown in Chapter 1, calcium carbonate comes from many different

sources such as travertine, chalk, and limestone. Lime for mortar has been made since antiquity from

many different sources of calcium carbonate. Seashells have been used to this end, and are just more

practical to use for industrial scale production verses chicken eggshells. Also, as lime is a mass-

produced product for construction projects the chances that impurities would affect the final product

is high. There is one reference, again from our own time that tentatively addresses this. Lime mortar

prepared from Lincolnshire chalk is sold online for building restoration. This is indeed part of the

same chalk deposit described in Figure 1. The product is described as cream coloured.58 So perhaps

even natural chalk does not produce a lime as ‘snow white’ as eggshells do, because of mineral

56 P. Thaibault, The Art of Chymistry: As it is Now Practiced, (London, John Starkey, 1668). 208 57 Kevin Beck et. al. “On the use of eggshell lime and tuffeau powder to formulate an appropriate mortar for restoration purposes” Geological Society London, Special Publication. 331, (2010) 137-145. 58 Mortar Grade Chalk Lime Putty; Rose of Jericho, n.d. https://www.roseofjericho.co.uk/product/mortar-grade-

chalk-lime-putty Accessed June 3, 2019.

https://www.roseofjericho.co.uk/product/mortar-grade-chalk-lime-putty

https://www.roseofjericho.co.uk/product/mortar-grade-chalk-lime-putty



27

impurities. Another important point for research and reconstruction is in Figure 13; apparently it does

not matter if the shells used in calcination are from brown eggs. This means that any hen’s eggshells

could be used to make lime that was very pure. Again, it seems that tacit knowledge is something in

the recipes where no one acknowledges the exact kind of (chicken) eggshells that are burnt.

However, once you have learned more about the process, you understand that it actually doesn’t

matter.

In the spirit of the alchemists described above, today’s entrepreneurs are seeking high quality lime for

industrial applications. To that end, many peer reviewed articles about the process of calcining

eggshell appear in chemical engineering or agricultural journals. So it was valuable to consult those

sources to get a modern perspective on this alchemical ingredient. It is worthwhile pointing out, as

mentioned further in Chapter 4, that nearly all of the modern scientific studies of eggshell lime were

conducted at southeast Asian and Indian universities.59 Therefore, there is potential for a difference

between the exact physical properties of those eggs and historic eggs in Europe, where the artistic

recipe usage flourished. Scientific proof that these differences could affect the lime prepared from it,

is addressed in Chapter 4. One of these Asian research articles describes the colour properties of

restaurant waste eggshells (in Indonesia) as they are heated in a modern furnace with measured

temperature gradients.60 Their results are illustrated below (Figure 14). Only at 900 °C and above is

the product made stark white again, which is shown in the analysis to be almost pure calcium oxide.

In other words, by examining the modern replication of the original eggshell lime, it is suggested that

a bright white appearance is a sign that high temperature calcination results in high chemical purity.

59 This is likely due to the fact that hot, humid climates would naturally invest more in the hygienic recycling of food waste. 60 Risfidian Mohadi et al. “Preparation Calcium Oxide (CaO) from Eggshells” Sriwijaya Journal of the Environment. 1, 2, (2106): 32-35 33.



28

In summary, even within modern technology, calcination of eggshells works as intended. This is

evidenced in particular by chemical analysis which shows remarkable purity to the product. As has

been the case for over a millennium, the white nature of the product is noted experimentally. This

product is not only a curiosity today, but has been used in serious chemical experiments such as its

use as an alkali in the Knoevenagel condensation, to produce unsaturated ketones.61 We must

remember that today’s eggs are not the same in every corner of the world, and yet research from

France and Indonesia created similar white lime. Although time would no doubt also affect the quality

of eggs, through the adaptation of new chicken breeds, the documented research also has the same

variability. An 8th century Arab writer and 16th century Swiss writer have both commented on the

white quality of this lime. So, it seems to be quite intrinsic to this product, regardless of the time and

place. In summary, it is proposed that the white qualification of lime made from eggshell compared to

other limes was an important reason for its choice in recipes.

This scientific evidence helps answer the main research question of why eggshell would be chosen to

make lime for artistic recipes above chalk. This research, however, is far from typical technical art

historical research. It is a case of scientific research being used for a greater understanding of a

historic material and alchemical process. It is not, however, a historically accurate reconstruction.

Historically Accurate Oil Painting Reconstruction Techniques was a project that has set the research

standards for this kind of work. Known as HART for short, this kind of research methodology aims not

to recreate a perfect facsimile of the past, but acknowledge that some things have different

compositions in our own time that the researcher has to deal with appropriately.62 In this case we are

faced with the alchemical kilns described in this chapter, verses modern lab equipment. In addition,

other factors, like difference in egg make-up in today’s markets from changes in agriculture practices,

must also be considered. However, what these literature references have brought is valuable to this

thesis

Here we are faced with a conundrum. The hypothesis is that the description of snow-white eggshell

lime in recipes was to be taken note of by practitioners. Modern science seems to back up the idea

both that eggshell lime is ‘snow white’, and that if it is under-burnt it is quite grey in appearance, and

not pure lime. However, there is no intent to reconstruct anything in these research papers, they are

modern science. We can only assume that the science is backing the hypothesis that eggshell lime is

whiter than other limes. This hypothesis is important as its repeated mention in historical literature

makes it a likely reason that eggshell lime was chosen above other limes. If it is in fact true that this

materials whiteness is a reason to chose it in alchemical and artistic recipes, that is one answer to the

original research question of this thesis: Why would an artist or colourman process eggshells by

burning to make pigments, when there are many other ways to make lime?

To summarize the previous sections, although science does support the alchemical descriptions of the

eggshell lime, these particular research papers do nothing to even acknowledge alchemical practice.

Ideally, to fully understand the history of a material, we would also want to understand the practice

61 Suresh Patil, D. Jadhav Swati and M. B. Deshmukh, “Calcined eggshell (CES): An efficient natural catalyst for Knoevenagel condensation under aqueous condition” J. Chem. Sci. 125, No. 4, (2013), 851–857. 62 Leslie Carlyle and Maartje Witlox. “Historically Accurate Reconstructions of Artists’ Oil Painting Materials.” Tate Papers 7, Spring 2007 (2007).



