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Lost-wax casting, sometimes called by the French name of cire perdue or the Latin cera perduta. It is the process by which a bronze is cast from an artist's sculpture; in industrial uses the modern process is called investment casting. An ancient practice, the process today varies from foundry to foundry, but the steps which are usually used in casting small bronze sculptures in a modern bronze foundry are generally quite standardized.

It is more appropriate to use the term "lost mould" rather than “lost wax” since the technique employs other materials besides wax, such as tallow, resin and tar ¹, and even textile. Because the mould is destroyed to unveil the cast item, the technique is also called ‘waste mould casting’ ², or the ‘waste wax process’ ³. One should be careful not to confuse it with other methods of casting, such the piece mould⁴, bivalve mould, or the open cast.

There are two types of lost-mould casting: solid and hollow (where a core is used). The ‘indirect method’ of lost-mould casting should be distinguished from the ‘direct method’. In the indirect process, the model is formed by moulds (often clay), so that the model can be repeated using the same moulds again and again (these moulds then, as normal, invested and lost, to make a mould for a cast).

Process

Casting jewellery and small parts

The methods used for small parts and jewellery vary a bit from those used for sculpture. A wax is obtained, either from injection into a rubber mold, or it is custom-made in wax. Occasionally, a custom-made wax might be molded in rubber first as insurance against the loss of the unique wax and related labor costs incurred in carving it. The wax or waxes are sprued and fused onto a rubber base, called a "sprue base". Then a metal flask, which resembles a short length of steel pipe that ranges roughly from 1.5 to six inches tall and wide, is put over the sprue base and the waxes. Most sprue bases have a circular rim which grips the standard-sized flask, holding it in place. Investment (refractory plaster) is mixed and poured into the flask, filling it. It hardens, then is burned out as outlined above. Casting is usually done straight from the kiln either by centrifugal casting or vacuum casting.

The lost-wax process can be used with any material that can burn, melt, or evaporate to leave a mold cavity. Some automobile manufacturers use a lost-foam technique to make engine blocks. The model is made of polystyrene foam, which is placed into a casting flask, consisting of a cope and drag, which is then filled with casting sand. The foam supports the sand, allowing shapes that would be impossible if the process had to rely on the sand alone. The metal is poured in, vaporizing the foam with its heat.

Textile use

In this process, the wax and the textile were both replaced by the metal during the casting process, whereby the fabric reinforcement would allow for a thinner model, and thus reduce the amount of metal expended in the mould ⁵. Evidence of this process is seen by the textile relief on the reverse side of objects and is sometimes referred to as ‘lost-wax, lost textile’. This textile relief is visible on gold ornaments from burial mounds in southern-Siberia of the ancient horse riding tribes, such as the distinctive group of openwork gold plaques⁶⁷. The technique may have its origins in the Far East, as indicated by the few Han examples⁸, and the bronze buckle and gold plaques found at the cemetery at Xigou ⁹. Such a technique may also have been used to manufacture some Viking Age oval brooches, indicated by numerous examples with fabric imprints such as that of Castletown (Scotland) ¹⁰.

History

Indirect literary evidence

Wax and modelling

Some early literary works allude to lost-wax casting. Columella, a Latin writer of the first century AD, mentions the processing of wax from beehives in "De Re Rustica," perhaps for casting, as does Pliny¹¹, who details a sophisticated procedure for making Punic wax. ¹²

One Greek inscription refers to the payment of craftsmen for their work on the Erechtheum in Athens (408/7-407/6 BC). Clay-modellers may be using clay moulds to make terracotta negatives for casting or to produce wax positives. ¹³ Pliny portrays¹⁴ Zenodorus as a well-reputed "ancient artist" of bronze statues¹⁵, and describes¹⁶ Lysistratos of Sikyon, who takes plaster casts from living faces to create wax casts using the indirect process.¹⁷

Bronze

One method of maximizing the qualities of molten bronze is to add a small amount of lead ¹⁸. Whilst we cannot fully assume that Pliny is referring to the lost wax casting method, it seems that the addition of lead was practiced specifically when using moulds. It is not certain whether the addition of lead was a conscious effort to make the molten bronze reach all the details of the mould.

Casting

Many bronze statues or parts of statues in Antiquity were cast using the lost wax process. Theodoros is commonly associated with bronze casting ¹⁹ making it appear more likely that Pausania²⁰ was mistaken in his identification of iron ²¹ in his reference to casting.

