"Materials and Manufacture" in [catalogue] Mougins Museum of Classical Art

Materials and Manufacture

Murray Eiland

The Scientific Importance of Materials and Manufacture in the Ancient World At first sight the study of the meth-ods and materials from which antiq-uities were made may appear to be a specialised subject of very limited ap-plication. While the former assertion is true, the latter, as this chapter will attempt to show, is false. Questions ranging from authenticity through to age can be addressed using scientific techniques. The main focus will be high temperature materials from the Graeco-Roman world. This includes ceramics, glass, and metal.

One reason why it may be necessary to invest time and effort into a detailed characterization of these materials is that it may support or reject an ob-servation made by eye. An antiquity may appear slightly wrong, and only scientific methods can conclusively demonstrate it to be a forgery. While radio-carbon dating may be used for organic material, inorganic substanc-es present more of a challenge, espe-cially since forgers are becoming more adept. At the highest level they may be considered artists, and some of them combine talent with a keen interest in the past. Ancient glass has been faked for a considerable time with varying success. As archaeologists understand more about how ancient glass was made, forgers begin to incorporate the results of the latest research. More dif-ficult to reproduce is the aged surface of bronze vessels. Patina, layers of cor-rosion or dirt accumulated over cen-turies of burial, is notoriously difficult to replicate to fool careful microscopic examination.

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1. Terracotta bust of a goddess. Phrygian,

5th-4th century BC.Height: 25cm;Width: 17cm.MMoCA.32.

2. Terracotta figure of a male youth. Etruscan,4th-3rd century BC.

Height: 56.5cm;Width: 20cm.MMoCA.99.

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However, a problem looms in that many antiquities have been cleaned at some point in their life. On the one hand it makes them look better, on the other, over-cleaning obscures their burial environment and may put their authenticity in doubt. There is no sub-stitute for understanding how and from

what materials an artefact was pro-duced. The history of technology per se is also of great interest. It is not surpris-ing that most forged objects lie at the more expensive end of the current scale of value. The methods used to make an object in antiquity can also shed much light on what was valued in the past.

4. Terracottadoll. Parthian,

1st century BC - 2nd century AD.

Height: 23cm;Width: 7.5cm.MMoCA.147.

3. Red-figured neck amphora. Campanian,

circa 330 BC.Height: 41cm;

Diameter: 15cm.MMoCA.44.

5. Apulian red-figured hydria.Circa 320 BC.

Height: 51.5cm; Diameter: 29cm.

MMoCA.42.

6. Terracotta votive head of a youth. Etruscan,5th-4th century BC.

Height: 35.5cm;Width: 17cm.MMoCA.384.

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sels using the same technology. Areas designated as black were painted with a thick layer of clay. The firing process was complicated, and consisted of three stages. Each stage exploited the distinc-tive properties of iron that occur in the clay and glaze. During the first stage, air was introduced in the kiln, which was kept at 920-950°C, and the vessel

Greek PotteryRed-figured pottery was made between the sixth and fourth centuries BC (Figs 3, 5), and was inspired – in colour and in shape – from vessels in precious met-als that have rarely survived. While some of the finest painted examples originate from Greece, colonies in Italy produced quantities of red-figured ves-

7. Terracotta votivehead. Etruscan,

3rd-1st century BC. Height: 26cm;Width: 18cm.MMoCA.48.

8. Terracotta votivehead. Etruscan, 4th century BC. Height: 26cm;

Width: 18.5cm.MMoCA.49.


4th-3rd century BC.Height: 23.5cm;

Width: 14cm.MMoCA.151.


4th-3rd century BC.Height: 23.5cm;

Width: 14cm.MMoCA.37.

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retained the same reddish colour as the clay because of the formation of hema-tite Fe203. In stage two, green wood was added to the fire to reduce the oxy-gen. This turned hematite to magnetite Fe304 and the vessel turned black. In the third stage air was reintroduced into the kiln (reoxidation 800-850°C), and all areas that were not painted with a thick mixture of clay turned an orangy red. It is understandable why forgers of Greek vases have to surmount a num-ber of hurdles, both technological and artistic, before they can produce objects that could fool a specialist.