29

behind its creation. Therefore, reconstruction of an alchemical calcination process on chicken

eggshells as one step in a longer artistic recipe reconstruction would be useful for further research. A

firsthand experience in this regard could help us better understand how likely it was that calx of

eggshells was purchased by artists ready-made or was made at home.



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Chapter 4: Eggs and the Alchemists

Written Sources Dating recipes containing eggshells/eggshell lime

In this research, it was found that alchemical recipes have contained eggs and well as eggshell lime.

The list is rather extensive, but the above reference to Paracelsus’ Aurora can be investigated again.

In describing the search for the “universal tincture”, or Philosopher’s Stone, Paracelsus describes

failures of formulations from previous alchemists to reach that goal: “…others in Hen-eggs, and in

milk, and in the Calx of Egg-shells, with all which they thought to have fixed Mercury”.63 Again the

specificity to hen’s eggs (sic), and thus their eggshells seems clear here.

Eggshells and eggshell lime are indeed found as ingredients throughout the alchemical corpus, for a

long time. It has been demonstrated above that this goes back to the Arabs, well before 1000 AD.

However, it seems that the Arabs did not invent this process. Now, we will briefly examine earlier,

pre-1000 AD, usages in alchemical recipes.

The alchemical historian Dafualt wrote an article about a contentiously attributed Greek alchemical

recipe, translated in English as “On the same divine water.”

A brief sketch of this recipe is: hard-boiled yolks and burnt eggshells are heated in an alembic over

the heat of a dung pile, the vapours captured and combined with egg yolks and recycled through this

process. Perhaps as the food spoils, the egg yolks are supposed to turn green at some point over the

days. The product is left heated by dung for 41 days, re-distilled, dried and then cast into silver to

complete the metal’s transmutation to gold. The idea that burnt eggshell and yolk could be code

names for some other materials is suggested. However, the alchemical manuscript source Marcianus

gr. 9.37-40 describes a very similar recipe using egg yolk, and yolk and shells mixed.64 Most

importantly to this research, the Beneficence and Success of the Creator recipe replaces the shells

with ordinary lime.65 Therefore, despite the dubious veracity of the process and outcome to modern

chemists, there does seem to be an understanding here that lime and burnt eggshells are the same

substance.

Now we must examine the thesis of Dafualt’s writing, the dating of the manuscript. His research

demonstrates that all dateable egg-distillation recipes are after 600 CE.66 Therefore the “On the same

divine water” recipe is in fact more modern than people had assumed, and may preclude any other

recipes being dated earlier.

It seems what is generally occurring in these recipes is that the transmutable egg was broken down

into its components (shell, yolk, white) which manipulated using heat and recombined in various

ways as part of the transmutation research. This apparently led to the fortuitous discovery of eggshell

63 Paracelsus, Paracelsus, his Aurora, 20. 64 Andrea Le Moli, Lela Alexidze, (eds), Prote Hyle: Notions of Matter in the Platonic and Aristotelian Traditions (Palermo, Palermo University Press, 2017), 12-13. 65 Ibid. 66 Ibid.



31

lime along the way. This was apparently first documented by the Greeks who were then copied by the

Arabs, before reaching early modern European alchemists.

Illustration Eggshell lime has been shown to be a crucial substance in alchemical recipes for centuries before it

found itself in pigment recipes. However, the question remains: why was eggshell lime specifically

such an important ingredient to the alchemists?

Alchemists were interested in the concept of transmutation of base metals to gold. Naturally this led

them to think about transmutation as a process in general. It is a nice metaphor to consider a chicken

egg being transmuted into a chick. As simple as a metaphor could be, this is not only ancient thinking

in the Eurasian cultural sphere, but perhaps could be described as pre-historic (pre- 4000BC). This is

evidenced by eggs in the creation myths of various cultures.67 Alchemists considered the process of

the hatching chick, which took time and the warmth of the hen sitting on it for the process to occur.

Similarly, many of the chemical reactions instigated by the alchemists took timed applications of heat

to instigate any reaction. This reasoning apparently inspired the symbolism of alchemical illustration

in the early modern era. All three illustrations discussed in this regard are from a 17th century book in

the Vatican Library, the Speculum Veritatis.

A typical example illustrating egg use in an alchemical context shows Vulcan being entrusted with the

Philosophic egg, so that “the chicken of the wise may hatch.”68 (Figure 15) Vulcan sits in front of a

symbolic forge with a tree growing out of the top. This is likely a metaphor for an alchemical process

where the vessel filled with the reactants (the egg) is given to Vulcan (smelted/incinerated) for a new

product to be produced.

67 H. J. Sheppard, “Egg Symbolism in Alchemy”, Ambix, 6, 3, (1958), 140-148, DOI: 10.1179/amb.1958.6.3.140. 140. 68 Klossowski de Rola, Alchemy, Colour Plate 40.

https://doi.org/10.1179/amb.1958.6.3.140



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A similar illustration is perhaps more direct in that the adept is seen feeding a chicken in front of a

distillation apparatus, while the other holds an egg in one hand (Figure 16). The cockscomb on its

head indicate this is really a chicken that is being depicted, not some other fowl. The extended

metaphor here likely relates to a process of fermentation as a nourishment for the ingredients being

processed and birthed through the philosophic egg.69

The final illustration to be discussed is quite direct in its symbolism (Figure 17). The distillation tower

in the center shows birds escaping at out of the top, but still captured within the apparatus. Next to

this apparatus are hens sitting on their nests. This is likely referring to the heat being applied over

time to the ingredients in a distillation, as the hen provides heat to warm her eggs. This image

interpretation is in fact attributable to Paracelsus. A gentle, continuous fire for heating an alembic is

described by him as providing heat that “whereof is to be compared with (or to imitate) the heat of a

hen, sitting upon her Eggs.”70

One should remember that despite many other possibilities, the references seem to be specific to

common hen’s eggs. This summarizes the symbolic role that the chicken egg plays in alchemical

illustration, as eggshells were an important ingredient in alchemy.