Quintilian enlightens us to the process of casting statues in their various parts, of which some of the moulds may have been produced by the lost wax process. The Berlin Foundry Cup (early fifth century BC) contains metalworking scenes of bronze statuary working, probably illustrating the indirect method of lost-wax casting²².

Direct literary evidence

Indian Sources

The lost wax method is well documented in ancient Indian literary sources. There is detailed information in the Silpasastras ²³ on casting images in metal, but it is the fifth century AD Vishnusamhita ²⁴ that refers directly to the modelling of wax for making metal objects in chapter XIV, where the translation reads “if an image is to be made of metal, it must first be made of wax” ²⁵. Chapter 68 of the ancient Sanskrit text Mānasāra²⁶ Silpa details of the casting of idols in wax and is entitled ‘Maduchchhista vidhānam’, which means, ‘lost wax method’ ²⁷²⁸. The Mānasollāsa (also known as the Abhilasitārtha chintāmani) was allegedly written by King Bhūlokamalla Somesvara (of the Chalukya dynasty of Kalyāni) in AD 1124-1125, and also provides detail about casting processes, specifically with references to the lost wax method ²⁹ ³⁰.

A late medieval treatise (belonging to the 16th century), the Uttarabhaga ³¹, also makes explicit reference to the lost wax method of casting. Written by Srïkumāra (a Kerala Brahmin), twenty-one verses (32-52) in Chapter II (entitled Linga lakshanam) detailed instructions are given on how to make a hollow casting³²³³.

Theophilus

Another author who writes knowledgeably on the lost wax process during the early medieval period is Theophilus ³⁴. In his treatise, Theophilus³⁵ provides step-by-step procedures for making specific articles, and it is some of these articles produced that employ the lost wax casting technique.

Theophilus gives detailed instructions³⁶. on the casting of the handles for making a chalice, as well as a the manufacture of ‘The Cast Censer’. Theophilus’ intimate understanding of the lost wax technique is evident in his ‘derivation of the weight of wax’. In Chapters 86 and 87 Theophilus provides detailed guidelines on how to carefully divide the wax into differing ratios, before moulding and casting, in order to achieve accurate audible tones when making small musical bells. It seems that early versions of Theophilus were at hand to the 16th century Florentine sculptor Benvenuto Cellini. Benvenuto Cellini used the lost wax method to cast his bronze Perseus ³⁷³⁸

The Conquistadors

The archaeological evidence informs us that the lost-wax process was well known to the Incas, the Aztecs and the Maya. This information also comes to us from the Spanish Writer ‘Releigh’ (AD 1596) who provides a brief account of casting carried out by the Aztecs³⁹.

Lost-wax process in archaeology

South Asia

The earliest casting of metals in India was known from around 3500 BC in the Mohenjodaro area ⁴⁰. The earliest known example of the lost-wax method is the Indian bronze figurine named the “dancing girl” found at Mohenjodaro, dating back nearly 5000 years to the Harappan period ⁴¹⁴². Pieces of animals, like the buffalo, bull and dog found from Mohenjodaro and Harappa, were cast by cire perdue ⁴³⁴⁴⁴⁵. A covered cart (with the wheels missing), and a complete cart with a driver, are two objects found from Chanhudaro that are also likely to be made by the lost-wax process ⁴⁶⁴⁷. Two copper figures discovered from the Harappan site Lothal ⁴⁸ were made by cire perdue ⁴⁹.

During the post-Harappan period, hoards of copper and bronze implements made by the lost-wax process are known from Uttar Pradesh, Bihar, Madhya Pradesh, Orissa, Andhra Pradesh and West Bengal ⁵⁰. Gold and copper ornaments, apparently Hellenistic in style, made by cire perdue are found at the Ruins at Sirkap. One example of this Indo-Greek art dates to the 1st century BC, the juvenile figure of Harpocrates excavated at Taxila ⁵¹. Bronze icons were produced during the 3rd and 4th centuries AD, such as the Buddha image at Amaravati, the images of Rama and Kartikeye in the Guntur district of Andhra Pradesh ⁵². A further two bronze images of Parsvanatha and a small hollow-cast bull were come from Sahribahlol, Gandhara, as well as the standing Tirthankara (2nd, 3rd century AD) from Chausa in Bihar ⁵³. Other notable bronze figures and images have been found in Rupar⁵⁴, Mathura⁵⁵, Pradesh and Brahmapura⁵⁶⁵⁷.