TerracottaFired clay figurines, masks, and other items in terracotta were popular with the Etruscans (Figs 2, 6-10), Greeks, Parthians (Fig 4), Phrygians (Fig 1), and Romans (Figs 11-14). Figurines became less favoured by the Romans, when bronze became more inexpen-sive. However, the tradition of making figurines in fired clay continued until the spread of Christianity in the Medi-terranean and Europe from the fourth century onwards. For much of this time figurines were of deities, and it is clear that as a rule their production was a craft and not an art. The clay used to produce them was the same as that used for everyday pottery with perhaps the addition of non-clay materials to reduce shrinkage when drying or firing. Egypt is well known for the quality and com-plexity of clay figurines during the Hel-lenistic period.

Figurines (Fig 15), as well as lamps (Figs 16-21), could be mass produced from one master (or archetype) that could itself be made of clay. In many

11. Terracotta theatre mask of a bearded hero .

Gallo-Roman,3rd-4th century AD.

Height: 32cm;Width: 17cm.MMoCA.100.

12. Terracotta theatre mask of a phylax.



13. Terracotta theatre mask of an old woman.



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figurines the back was made simply, and the front received the most at-tention. As a rule elaborate projec-tions were avoided, as they were dif-ficult to extract from the mould and fire in a kiln, but surface decoration could be elaborate. Moulds are rarely found, and when they are, they can be used by forgers to create new objects that can be difficult to identify with-out scientific methods of dating, such as thermoluminescence. Moulds were

usually made of plaster, and would absorb water in the wet clay that was pressed into it. Plaster moulds could yield 50 to 100 figurines, and when worn out, another mould could sim-ply be taken from an original. Simple figurines could be made from half a mould, while many were made from two halves that were joined while still wet. Examples have a seam run-ning down the middle. Many Greek, as well as some Roman, figurines

14. Terracotta plaque with an

Egyptianising scene in relief depicting a figure

that resembles Besamongst tendrils, flanked

by a male sphinxwearing a crown with a uraeus and a female

sphinx wearinga diadem.

Late 1st century BC.Height: 21.7cm;Width: 35.5cm.MMoCA.127.

15. Terracotta gladiators and a helmet.

1st-3rd century AD.Height: 22cm;

Width: 13cm (left figure).Height: 22.5cm;

Width: 10cm(right figure).

Height: 7.6cm;Height, Width: 8cm

(helmet).MMoCA.223.

would usually be covered with a clay slip in white (40, 41, 388). The ques-tion that emerges is what luxury mate-rial did terracotta imitate? In form as well many of these figurines are tall and narrow, perhaps evoking more expen-sive originals in ivory.

17. Terracotta oil lamp showing an erotic scene.

AD 175-225.Length: 10cm;Width: 7cm.

MMoCA.374.

16. Terracotta oil lamp depicting an erotic scene.

1st century AD. Length: 9cm;Width: 6.5cm;MMoCA.373.

18. Terracotta oil lamp depicting a gladiatorial

combat scene.1st-2nd century AD.

Length: 10cm;Width: 8cm.MMoCA.261.

19. Terracotta oil lamp showing an

animal scene.1st-2nd century AD.

Length: 10cm;Width: 7.3cm.MMoCA.261.

20. Terracotta oil lampdepicting a

gladiator helmet.1st-2nd century AD.

Length: 10.5cm;Width: 7.4cm.MMoCA.371.

21. Terracotta oil lampshowing a gladiator.1st-2nd century AD.

Length: 11cm;Width: 7.9cm.MMoCA.371.

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Roman Lamps Roman lamps in bronze survive, but as lighting was such an overriding concern, it is likely that even élite households had at least some ceramic lamps. Roman lamps were typically covered with a slip of a thin solution of the same clay that

made the body of the lamp. This coat-ing, fired in an oxidising atmosphere, appears reddish, and would have made the lamp less permeable to oil. Howev-er, replication experiments suggest that most lamps, unless they were fired at a high temperature, would be slightly per-

meable to oil. Greek lamps from about the sixth century BC were coated with a relatively impermeable black glaze. It appears that for ceramics, the average Roman lamp may have been inferior to the standard Greek lamp. It is also clear that Greek vase painting used methods

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that were, aesthetically at least, beyond that employed by the Romans. This does not suggest anything other than a change of value and taste over time.