69 Ibid, Colour Plate 48. 70 Paracelsus, Paracelsus, his Aurora, 29.



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Modern Scientific View Chicken or Fowl? Then and Now

Having explained the role chickens and their eggs played in alchemy it is now pertinent to expand on

this to better understand what the eggshell ingredient in artistic recipes actually is. This will help both

with making informed reconstructions and understanding the choices artists made in creating these

recipes. The state of the art is best described in the Pigment Compendium. In this book, eggshell as a

pigment is described as being from “probably generally Gallus domesticus (chicken) egg.”71 This

leaves a lot of room for interpretation. No other artistic references before modern times specify what

fowl specifically provides the eggs. The purpose in this section is to further investigate this question in

detail.

What in the alchemical recipe literature can we find about the bird behind the eggshell source? The

Art of Chymistry: As it is Now Practiced (sic) (1668) describes this in detail. Newman, in 1994, and

others since, have supported the view that chymistry (the 17th century accepted spelling of the

modern English word) should be seen as overlapping with alchemy.72 This book, in translation from

the French, is by P. Thaibault, ‘chymist to the French king’.73 The author’s title seems to fit an

archetypal image of the profession of alchemy. His instructions for the preparation of eggshell lime

are clear. The first qualification is that you “must” use hen’s eggs, not duck, geese or turkey eggs,

because hen’s eggshells are thinner than duck eggshells.74 The reason given for this is that. This is

alleged to make them easier to calcine. The description given is that the chicken is a more temperate

animal than water fowl; since water fowl are “hotter,” the shell comes out of the animal thicker.75

The hotter temper in it makes it more difficult to affect its calcination. Also interesting is that the

hen’s eggshell calx produced by calcination is described as whiter than others. Lastly this product is

said to be useful as it contains much of the “white virginal earth”, which apparently has esoteric

meaning.76 Eggshells as a representation of the Classical ‘earth’ element will be discussed further in

Chapter 5.

As described in the introductory chapter, today there is a kind of ‘eggshell renaissance’ in the world of

green chemistry, that can help us understand the alchemical processes. Although there are many

publications available on chemical analysis of eggshell lime, one, which investigates duck eggs is

worth discussing. The researchers are located at a university in Bangkok. In the method section of the

paper, it is said that a local cafeteria was the source of the duck eggshell for the experiment.77

Although not described, it is assumed the chicken eggshells for the comparative work was also

sourced there. This would naturally raise questions about the applicability of this publication towards

71 Eastaugh, Compendium, 153. 72 "chemistry, n.". OED Online. March 2019. Oxford University Press. https://www-oed-com.proxy.uba.uva.nl:2443/view/Entry/31274?rskey=Iv1ica&result=1&isAdvanced=false (accessed May 25, 2019). 73 Thaibault, The Art, Title Page 74 Thaibault, The Art, 208. 75 Ibid. 76 Ibid, 209. 77 N. Tangboriboon, R. Kunanuruksapong, A. Sirivat, “Preparation and properties of calcium oxide from eggshells via calcination”, Materials Science-Poland, 30, No. 4, (2012) 313-322, 314.



34

our European art research. However, the mallard (Anas platyrhynchos) is considered a cosmopolitan

species. It is found naturally from Russia and Europe to China and across Canada, even in Australia.78

The mallard is thought to be the ancestral of all domestic ducks, except Muscovy duck, (Anas

moschata) in spite of the name being located in Central America. So, a Thai duck egg for our purposes

is presumably the same thing as a duck egg in Europe. The researchers do address this point,

describing how “breeding and feeding” impact the behavior of the shell produced by each bird in

their experiments.79 As described centuries ago, the duck eggshell is indeed thicker than the hen’s.

However, this was found to have no influence on the outcome of the calcination reaction

temperature and time.80 What did occur was a difference in the product. First, because of the

toughness of the shell, more moisture is retained during the calcination reaction. This means that the

duck’s eggshell lime contains traces of calcium hydroxide, which is absent in the hen’s eggshell lime

prepared under the same conditions, as proven by X-ray diffraction.81 The other property, also

affected by the raw shells thickness and density is the particle size of the final product. Duck eggshell

lime particles have a mean diameter of 29.16 um, whereas chicken eggshell lime value is 193.54 um.82

Also, while the true density of raw duck eggshell (2.25 g/cm3) is similar to chicken eggshell (2.20

g/cm3) the limes produced under the same conditions are 2.84 g/cm3 and 2.16 g/cm3 respectively.83

The simple conclusion is that, under the same conditions of production, duck eggshell lime is finer

and denser than chicken eggshell lime. This is logical, since a glass of sand is denser than the same

glass filled with pebbles, as the sand can better fill up the volume without leaving gaps.

Here we can also discuss what amounts of materials are involved, as one duck egg by nature will

supply more shell than one chicken egg. As the calcination process drives off the proteins and carbon

dioxide from the shell, the mass of lime produced in calcination of shell is less than the starting mass,

so this could potentially have an impact on the applicability of small shells to recipe creation. What is

in the literature about this? Unfortunately, Thiabault’s instructions say only to use “a good amount of

shells” to calcine.84 So, unfortunately, no more can be said about shell material amounts in calcination

recipes, with the information found in my research.

Another point of interest observed by the researchers is that duck eggshells, once heated to create

lime “stink” until the product is heated to 900°C, when it becomes odorless and white.85 The

interesting thing is that no other artistic or alchemical recipe consulted in my research mentions this

fact, something one would assume was noted more by writers of past times than contemporary

scientists.

In conclusion, this section provides more evidence to the eggshell in recipes referring to chicken

eggshell. This is valuable to this thesis and beyond, learn from this to interpret alchemy carefully.