Gupta and post-Gupta period bronze figures have been recovered from the following sites: Saranath, Mirpur-Khas ⁵⁸, Sirpur⁵⁹, Balaighat⁶⁰, Akota⁶¹, Vasantagadh, Chhatarhi, Barmer and Chambi⁶² ⁶³. Producing images by the lost-wax process reached its peak during from 750 AD to 1100AD, and still remained prevalent in south India between 1500 AD and 1850 AD ⁶⁴. The technique still remains well practiced throughout India, as well as neighbouring countries Nepal, Tibet, Ceylon, Burma and Siam ⁶⁵.

East Asia

There is great variability in the use of the lost-wax method in South East Asia. The casting method of bronze during the Shang and Chou dynasties (approximately 1500BC to 500AD) has commonly been assumed to be by the lost-mould method ⁶⁶. Further investigations have revealed this not to be the case⁶⁷. The lost-wax technique did not appear in northern China until the 6th century BC ⁶⁸. Lost-wax casting is known as ro-gata in Japanese, and dates back to the Yoyoi period of c.200 BC ⁶⁹. The most famous piece made by cire perdue is the bronze image of Buddha in the temple of the Todaiji monastery at Kamakura ⁷⁰. It was made in sections between AD 743 and AD 749, allegedly using seven tons of wax ⁷¹.

Southeast Asia

Bangles⁷² made by the lost-wax process are characteristic of northeast Thailand⁷³. The inhabitants of Ban Na Di were casting bronze between 1200 BC and AD 200, using the lost-wax technique to manufacture their bangles ⁷⁴. Some of the bangles from Ban Na Di revealed a dark grey substance between the central clay core and the metal, which on analysis was identified as an unrefined form of insect wax ⁷⁵⁷⁶. It is likely that decorative items, like bracelets and rings, were made by cire perdue at Non Nok Tha and Ban Chiang ⁷⁷.

There are technological and material parallels between northeast Thailand and Vietnam concerning the lost-wax technique ⁷⁸. The sites exhibiting artifacts made by the lost-mould process in Vietnam come from the Dong Dau and Go Mun cultures ⁷⁹, such as one sickle and the figure of a seated individual from Go Mun⁸⁰, dating to the Go Mun phase⁸¹⁸².

The Near East

The lost-wax technique was used and developed for small-scale, and then large-scale, statues from c.3500-2750 BC in Mesopotamia, made of copper and bronze ⁸³. A small lion pendant from Uruk IV was cast by cire perdue⁸⁴, however, earlier lost-wax object examples come from the Nahal Mishmar hoard (Israel) made c.3700 BC ⁸⁵⁸⁶. The Sumerian metalworkers were practicing lost-wax casting from approximately 3500-3200 BC ⁸⁷. Much later examples from northeastern Mesopotamia/Anatolia include the Great Tumulus at Gordon (end of 8th century BC), as well as other types of Urartian cauldron attachments ⁸⁸.

Ancient Egypt

The Egyptians were practicing cire perdue from the mid 3rd millennium BC, shown by Early Dynastic bracelets and gold jewellery ⁸⁹⁹⁰. Inserted spouts for ewers ⁹¹ from the Fourth Dynasty (Old Kingdom) were made by the lost-wax method ⁹²⁹³. Hollow castings, such as the Louvre statuette ⁹⁴ appear during the Middle Kingdom, followed by solid cast statuettes (like the squatting, nursing mother, in Brooklyn) of the Second Intermediate/Early New Kingdom ⁹⁵. The hollow casting of statues is represented in the New Kingdom by the kneeling statue of Tuthmosis IV ⁹⁶ and the head fragment of Ramesses V ⁹⁷⁹⁸. Hollow castings become more detailed and continue into the Eighteenth Dynasty, shown by the black bronze kneeling figure of Tutankhamun ⁹⁹. Cire Perdue is used in mass-production during the Late Period to Graeco-Roman time when figures of deities are cast for personal devotion and votive temple offerings ¹⁰⁰. The nude-woman shaped handles of bronze mirrors are cast by the lost-wax process ¹⁰¹¹⁰².

Classical Greek and Roman, and the Mediterranean

The lost-wax technique was known in the Aegean during the Bronze Age, particularly in the second millennium BC ¹⁰³. Direct imitations and local derivations of Oriental, Syro-Palestinian and Cypriot figurines are found in Late Bronze Age Sardinia, with a local production of figurines from the eleventh to tenth century BC ¹⁰⁴.

Some Late Bronze Age sites in Cyprus have produced cast bronze figures of humans and animals, one example is the male figure found at Enkomi ¹⁰⁵. Three objects from Cyprus¹⁰⁶ were cast as by the lost-wax technique, from the 13th and 12th centuries BC, namely, the Amphorae Rim, the rod tripod, and the cast tripod ¹⁰⁷.