Roman Luxury PotteryRoman luxury pottery is known for a moulded decoration and a glossy red surface (Figs 22-25). In order to obtain

a glossy surface, Roman potters pro-duced suspensions of illite to apply to the surface of the vessel. Illite is a clay mineral that has a flat structure and therefore lies flush against the surface of a vessel. If liquid clay is allowed to stand it will settle. Roman potters may have had several ways of producing the gloss, but it is likely that they selected

23. Terra sigillata jug in the form of the head of a

young girl and an inscription on the neck of the vessel

stamped: EX OFICINA OLITRISIS. AD 300-350.

Height: 23.5cm;Width: 11cm. MMoCA.106.

22. Ceramic cylindrical jug decorated with three

registers in reliefdepicting a hunt

and stamped:NAISIVS NAVISIVS.

3rd century AD.Height: 27.5cm;Diameter: 10cm.

MMoCA.105.

clay to be used for the coating and then used potash from wood ash. This ap-parently simple method was more so-phisticated than it would seem to the extent that forgeries of Roman gloss wares only began to be made recently.

As a rule, moulded pottery is viewed as mass produced, and Greek painted wares are appreciated as the product of artisans, whilst Roman wares tend to sell for less in the modern era. To the

ancients, however, both kinds of ves-sels were likely to have been of rela-tively low status compared to metallic vessels.

Roman Glass and FaienceRoman glass followed the general for-mula used in the Mediterranean since the emergence of glass in the middle of the third millennium BC. From first tentative steps in the first century BC, blown glass was produced in the Syro-

24. North Africanred-ware dish

depicting fishes anda hippocampus. 4th century AD.

Height: 3cm.Width: 27.5cm.MMoCA.391.

25. Terra sigillata bowl with vegetal decoration and rouletting, and an

inscription on theneck of the vessel

stamped: DARRA FE[CIT] AD 40-70.

Diameter: 25.3cm.MMoCA.472.

26. Sprinkler glass with opalescent iridescence.

3rd-4th century AD.Diameter: 4.5cm;

Height: 7.6cm.MMoCA.250.

27. Purple glass bottle.1st century AD.Diameter: 8cm;Height: 13cm.MMoCA.351.

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Palestinian region. By the first century AD, blowing glass vessels was the pre-dominant method of production. The tools required were limited. A special blowpipe was needed, as well as tongs, because the craftsman obviously could not directly handle hot molten glass. Production was more restrictive since a special kind of furnace was required to heat the glass enough for it to be ‘in-flated’ or blown through a pipe.

Fuel required to fire the furnace was a limiting factor, and it seems raw ma-terials were transported to sites with quantities of wood. Plutarch notes tam-arisk wood was ideal or coal. During this time glass vessels began to develop a distinctive répertoire of shapes that did not follow metallic or stone origi-nals. Roman glass is known for a vari-ety of shapes. Much of this was formed by blowing into a mould. Few of these

28. Green glass flaskwith vertical ribs.3rd century AD.

Diameter: 12.5cm;Height: 19cm.MMoCA.252.

29. Green glassconical flask.

4th century AD.Diameter: 7.2cm;Height: 14.5cm.

MMoCA.341.

30. Green glassamphoriskos.

1st-2nd century AD. Diameter: 15cm;

Height: 16cm.MMoCA.292.

31. Blue glassamphoriskos.

1st century AD.Diameter: 6.2cm;Height: 10.5cm.