78 DigiMorph Staff, 2004, "Anas platyrhynchos" (On-line), Digital Morphology http://digimorph.org/specimens/anas_platyrhynchos/skull/ Accessed June 2, 2019 79 N. Tangboriboon, R. Kunanuruksapong, A. Sirivat, “Preparation”, 317. 80 Ibid, 320. 81 Ibid, 321 82 Ibid, 317. 83 Ibid 84 Thaibault, The Art, 208. 85 Ibid, 315-16.

http://digimorph.org/specimens/anas_platyrhynchos/skull/



35

Although modern readers soundly reject the thought that ducks having a hotter temperament than

chickens could influence material science, the alchemists sometimes do have valuable observations

for us. The thicker eggshell of ducks, and thus different qualifications to lime produced from it, has

been proven by modern scientific research. So, the alchemists were at least correct to be specific in

the choice of shell. It is unfortunate that we cannot get any direct proof that hens’ eggshell must

have been used in artistic recipes. However, since there is evidence that alchemists were influencing

artistic recipes and were specific in their choice, it is implied that artist’s recipes involving “eggshells”

refer specifically to hen’s eggshells.

Summary

In conclusion, the alchemists did indeed work extensively with eggshells, and used them alone or as a

source of lime, through the transformative process of calcination. Although used by the Arabs,

following the source back to early Gnostic or Greco-Roman sources has not yet been proven.

However, from 600 AD on, experiments were occurring with eggshells, mainly as a source of lime.

This clearly inspired the 15th century German pigment recipes, as well as the pharmaceutical store list

recorded. Even an early modern writer in the 18th century described the nature of calx and calcination

of eggshell in more alchemical terms. However, as modern chemistry got things right and described

chemical reactions, this would change. Despite this, we are now in an “eggshell renaissance” where

modern chemical engineers can capitalize again on eggshell calcination to give a very pure calcium

oxide for various applications.



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Chapter 5: Recipes: Artist and Alchemist It becomes clear when one investigates recipe sources that there are many recipes that make use of

eggshells. Also, the influence of the alchemists on recipe writing using eggshells is mentioned at least

once in the literature, but never elaborated on. This chapter reviews the uses of eggshell and

describes the influence alchemy had on these recipes.

Lazur and the Arabs Already mentioned above, Arabic alchemy, while not the first alchemy ever practiced, was crucial for

introducing the concept of alchemy to Europe. Jabir Ibn Hayyan was one their most important

writers, and a recipe of his will now be examined.

As could be expected for an 8th century author, dating the manuscripts we have from him is a “vexing”

problem.86 At such an early date, it is difficult to distinguish between originals and copies of

manuscripts. Now let us examine an excerpt of one of his recipes, translated in a 2000 publication,

from a manuscript in Istanbul: “…and the first thing in this subject is to take one ratl of pure white sal ammoniac

with is called balluri (the crystal-like), and not to take from it except the same purity

which I indicated, and take one ratl from good zinjar (verdigris) which is made from

sal ammoniac, muharraq copper and vinegar, and one ratl from the best quality of

white calx of eggshells. Pulverize each independently and then mix them and put the

mixture under the sun for some little time so that it will dry…”87

Now, for comparison is a 15th century German recipe for lazur blue:

“If you want to make a good lazur from eggshells, take burned eggshells as much as

you like, and take salmiac (sal ammoniac), and grind it in a mortar. And take verdigris

as much as you like, and it should be grated well on a stone. And if you want to make

good lazur take one part of verdigris and another part of salmiac, each the same

amount, and take two parts of eggshells. And mix everything well, and put some

vinegar into it that it becomes wet. And if you mix it well it will become good lazur.

Someone from Vienna assured me this.”88 (See Appendix I)

Although they are entirely different in outcome, they are using basically the same ingredients and

processing. The nature of the Arabic verdigris is apparently not the same as western verdigris due to

the sal ammoniac used in its synthesis, but the lime is the same. It cannot be said with certainty that

Jabir’s recipe directly inspired the later lazur recipes, but it is a possibility. What is clear is that Arabic

ingredients and techniques were influencing European artistic recipes, but how exactly this occurred

remains a mystery. What can be said is that Jabir’s writings became Latinized, likely through Arabic

influence in Spain and that the writings of Gerber were published in Germany by 1545 as Alchemiae

Gebri. The notable similarity between the two recipes quoted above indicates the possibility that

German artistic recipe writers at that time had access to Arabic texts in translation.

86Le Moli, Lela Alexidze, (eds), Prote Hyle 14. 87See footnote 54 88 Krekel and Polborn, “Lime Blue” 174



37

Here we can explore the interpretation of secondary sources in translation as described in Appendix I.

What is the original text written in the Amberger Malerbuch? This could be accessed in transcription

and facsimile. So, comparing the original 15th Century German handwriting to someone else’s English

translation, could help interpretation of the text. For example, how the pouring of the wine vinegar is

written should be noted, as it is different to modern German. Also, it seems that modern German

readers may not even understand that this recipe is in fact from a Viennese source, due to alternative

spellings. For this thesis, we will assume that the recipe is originally sourced from Vienna, as Krekel

and Polborn translated it. Interpreting Arabic language manuscripts was not possible within the

constraints of this thesis, but could be helpful in future research. A final note is that the German

recipe came with assurance from “someone from Vienna”, suggesting that some of the Arabic

influenced recipe transmission occurred orally, not through manuscripts or printed books.

Eggshell White and Alchemy? Next, we will examine the most modern recipe found in the course of this research, so that we can

trace the concepts in it back to its origins. This is an eggshell white recipe from Constant de Massoul’s

A Treatise on the Art of Painting and the Composition of Colours from 1797. This book is perhaps the

first primary source text on pigments written by a colourman, as opposed to authorship by artists or

academics, and was first published in French.89 The English version acts as a catalogue for Massoul’s

business in downtown London. The appendix lists ‘white of eggshells’ as a pigment sold in his shop,

amongst a list of eighty pigments.90 The recipes in this book appear to be included as

information/advertising aimed at the artists who wanted assurances that they bought quality

materials. De Massoul writes that for those “who might wish to devote their time to the chymical (sic)

operations necessary in the preparation of colour,” his instructions are “too short.”91 This ‘disclaimer’

appears to be important since one asks: what businessman would tell you exactly how to make by

yourself what he is selling to you? Interestingly, the recipe indicates this is a pigment for ‘painting’

when most of the other recipes in his book indicated the different properties of the pigment,

between oil, watercolour and miniature painting. A facsimile of the recipe in in Figure 18.