The cremation graves (mainly 8th-7th centuries BC, but continuing until the beginning of the 4th century) from the necropolis of Paularo (Italian Oriental Alps) contained fibulae, pendants and other copper-based objects that were made by the lost-wax process ¹⁰⁸. Etruscan examples, such as the bronze anthropomorphic handle from the Bocchi collection¹⁰⁹, dating back to the 6th to 5th centuries BC, were made by cire perdue ¹¹⁰. Most of the handles in the Bocchi clelction, as well as some Bronze vessels found in are of Adria¹¹¹ were made using the lost-wax technique ¹¹².

The better known lost-wax produced items from the classical world include the “Praying Boy”¹¹³ (c.300 BC), the statue of Hera from Vulci (Etruria)¹¹⁴, which, like most statues, were cast in several parts and then joined together ¹¹⁵. Other, earlier examples that show this assembly of lost-wax cast pieces include the bronze head of the Chatsworth Apollo, and the bronze head of Aphrodite from Satala (Armenia)¹¹⁶¹¹⁷. Geometric bronzes such as the four copper horses of San Marco ¹¹⁸ are other prime examples of statues cast in many parts ¹¹⁹.

Africa

Bronzes were produced in Africa by various Kingdoms, such as the Kingdoms of Benin, Yorubaland and the land of Ife in Nigeria, of which some portrait heads remain, all cast by the cire perdue process ¹²⁰.

Intermediate America

The lost-wax casting tradition was developed by the peoples of Intermediate Area of America ¹²¹¹²². Colombian (and lower Central American) metallurgy is characterized by the widespread use of lost-wax casting ¹²³. Lost-wax casting was rare in southern Ecuador and Peru as metal was primarily shaped by cold-working into sheet metal ¹²⁴. Two lost-wax moulds ¹²⁵ were found in a shaft and chamber tomb in the vereda of Pueblo Tapado ¹²⁶ and are dated roughly to the pre-Colombian period ¹²⁷. Some of the gold wire, and delicate wire ornament, such as the fine ear ornaments, typical of Intermediate America was made by cire perdue. The lost-wax process was employed for these prehispanic objects in both the Muisca and the Sinú cultural areas of ancient Colombia ¹²⁸. The lost-wax method did not appear in Mexico until the tenth century AD ¹²⁹. A wide range of bell forms from West Mexico were produced by cire perdue ¹³⁰.

Early Medieval Europe

The Gloucester candlestick (1104-1113 AD) was made intricately as a single piece wax model, which must have had a complex system of gates and vents to prevent air-locks, before being invested in a mould ¹³¹.