MMoCA.350.

moulds survive, but the vessels indicate their method of manufacture. Much of the patterned mould-blown glass dates to the first century AD. In the second and third centuries square (Fig 35) and hexagonal bottles became increasingly common. Glass could also be formed by pinching ridges (Fig 45) as well as trail-ing glass of different colours along the surface (Figs 40, 48). Roman glass is a mixture of silica (sand, about 65-70%) and soda (approximate-ly 15%) as a flux, and lime (10%) which acted as a stabiliser. Glass with this com-

position would have a liquidus tempera-ture of 1000°C and a softening temper-ature of 700°C. The glass would have a very short working time, and only a skilled artisan with extensive training could handle its manipulation. Trail-ing glass of different colours as detailed above usually contains a higher amount of lead oxide. The glass recipe for trailed glass would have a lower melting tem-perature (depending upon the amount of oxide, but could be c. 750°C) and has a longer working time than clear glass. This gave an artisan more time to create elaborate trails with coloured glass.

32. Transparentglass beaker.

3rd-4th century AD.Diameter: 6.2cm;Height: 10.5cm.

MMoCA.369.

33. Transparent glass blue-green lidded jar. 3rd-4th century AD.

Diameter: 8.3cm;Height: 11.2cm.

MMoCA.370.

34. Blue-green glass ribbed bowl.

1st century AD.Diameter: 13.5cm;


35. Four-sided glass blue-green jug.

1st-2nd century AD.Diameter: 8.8cm;


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Lead rich coloured glasses could also be used for enamels. The key here is that the low melting temperature of the glass would not be high enough to melt the metal to which it was bonded. Much ancient enamel has perished, but many bronze objects, particularly from the fringes of the Roman Empire, were adorned with enamel that to modern eyes may appear gaudy. The Celts are particularly known for their enamelled metalwork. Most pieces were small, as powdered glass would be applied to a metal object and then heated in a furnace (which due to fuel constraints would usually be limited

in size). Little is known of the exact composition of Roman period enam-els because they are usually in a de-graded condition. Without soda, finished glass would be soluble in water, and glass, un-like ceramic, is easily damaged by water. Small amounts of water over

36. Turquoise faience dish. Romano-Egyptian,



37. Turquoise faience bowl. Romano-Egyptian,



38. Blue-greenglass bowl.



39. Green flask.1st century AD.

Diameter: 13cm;Height: 32cm.MMoCA.543.

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a significant period of time give glass an iridescent sheen that is prized by connoisseurs (Figs 26, 46). On the other hand, perfectly or nearly per-fectly preserved clear glass vessels are rare, but there are four excellent ex-amples in the Mougins collection: a beaker (Fig 32), jar (Fig 33), a rare funnel (Fig 47), and a splendid large glass storage jar (Fig 44). The result is that in the wetter parts of Europe ancient glass is recovered from stone coffins that have effectively sealed the objects from water. In the Mediterra-

nean fringe, in areas with less rainfall, glass can survive in a greater number of environments, but for obvious rea-sons some of the best examples are recovered from tombs. Akin to ceram-ics, the raw material for glass (sand) is commonly encountered. Crude glass may be made from sands from many areas. The rarest ingredient in Roman glass appears to be the source of soda alkali. For most Roman glass from the Mediterranean area, the most likely source of soda alkali is an evaporate mineral that occurs in the region of the

40. Green glass conical cup decorated with

black spotsof blue glass.AD 300-350.


41. Green glass swan.1st century BC.

Height: 6cm;Length: 17cm.MMoCA.565.

42. Green glass dish. 4th-5th century AD.

Diameter: 31cm;Height: 7cm.MMoCA.251.

43. Green glass plate. 2nd-3rd century AD.


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44. Pale blue glass storage jar.1st-2nd century AD. Diameter: 22.5cm;

Height: 24cm. MMoCA.289.

Wadi el-Natrun in Egypt. It is unclear if the alkali or the raw glass was trad-ed from this region.

Glass, like other luxury items, may have been traded long distances. The most common colour of Roman glass was a light blue-green because iron – which produces this effect – is present to some extent in most natural sand, two bowls (Figs 34, 38, and a jug (Fig 35) in the collection exemplify this. Other chemical agents could be added

to yield other colours. Copper could yield dark blue, green, or red depend-ing upon the furnace conditions (Figs 27, 29-31). Antimony was a very ef-fective decolouring agent of glass, manganese was less effective. These compounds may have been sourced from different localities and traded long distances.