89 Harley, Artist’s, 24-25. 90 Constant de Massoul, A Treatise on the Art of Painting and the Composition of Colours, (T Baylis, London, 1797), 232. 91 de Massoul, A Treatise, 229.



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As described in the previous chapter, lazur blue manufacture using eggshell lime was an important

use of eggshell in artistic practice. In the descriptions in the literature, some of those recipes also

clarify how to make eggshell lime itself. One 15th century recipe excerpt from England has been

reprinted.92 A facsimile of this is below (Figure 19)

Lye (sodium hydroxide) and lime (calcium hydroxide) function in water in a nearly identical way. They

are basic and caustic. So, to effectively dissolve away the membrane on the eggshell, it is logical to

use this kind of solution. It is also worth noting, the similar language around breaking up and drying

the product after the dirt is removed, that connects these two recipes and others.

Now, for comparison, we will look at a recipe from the Liber Illuministarum, describing how to make

calx of eggshells. This is reproduced below, in the original Latin text, and modern German (Figure 20).

Once again, a chemical additive is used to rid the shells of the membrane. In this case that is hot

lixinia (defined as lye, or technically a solution made from wood ash to use in soap).93 Notable in this

recipe is the use of lute (luti ingeninali, or, in other sources lutum sapientia) to encircle the vessel

containing the shells. Lute, in Middle English, is a kind of cement putty used to seal distillation

92 Mary Virginia Orna, J. D. Low Manfred and Norbert S. Baer, “Synthetic Blue Pigments: Ninth to Sixteenth Centuries. I. Literature” Studies in Conservation, 25, No. 2 (1980), 53-63, 58. 93 The Oxford Latin Dictionary, 1982 ed. s.v. “Lixivium”



39

apparatus.94 When used by the alchemists it is referred to as lutum sapientia (the lute of wisdom).

This shows there is a direct connection to alchemical practice in this recipe.

It is worth remembering, at least in the example shown in Figure 19, you would have a lead time of

almost a month to prepare one ingredient for the execution of your blue pigment recipe. Other

recipes shorten the cleaning process but still measure the time in the kiln in days. Surely this would

have impacted planning and work flow in the book illuminator/painter’s studio. In fact, this may have

a role to play in the likelihood that calx of eggshells was sold ready-made at apothecaries. On the

other hand, the fact that the calx preparation instruction was disseminated in these recipes suggests

many artists would make it themselves from scratch. In summary, the idea of cleaning eggshells with

a caustic solution to remove the inner membrane connects De Massoul’s recipe for eggshell white

and alchemical practice.

However, there were somewhat simpler instructions in old manuscripts, the example below being an

excerpt from The Book of the Secrets of Alchemy by Constantine of Pisa from the mid-13th century

(Figure 21).

In this case, no extra chemicals are involved with the lime production. However, the lute of wisdom

(and instructions to make this), are included in it. This supports the idea that the specific caustic

solution instructions found in the other two recipes is more than a coincidence. As before, this is so

much work to do, and time spent, to start your azure blue recipe. It is worth considering that time

was important a factor to the alchemists, and like good cooking, good alchemy took a long time. In

our own time, professor Lawrence Principe is a well-known authority on the history of alchemy.

During the writing of this thesis, there was an email communication with him on May 12, 2019. He

believes that times for calcination reactions described in alchemical recipes are exaggerated, and

mentioned current reconstruction experiments that, although purported to take eight days, took only

hours to complete. He also suggested the possibility that potters, who did fire for days, may have

94 "lute, n.2". OED Online. March 2019. Oxford University Press. https://www-oed-com.proxy.uba.uva.nl:2443/view/Entry/111435?rskey=mZ0ID6&result=2 (accessed May 16, 2019).



40

allowed alchemists (and artists) to include their experiments within a batch of pottery. So then, the

product could not be recovered until the potters removed their wares days later.

Another recipe for eggshell white is found in Dossie’s Handmaiden to the Arts, (1758) is presented

below (Figure 22). Although accomplishing the same task, it is much simpler, and appears to lack the

specific language about cleaning away membrane “dirt” and repetition of washing that is in all the

other recipes. However, the principle of membrane removal and washing clearly remains critical to

the process.

In summary, some recipes have a rather particular use of an alkali solution to remove the membrane

from the shell. This could suggest that a late 18th century recipe for eggshell white has some

connection to alchemical practice. The nature of the eggshell membrane in physical reality and

recipes will now be discussed in more depth.

Eggshell Membrane: Observations Since literature alone here would be insufficient to understand the eggshell membrane, and how it is

peeled; as supportive research for this thesis, white eggs were purchased and investigated (see

Appendix II). These recipes are from the late 17th to 18th century, but the knowledge of eggshell

membrane goes back earlier. The alchemist Paracelsus acknowledged eggshell membrane as a unique

ingredient in the early 17th century, indicating that this action of peeling to get pure membrane was

being used. Also, it suggests that the alchemists peeled eggshell when they desired to get shell,

recognizing shell and membrane as two separable entities. The results of the investigation confirmed

that the membrane is easily separated by peeling (Figure 22).



41

Nevertheless, this is a labour intensive process, and tricky to get right. Often, in my attempts to

separate eggshell and membrane, I found that the membrane rips and remains on the shell. This can

be observed as little bits stuck to the inner surface of the shell, which also have a slight sheen to them

(Figure 24). These shells, when stored in a closed container for a month, developed only the slightest

musty odor.

With a view to the recipe in Figure 18, other eggs were washed in ordinary tap water in the kitchen

immediately after cracking. Of course, “clean the eggs well” as described in the recipe is open to

interpretation. However, as a cracked egg’s inside remains quite wet with egg white, washing that

away with water made the most sense for a first approximation of the instructions. Unsurprisingly the

membrane remains intact on the inner surface after rinsing. What is a noteworthy observation is that

no odour developed from these shell pieces. This was observed after three weeks when the specimen

was left open to the air on a somewhat sunny window ledge and nearby bookshelf. In fact, the intact

membrane dries out like a piece of fragile parchment and remains as a shrunken film on the bottom

of the egg (Figure 25).