Gallery

Notes

^ Agrawal 2000: 45-46
^ McCreight 1991: 88
^ Maryon 1954:215
^ For a detailed explanation of piece mould casting, refer to Maryon (1954: 626-634) and Maryon & Plenderleith (1954: 630)
^ Bunker 1988: 222
^ housed in the Hermitage Museum, Leningrad
^ Bunker 1988: 222
^ Asian Art Museum of San Francisco
^ Zhungeer Banner, western inner Mongolia, 3rd-1st centuries BC
^ Smith 2005: 86
^ Natural History 21.83-84
^ Humphrey et al 1998: 382
^ Humphrey et al 1998: 335
^ History of Art 34.45-46
^ Jex-Blake & Seller 1967:32-5
^ History of Art 35:152-153
^ Jex-Blake & Seller 1967: 176-177
^ This will make the metal go further, and also improve the flow qualities of the molten metal, enabling it to reach all areas and parts of complex moulds (Hurcombe 2007: 207)
^ Pausania, Description of Greece 8.14.8 and Pliny, Natural History 34.83
^ In Pausania’s extract, it is believed that he may have mistakenly confused bronze with iron, because the furnaces would need to attain extremely high temperatures to melt the iron for casting in a mould (Humphrey et al 1998: 220-1)
^ Humphrey et al 1998: 221
^ Mattusch 1980: 435, 437
^ a text from the Gupta Period
^ an appendix to the Vishnu Purana
^ Kuppuram 1989: 119
^ The Mānasāra treatises were translated by Prof. P. K. Acharya, in which chapter 68 makes specific reference to the process
^ Krishnan 1976: 5
^ Kuppuram 1989: 121
^ Krishnan 1976: 1
^ Kuppuram 1989: 125
^ of the Śilparatna
^ Krishnan 1976: 3
^ Kuppuram 1989: 128
^ Believed to the Benedictine monk and historical metalworker ‘Roger of Helmarshausen’, Theophilus Presbyter was the Byzantine pseudonym he used when writing his treatise in the early to mid twelfth century (Hawthorne & Smith 1979: xv-xvii)
^ Theophilus’ work is not solely his own; his work includes copied information from other sources, such as the Mappae clavicula and Eraclius, De dolorous et artibus Romanorum (Hawthorne & Smith 1979: xviii)
^ The lost wax process is also used in Theophilus’ treatise for making ‘The Copper Wind Chest and Its Conductor’ (Chapter 84) and ‘Tin Cruets’ (Chapter 88). It is noteworthy to mention that in ‘Casting Bells’ (Chapter 85), Theophilus diverges slightly by using ‘tallow’ instead of wax, but nonetheless, is still working with the lost wax technique
^ M. D. 1944: 158
^ Krishnan 1976: 46
^ Krishnan 1976: 43
^ Kuppuram 1989: 7
^ Krishnan 1976:preface
^ Kuppuram 1989: 6-7, 14, 113
^ Krishnan 1976: preface
^ Agrawal 2000: 46
^ Kenoyer & Miller 1999: 126
^ Agrawal 2000: 46
^ Kenoyer & Miller 1999: 126
^ district of Ahmedabad of Gujurat
^ Kuppuram 1989: 113
^ Kuppuram 1989: 114
^ Kuppuram 1989: 114
^ Kuppuram 1989: 114
^ Kuppuram 1989: 114
^ in Punjab
^ in Uttar
^ in the Kolhapur district of Maharashtra
^ Kuppuram 1989: 114
^ Sind now in Pakistan
^ District of Raipur, M.P.
^ near Mahasthan now in Bangladesh
^ near Vadodara, Gujurat
^ in Rajesthan
^ Kuppuram 1989: 114
^ Kuppuram 199: 114, 118
^ (Krishnan 1976)
^ Krishnan 1976: 36
^ It is clear that the piece-mould casting method was the principal technique used to manufacture bronze vessels in China (Meyers 1988: 283)
^ White 1998: 180
^ Krishnan 1976: 37
^ Krishnan 1976: 39
^ Krishnan 1976: 39
^ They are virtually non-existent in second millennium China
^ White 1988: 180
^ Higham 1988: 134
^ Higham 1988: 134
^ White 1988: 178
^ Agrawal 2000:145-6
^ Agrawal 2000: 146
^ Agrawal 2000: 146
^ near Phung Nguyen, the Bac Bo Region
^ end of the General B period, up until the 7th century BC
^ Higham 1988: 142
^ Moorey 1988: 31
^ one of the earliest surviving lost-wax castings
^ Moorey 1988: 31
^ Muhly 1988: 423
^ Scheel 1989: 40
^ Azarpay 1968: 54-55
^ Ogden 1982: 73
^ Darling 1990: 62
^ copper water vessels
^ Ogden 2000: 158
^ Darling 1990: 62
^ from the Fayum find
^ Ogden 2000: 158
^ British Museum, London
^ Fitzwilliam Museum, Cambridge
^ Aldred 1980: 25
^ Museum of the University of Pennsylvania
^ Scheel 1989: 41
^ some examples at the Egypt Museum, Berlin, and the Kestner-Museum, Hanover
^ Scheel 1989: 42-43
^ LoSchiavo 1988: 101
^ LoSchiavo 1988: 101
^ Schorsch & Hendrix 2003: 47
^ held in the Metropolitan Museum of Art (New York)
^ Schorsch & Hendrix 2003: 49, 50, 52
^ Giumlia-Mair et al 2003: 158-160, 162
^ National Archaeological Museum of Adria
^ Bonomi et al 2003: 467
^ Rovigo, Italy
^ Bonomi et al 2003: 467, 471
^ in the Berlin Museum
^ held in the Munich Glyptothek
^ Neuburger 1930: 57
^ in the British Museum
^ Maryon 1956: 476-478
^ Venice, probably 2nd century AD
^ Darling 1990: 67
^ Krishnan 1976: 43
^ Nicaragua, Costa Rica, Panama, Colombia, northwest Venezuela, Andean America, or the western portion of South America
^ Lechtman 1988: 344
^ Hosler 1988: 340
^ Hosler 1988: 340
^ one complete, and one partially broken
^ in the municipio of Montenegro (Depart of Quindío)
^ Bruhns 1972: 308-311
^ Scott 1991: 65, 67
^ Hodges 1970: 239
^ Hosler 1988: 329
^ Maryon 1956: 480
^ Kuppuram 1989: 125

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