Faience artefacts are attested in Egypt from Predynastic times. Faience is a non-clay based ceramic composed of

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crushed quartz or sand, with small amounts of calcite lime and a mixture of alkalis, with surface vitrification due to a soda lime silica glaze often com-posed of copper pigments to create a bright blue-green lustre. This tech-nique, and its variants, spread to many regions of the ancient world including Britain, Europe, and Asia. Two splen-did examples in the Mougins collection include a Romano-Egyptian bowl and dish (Figs 36, 37).

Roman BronzeBronze, detailed in Chapter 7, was of great importance in the Roman world. It was used for household items such as pots and pans, personal adornments, statuettes, and military implements

45. Green glassamphoriskos.

3rd-4th century AD.Diameter: 6cm;Height: 15.5cm.

MMoCA.278.

46. Amber glassjar with

opalescent iridescence.4th-5th century AD.

Diameter: 6cm;Height: 15.5cm.

MMoCA.249.

47. Green glass funnel. 3rd-4th century AD.

Diameter: 7.5cm;Length: 35.5cm.

MMoCA.478.

48. Blue-green glass storage jar with lead

trail decoration.4th century AD.

Diameter: 8.3cm;Height: 8.2cm.MMoCA.290.

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(Fig 50). Like so many other crafts, the workers left no written records of their techniques. The result is that their meth-ods and materials of manufacture must be studied not from literature, but from the objects themselves.

Copper in its pure state is very ductile, and in order to harden the metal addi-tives were used. When tin is added the resulting mixture is termed bronze. Tin was prized and it was obtained from dis-tant localities. The Greeks were aware of tin mined in Britain. Tin added in quantities making up to 13.2% of the mixture enabled the metal to be cold worked by hammering or stamping. Above this amount of tin, the metal becomes too brittle to be worked cold. Many bronze objects are made from sheets of bronze that have been ham-mered and then decorated with stamps. Armour usually falls into this category. Complex shapes could be hammered over a wooden form.

A bronze of copper and tin is not well suited to being cast, which is the usual way bronze sculpture and figurines are made (Fig 49). In order to make a liq-uid metal that flows fully into a mould, lead may be added. Lead also lowers the melting point of the metal, but it may also make it soft and unfit for cold working. Lead may be found in ceremo-nial weapons, but would not be ideal for objects of war. Bronze with over 3% lead content becomes softer, and above about 30% lead it is likely that it will separate from the copper. Bronze coins usually contained lead. Coin blanks when cast would need to be fluid in or-der to pour, and be fluid enough to expel any gasses.

49. Bronze statuette of Hermes (Mercury).

2nd-3rd century AD.Height: 9.3cm;Width: 3.3cm.MMoCA.477.

50. Bronze Thracianhelmet with

Phrygian crest.4th century BC.Height: 33cm.MMoCA.556.

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Additional bi-products of lead were the glazes that were developed to coat ceramic objects in domestic contexts in the Roman period. This was especially adapted to drinking vessels. Two such examples – skyphoi – in the Mougins collection are elegantly decorated with ivy vines, leaves, and flowers (Figs 51, 52). Lead would also make the metal more amenable to a die when struck. Some artefacts contained a very high content of lead or were fashioned entire-ly in this material. An excellent example of a cast lead object is the Phoenician sarcophagus in the Mougins collection (Fig 53).

Brass, a mixture of copper and zinc, could also be used for coins and other objects, such as armour. The colour of

the metal imitates gold, and although it could be cold worked, it was not well suited to being cast. Zinc easily volatises and is lost, so that the exact proportion of zinc in the mixture were not precisely controlled. Some objects, such as parade armour, that are corroded green today would have been highly polished and shining like gold. This effect would have been particularly striking in the helmets made of bronze (Fig 50), brass, or iron.