Although some of that parchment-like film detached from the shell, and could be shattered like glass

and discarded, most of the membrane remains firmly attached to the shell, again with a shiny finish



42

to it. Some of this dried film can be peeled off the shell if it is submerged under running water. This is

accomplished by rubbing the shell with your fingertips. However, most of the time the shell piece

simply fragments from the pressure of your fingers.

Overall it seems from investigation of real eggs that removing the shell membrane is possible, but

difficult to do by hand, as described in Dossie’s recipe. Also, it is not clear why you would do it, since it

can remain, and not create an odour. In particular, it seems a lot of work to do this, when your

product is going to be calcined. After all, one of the recipes takes ordinary quicklime to do this step,

when your product will be the same thing anyway. Finally, it is noteworthy that the modern scientific

eggshell lime production techniques never bother to remove the membrane before calcination.

In summary, it is possible that the overall concept of chemical removal of eggshell membrane came to

artistic recipes from alchemical practice. However, it remains unclear where the concept of removing

membranes by hand came from. Any membrane removal seems pointless if the shells are then to be

burnt to make lime. This is another reason to suppose that the inclusion of specific instructions to

remove the membrane being included in recipes in more than a coincidence.

Therefore, it is worth considering why the alchemists would be so interested in removing the

membrane from the shell for their recipes. Eggshell recipes for artists acknowledge the existence of

the inner membrane, and remove it, where some alchemical recipes remove it to use as its own

ingredient. When investigating the symbolic reasons why this might be, we find a reference to the

Turba Philosophorum, a classic alchemical text, the source Latin manuscript being in fact a translation

of an earlier Arabic source. In this book Pandolphus discusses the symbolic representation of the four

elements in the egg: the yolk is fire, egg white water, and shell is earth.95 Membranes within the egg

represent air, between water and fire, and water and earth. The inner membrane, keeping the yolk

‘fire’ separate from white is the same in spirit as the ‘lower’ air that separates the shell from the

‘water’ of the white.96 So, we can assume that to keep the earth element of the shell pure, the

separate element of the membrane had to be removed, in both alchemical recipes.

More interesting relations to artistic practice can be found in alchemical literature. In Paracelsus’

book, the mistakes of past alchemists are discussed. To fix mercury, he describes how “...others have

macerated the Membranes of Eggs in a most sharp Lixivium, wherewith they have also mixed calcined

Egg-shells (sic).”97 This is very intriguing on many levels to this discussion. Macerating membrane in

lixivium is an echo of the eggshell cleaning procedure described above. Also, this product is then

recombined with eggshell lime itself. This shows us that alchemists thought about eggshell, eggshell

lime, and membrane as individual substances. These were seen as separate entities that served

different functions in a recipe, or were deemed unnecessary, and thus required separation. Also, one

can see ‘’membranes of eggs’ as an ingredient to be macerated. What exactly is meant by the egg

membrane? As described in the Turba Philosiphorum, there are two possibilities, the one on the shell,

and the one that separates the yolk and white. Inside an egg, the membrane next to the yolk (the

95 Arthur Edward Waite (trans.) The Turba Philosophorum, (George Redway, London, 1896) 11-12 96Ibid. 97 Paracelsus, Paracelsus, his Aurora, 20.



43

vitelline) is very thin, about 12-24 microns, compared to the shell membrane which is over 70 microns

thick, although it itself is made of two distinct layers at the microscopic level.98

Once again to understand what exactly is being described by the alchemical recipes, observations

were carried out to compare reality to the writings. To this end, an egg was cracked in a dish and

dissected (Figure 26). The yolk membrane is obvious as it keeps the yolk together (B) When a yolk is

pierced, it is possible to recover a semblance of a pure yolk membrane, but it is quite fragile (C-E).

Since, by comparison, the shell membrane is relatively robust, it makes sense that it would require

maceration as opposed to being dissolved. In summary, one cannot be certain if the egg membrane

removal by lixivium-based recipes found between Paracelsus and the earlier Liber Illuministarum are

actually derived from the same source, but it is a distinct possibility. In conclusion, both artistic and

alchemical recipes describe the removal of membranes from eggs. It is proposed that both are

referring to the eggshell membrane, although alchemists were aware of the secondary membrane

between yolk and white. As often happens in alchemy these membranes also serve the symbolic

function of air, amongst the three other elements in eggs. The use of lixivium to separate shell and

membrane in both alchemical and artistic recipes again shows that these recipes are connected.

However, in some cases it is unclear as to whether the alchemists wanted to isolate yolk membrane,

or shell membrane.

98 T. Moran and H.P. Hale, “Physics of the Hen’s Egg: Membranes of the Egg” Journal of Experimental Biology 13, No. 1, (1935) 35-40, 36-37.



44

Discussion and Final Conclusions The research question from the introduction asks why would an artist or colourman choose to use

eggshells in a recipe in preference to other forms of chalk. What has been shown from a historical

research viewpoint is that alchemy was the inspiration for that decision. The artistic properties of

these materials were not investigated in this thesis. However, the materials in question were tracked

across time and space. Why was there such a focus on the processing of eggshells into lime in these

recipes? The reason is the alchemical tradition, but more could be said about this historically and

scientifically. The alchemical tradition is well documented, and so the eggshell and lime made from it

could be found throughout sources on early modern alchemy. Indeed, this is often referenced in the

writings of Paracelsus, an important early modern writer and alchemist. This carried on in the

literature to the 18th century writers of “chymistry” as the hermetical field of alchemy found parts of

its practice adsorbed into the beginnings of today’s chemistry. Finding the origins of this material in

alchemy also proved revelatory. An original Arabic source (in translation) showed this ingredient does

have a long history. This makes sense as the word alchemy itself comes to English from Arabic.

However, other sources from the even earlier Greek tradition also mention eggshell and eggshell

lime. So rather than just identifying the alchemists as users of eggshell lime, a more accurate history

of the material across time and place could be written. Information on this transfer of knowledge is

helpful in understanding how this ingredient has been used in artistic recipes.

The mass movement of people may have had an effect on the transfer of this knowledge. Why did the

Italians not make use of eggshells and the lime made from them in their recipes the way the Germans

did? Italians did have access to marble as a calcium carbonate source, and were not as inspired by a

direct contact with Arabic alchemy as those near Spain were. These two factors may be the reasons

why this occurred. Arabic influence in Europe reached as far as the border with France in the early

Middle Ages. Alchemical texts were widely translated into European languages in Toledo and other

centers of learning at this time. This activity brought alchemical knowledge north of the Alps to the

regions where the eggshell recipes were written faster than it could reach Italy. Furthermore, the

Italians had ready access to marble dust to produce lime, and so had no need of the eggshells to

produce lime. Perhaps in Italy the requirement of large amounts of lime for fresco, meant there was

no extra need for eggshell recycling? This is possible, but of course Italian artists could also have

eggshells left around from egg tempera production. Finding sources for eggshells generally also brings

to mind an anecdote of one of the first uses of walnut oil in painting by Giotto. While he was painting

for the Duke of Savoy in 1325, unusable oil for painting was passed on to the ducal kitchen.99 Simply

put, from the earliest times artist workshops could well be connected to kitchens to supply materials.

Then, if required, eggshells would have been readily available regardless. The flip side of the above

question about Italian eggshell use is also relevant: Why was eggshell lime more prevalent in

Germany than elsewhere? This is not easy to explain. However, the monasteries are important in the

Middle Ages for transferring knowledge, including alchemy, through manuscripts, as well as

illumination of those manuscripts. Eggshells would have been around those studios, since glair (egg

white) is important as a medium and adhesive in traditional bookmaking. It is worth considering that

99 Gettens and Stout, Painting, 42.



45

those shells could be recycled into other recipes. So, the difference between the use of eggshell in

Italy as opposed to Germany is explained by the alchemical text transfer.

In terms of science, contemporary research did offer a unique perspective on the material eggshell

lime to this thesis. However, this did not occur in a way typical of technical art history. The inspiration

to the research quoted was economical/environmental, not for historical or artistic research. In the

usual situation, a reconstruction of a recipe or material is completed and analyzed, with some intent

to have historical accuracy. In the present, we only assume that the connections between alchemical

observation and the modern science are true. In other words, the scientific literature here acts as a

reconstruction of an alchemical recipe technique, even if it was nothing of the sort originally. This

research technique did offer evidence that the alchemical technique of making lime from eggshells

does make sense according to modern science.

Through illustration, and literature material we see that there were reasons for chicken eggshells

specifically to be used over other bird eggs. This will help our understanding, and reconstruction of

the actual pigments from eggshells. This in turn will aid our knowledge of pigment recipe invention

and codification in the Medieval into early modern period. It is well known that orpiment (auri-

pigmentum is the golden pigment) naturally enticed the alchemists as an ingredient far back in time,

as artists also used it.100 Also, mercury and sulphur were critical to alchemical research and the

alchemists thus invented the important red pigment vermillion in the Middle ages.101 Now it seems

certain that eggshell lime can be added to the list of artist materials sourced from alchemical

laboratories. Furthermore, this thesis shows that eggshell white itself most likely draws on the

alchemical tradition in its preparation. However, it seems that the meaning behind the egg in

transmutation theory did not come to artist’s recipes with this alchemical process. In all, this thesis

has shown that even as simple an ingredient as eggshell in artistic recipes can have a long and rich

history behind it.

100 Thompson, The Materials, 177. 101 Ibid. 103.



46

Appendix I: Investigating the Translation of a Recipe Source Commentary on: Christoph Krekel and Kurt Polborn, “Lime Blue- A Medieval Pigment for Wall

Painting?”, Studies in Conservation 48 No. 3 (2003), 171-182. 174.

Original Source: Cod. 77, Amberger Malerbüchlein Page Number: f. 225r Location, Amberg,

Staatlichen Provinzialbibliothek

Facsimile:

Source: http://artechne.hum.uu.nl/node/86849?order=title&sort=desc

Transcription of Mittelhochdeutsch text

Source https://arb.mpiwg-berlin.mpg.de/node/86849

Wil dw machen guet lazur von den ayerschalen so nim geprant aier schalen alz vil und dw ir haben wilt

und nim den sal armoniacum und stoz daz chlain in ain morser und nim den spengruen alz vil dw des

wilt und scholt dÿ klain zer stozzen auff einem reibstain und wen dw wilt machen gut lazuer so nim ein

tail spens gruen und daz ander tal sal armoniak ains als alz vil als des andern und nim den aier schalen

alz vil der zwaier taÿl ist und temper es undereinander und geuz ein winick wein ezzeich dar under daz

es wol feucht werd und ruer es under einander so wirt es gut lazuer daz hat einer pewert zw win

http://artechne.hum.uu.nl/node/86849?order=title&sort=desc

https://arb.mpiwg-berlin.mpg.de/node/86849



47

Annotations by Julia Wagner, edited for clarity (Disclaimer: not an actual Mittelhochdeutsch translator)

Wil dw machen guet lazur von den ayerschalen so nim geprant102 aier schalen alz vil und dw ir haben

wilt und nim den sal armoniacum und stoz daz chlain in ain morser und nim den spengruen103 alz vil dw

des wilt und scholt104 dÿ klain zer stozzen 2auff einem reibstain105 und wen dw wilt machen gut lazuer

so nim ein tail spens gruen und daz ander tal sal armoniak ains als alz vil als des andern und nim den

aier schalen alz vil der zwaier taÿl106 ist und temper107 es undereinander und geuz ein winick wein

ezzeich dar under108 daz es wol109 feucht werd und ruer es under einander so wirt es gut lazuer daz hat

einer pewert110 zw win111

Christoph Krekel and Kurt Polborn, “Lime Blue- A Medieval Pigment for Wall Painting?”, Studies in Conservation

48 No. 3 (2003), 171-182. 174.

If you want to make a good lazur from eggshells, take burned eggshells as much as you like, and take

salmiac [ammonium chloride], and grind it in a mortar. And take verdigris as much as you like, and it

should be grated well on a stone. And if you want to make good lazur take one part of verdigris and

another part of salmiac, each the sam2e amount, and take two parts of eggshells. And mix everything

well, and put some vinegar into it that it becomes wet. And if you mix it well it will become good lazur.