Gold and SilverSilver and gold in the classical world were used for a variety of purposes, from plate through items of adornment, statuettes, to coins (Figs 54-58). Consid-ering that gold was valuable and easy to melt, it is unsurprising that most arte-facts that survive are relatively small.

51. Ceramic skyphos with green lead glaze decorated with an ivy

vine. Roman,1st century AD.

Diameter: 6.2cm;Height: 4.6cm.MMoCA.463.

52. Ceramic skyphos with green lead glaze decorated with an ivy

vine. Roman,1st century AD.Diameter: 8cm;Height: 8.5cm.MMoCA.490.

53. Lead sarcophagus decorated in relief. Long

sides: a band of laurel leaves and Corinthian columns and dolphins, a Medusa mask, laurel

leaves with a seatedsphinx, bordered by a vine scroll; the panel

ends: a temple facade with four Corinthian

columns and a vase with vine tendrils, a pediment

roof of laurel with ivyleaves and a Medusa

mask roundel; an eight-armed cross with ivy leaves and a Medusa

mask roundel.Late Hellenistic - Early

Roman, Phoenicia,150 BC - AD 50.Height: 60cm;

Length: 171.5cm;Width: 41.5cm.

MMoCA.47.

54. Silver statuette of Aphrodite (Venus) Pudica, in a himation,

wearing a diadem.Her extended right hand

probably once heldan apple.

1st century AD.Height: 9cm;Width: 2cm.

MMoCA.696.

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It appears that it was the inherent value of these metals that played a dominant role in the ancient world. From metrical studies of surviving silver and gold ves-sels in the Greek sphere, it appears they were made in round figures according to the coinage standards of the region. Per-haps because of the vagaries of preserva-tion, few vessels were made according to the Attic standard. Most were made to follow either Persian or Thracian weight standards. This suggests that it was ob-jects of plate, and not coins, that served as the highest value media of exchange. Temples with their treasuries would have in effect served as state controlled vaults.

Today silver is regarded as very much less valuable than gold. In the early 1980s it stood at a ratio of about 1:83. However, circa 430 BC it was about 1:14. Roman conquests, through seizure of metals and possession of mines, as well as improve-ments in technology, resulted in precious metals flooding into the Empire. This is attested in the Mougins collection by a fine silver statuette of Venus Pudica, its modest dimensions make its craftsman-ship more remarkable (Fig 54).

However, there was always a drain: Gold and silver could be traded abroad for luxury goods as well as to appease barbarians. It is known that the purity of silver varied over time, according to the economic strength of the empire. Sil-ver could be purified so that it was sepa-rated (cupelled) from lead, leaving as little as 0.01% behind. However, most ancient silver contains traces of gold, which modern silver does not. This fact has been used to prove many suspect sil-ver objects are modern and not ancient.

Ancient silver coins usually had quan-tities of copper added to them, so that the silver was 95-99% pure in the Re-public and Early Empire (Figs 55, 56). Typical silver coins under Nero (AD 37-68) were 80% silver, 50% under Septi-mius Severus (r. AD 193-211), and only about 2% under Gallienus (AD 218-268). Some of the same techniques for altering the appearance of coins could be used for vessels and other objects as well. Mint authorities quickly found that the public was not eager to accept coins with a copper tone. To overcome this reluctance, mints placed their coins

55. Silver denariusdepicting the bust of

Caracalla; reverse, shows the personification of

Pax holding a branch and a sceptre. AD 215.Diameter: 18mm.

MMoCA.RC55.

56. Silver denarius showing the bust of

Maximinus I; reverse, Salus, the personification

of health, seated whilst feeding a snake.

AD 235-236.Diameter: 18mm.

MMoCA.RC56.

57. Gold solidusdepicting the bust ofLeo I; reverse, winged Victory holding a long

cross. AD 457-474.Diameter: 19mm.

MMoCA.RC57.

58. Gold solidus showing the bust of Anastasius;reverse, winged Victory

holding a long cross.AD 491-518.

Diameter: 19mm.MMoCA.RC58.