Someone from Vienna assured me this.

102 Gebrant (= burnt) but not found as geprant: https://www.germanistik.uni-

bonn.de/institut/abteilungen/germanistische-mediavistik/studium/leitfaeden-reader-links/b1-reader-oktober-2009-endversion.pdf 103 Spengruen = Grünspan = Verdigris/Copper acetate https://books.google.nl/books?id=SbzmBQAAQBAJ&pg=PA2700&lpg=PA2700&dq=spengruen+spangrün&source=bl&ots=2dZD5eFEQc&sig=ACfU3U2ckPKHM5ipjgDchbaidlW7UX74YQ&hl=en&sa=X&ved=2ahUKEwitpqCZpubgAhVPJVAKHeKrDXsQ6AEwAHoECAIQAQ#v=onepage&q=spengruen%20spangrün&f=false 104 Could be an older version of “shall” http://woerterbuchnetz.de/DWB/call_wbgui_py_from_form?textpattern=&lemmapattern=sollen&sigle=DWB&lemid=GS16072&mode=Volltextsuche 105 „scholt dÿ klain zer stozzen auff einem reibstain“ may mean literally, “you should crush (or pound) it small on a grinding stone” but looking at “reibstain” it may mean muller or rubbing stone. 106 To me this sounds as if it means two parts of egg shells “so/as much as there is two parts” but not entirely sure about the medieval grammar 107 Tempern = to mix http://woerterbuchnetz.de/DWB/call_wbgui_py_from_form?sigle=DWB&mode=Volltextsuche&lemid=GT02140#XGT02140 108 Although I could not find definitions for “geuz” and “winick”, it sounds like nowadays “gieß” und “wenig”, so could mean “pour in a little wine vinegar” 109 Wol = good, very, well http://woerterbuchnetz.de/cgi-bin/WBNetz/wbgui_py?sigle=Lexer&lemid=LW04162 110 I could not find this verb but it is used in another text where it makes sense that it means something like “swear, guarantee or assure” https://archive.org/stream/mittelhochdeutsc00jeliuoft/mittelhochdeutsc00jeliuoft_djvu.txt 111 I could not find whether this really means “from Vienna” (aus Wien). Even though he spells wine as “wein” before, “win” can also mean wine and given the author also uses two different spellings for the word “small” (“chlain” and “klain”), I’m not sure what he means but overall it makes more sense that it means “someone from Vienna”.

https://www.germanistik.uni-bonn.de/institut/abteilungen/germanistische-mediavistik/studium/leitfaeden-reader-links/b1-reader-oktober-2009-endversion.pdf



https://books.google.nl/books?id=SbzmBQAAQBAJ&pg=PA2700&lpg=PA2700&dq=spengruen+spangrün&source=bl&ots=2dZD5eFEQc&sig=ACfU3U2ckPKHM5ipjgDchbaidlW7UX74YQ&hl=en&sa=X&ved=2ahUKEwitpqCZpubgAhVPJVAKHeKrDXsQ6AEwAHoECAIQAQ#v=onepage&q=spengruen%20spangrün&f=false



http://woerterbuchnetz.de/DWB/call_wbgui_py_from_form?textpattern=&lemmapattern=sollen&sigle=DWB&lemid=GS16072&mode=Volltextsuche

http://woerterbuchnetz.de/DWB/call_wbgui_py_from_form?textpattern=&lemmapattern=sollen&sigle=DWB&lemid=GS16072&mode=Volltextsuche

http://woerterbuchnetz.de/DWB/call_wbgui_py_from_form?sigle=DWB&mode=Volltextsuche&lemid=GT02140#XGT02140

http://woerterbuchnetz.de/DWB/call_wbgui_py_from_form?sigle=DWB&mode=Volltextsuche&lemid=GT02140#XGT02140

http://woerterbuchnetz.de/cgi-bin/WBNetz/wbgui_py?sigle=Lexer&lemid=LW04162

https://archive.org/stream/mittelhochdeutsc00jeliuoft/mittelhochdeutsc00jeliuoft_djvu.txt



48

Overall Coments from Ms. Wagner (via email)- This text was hard to read because the spelling,

grammar and word order is very different (from her modern German). It’s a bit like trying to understand

someone speaking in the deepest Swiss or Tyrol-accent. Overall, it appears that the (Krekel and

Polborn) translation is pretty good.



49

Appendix II: Modern Eggs, Historic Reconstructions?

For this thesis any egg investigated and shells gathered were purchased at the local Albert Hijn (Appendix Figure i). This clearly is not the same as the eggs in historic recipes. A few brief comments are below.

Figure i: Albert Hijn eggs. Author Photo

How are eggs today different than eggs of centuries ago? Today, eggs are produced very different than in pre-industrial times. Three different grades of eggs are sold in today’s supermarket, labeled with different requirements of feed and animal husbandry. Today’s commercial chickens are often more like machines inside large factory chicken coups constantly. The ones labeled free range (in English) seem to be the most like the eggs of yesteryear, since the chickens are free at times to eat whatever they choose outdoors, as we imagine animals were in the past. However, even this kind of egg will have differences in what they are compared to historic eggs from the breeding of the chickens over the years. There is no confusing which egg is which today as there is an indelible fuchsia stamp on all eggs (by law) bought at the supermarket today (Figure ii). It is not clear why there is a secondary stamp in the format of three letters and a pair of two digits separated by a hyphen also on this egg. Nicely for us, the eight- or nine-character mark offers information, as describe in the package (Figure iii). Although not depicted in Figure ii, some eggs shells collected in this project were from German eggs (i.e. stamped DE).

Figure ii: Stamps visible on any egg sold Figure iii: Guide to information on egg stamps in package. Author Photo in the EU. Author Photo

For a pigment reconstruction of eggshell white, the most concerning change of eggs over the

centuries is the presence of the fuchsia stamp. Otherwise this would likely just be incinerated in

production of eggshell lime. Other factors, meaning the breeding of the birds and exact diet, is out of

our control in reconstructions.



50

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