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in acid which leached copper from the surface. The layer of purer silver would take some time to begin to show wear, by which time the coin had progressed down a chain of ownership. For coins that were made with low concentrations of silver (or even perhaps of non-silver cores) the coin could be dipped in a bath of molten silver or silver chloride. There were in fact a number of ways of plating metal, and because gold and silver are so soft, military fittings were often plated. Iron and Steel Iron was first used in the latter part of the third millennium BC, but it was not used in quantity until about 1200 BC. The reason it was not exploited earlier relates to a relatively high melting point of 1535°C. The smelting point would have been around 1250°C. Iron must be separated from the chemical com-pound in which it occurs, the ore. For iron ores this involves removing oxy-gen and impurities. Massive amounts of charcoal were needed to provide fuel. It is likely therefore that most smiths ob-tained iron via trade. In nature copper is far less common than iron, but the technology to utilise it would prove to be the greatest difficulty. Iron could not be smelted into crucibles or cold worked like copper, but could be forged – joined together – while hot. The typical scene of a blacksmith standing or sitting at an anvil with hammer and tongs was a fa-miliar one in the Roman world.

Iron does not survive well in the archae-ological record, because it is especially susceptible to decay. However, it is clear that in the Roman period it played a vi-tal role. Everyday items, such as nails, were made in vast numbers. Weapons,

59. Iron spearpoints. Roman,

1st-5th century AD.Length: 9.5cm, 10cm,

10.3cm, 7.9cm.MMoCA.232.

60. Iron spearpoints. Roman,

1st-5th century AD.Length: 34cm, 26cm,

15cm, 28cm,27.5cm, 31.2cm.

MMoCA.232.

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notably arrowheads, bolts, and spear heads (Fig 59, 60) were widely produced. More complex objects, such as swords, were produced in specialised centres. There is no evidence that there was a detailed understanding of how steel was made. The ‘secret of steel’ is really quite simple in principle. Pure iron is relatively soft and unsuited for weapons or cut-ting tools. In order to harden iron, about one percent of carbon must be added. In some areas, such as in Roman Noricum (approximating to modern Austria), a natural steel was formed. Weapons from this region were prized (Fig 61). Wrought iron contains no more than about 0.5% carbon, but the amount of carbon can be increased by heating the iron in charcoal. The surface layers of the iron in such an instance are harder, as there is a ‘steel skin’. While smiths may not have un-derstood what they were doing, repeat-edly hammering and folding iron yields a layer cake structure of soft iron with bands of hard steel. Quenching the steel can make it very hard and brittle. If it is heated to a high temperature and slowly cooled it will become soft (tempered). A smith would be able to judge these tem-peratures on the basis of the colour of the hot metal. In practice it would have taken many years of training before a blade suitable for use as a sword could be made.

In many ways the march of technology in the ancient world revolved around high temperature industries. While the crafts of the potter and glassworker were different from the armourer, all these industries re-lied upon attaining and controlling heat. The Greeks and Romans understood this explicitly. According to Greek legend, the Titan Prometheus was the benefactor of humans. He stole fire from Zeus to give to humanity, for which he faced the pun-ishment of having his liver eaten by an eagle. He was celebrated in a small shrine in the potter’s quarter of Athens, not far from the Academy of Plato. This had its own altar dedicated to Prometheus. Ac-cording to the second-century AD Greek traveller Pausanias, this site was central to a torch race dedicated to the Titan. No stretch of the imagination is required to see the torch bearer as re-enacting the theft of fire from the gods. In many ways civilisation can be seen as a race through time with fire. Modern science is still coming to grips with the changes wrought by high temperatures. From ceramics through to glass and metals, high temperature industries continue to shape the modern world. As laboratory methods continue to elucidate the science behind antiquities, it is clear that art is also in a race, like technology. The two fields, at first so separate, may have more in common than is generally appreciated.

61. Infantry sword (spatha) ofthe Lauriacum type. Straight double-edged iron and steel blade with the characteristic

triangular point, with aDamascus pattern.

2nd-3rd century AD.Length: 83cm;Width: 5.8cm.MMoCA.138.

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"Materials and Manufacture" in [catalogue] Mougins Museum of Classical Art

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