Lost-wax casting – also calledinvestment casting,precision casting, orcire perdue (French:[siʁpɛʁdy];borrowed fromFrench)[1] – is the process by which a duplicatesculpture (often ametal, such assilver,gold,brass, orbronze) iscast from an original sculpture. Intricate works can be achieved by this method.
The oldest known examples of this technique are approximately 6,500 years old (4550–4450 BC) and attributed to gold artefacts found at Bulgaria'sVarna Necropolis.[2] A copper amulet fromMehrgarh,Indus Valley civilization, in present-day Pakistan, is dated to circa 4,000 BC.[3] Cast copper objects, found in theNahal Mishmar hoard in southernIsrael, which belong to theChalcolithic period (4500–3500 BC), are estimated, fromcarbon-14 dating, to date to circa 3500 BC.[4][5] Other examples from somewhat later periods are from Mesopotamia in the third millennium BC.[6] Lost-wax casting was widespread in Europe until the 18th century, when apiece-moulding process came to predominate.
The steps used in casting small bronze sculptures are fairly standardized, though the process today varies fromfoundry to foundry (in modern industrial use, the process is called investment casting). Variations of the process include: "lostmould", which recognizes that materials other thanwax can be used (such astallow,resin,tar, andtextile);[7] and "waste wax process" (or "waste mould casting"), because the mould is destroyed to remove the cast item.[8][9]
Casts can be made of the wax model itself, the direct method, or of a wax copy of a model that need not be of wax, the indirect method. These are the steps for the indirect process (the direct method starts at step 7):
Prior to silica-based casting moulds, these moulds were made of a variety of other fire-proof materials, the most common beingplaster based, with added grout, andclay based. Prior to rubber moulds gelatine was used.
The methods used for small parts andjewellery vary somewhat from those used for sculpture. A wax model is obtained either from injection into a rubber mould or by being custom-made by carving. 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 3.5 to 15 centimeters 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 bycentrifugal casting orvacuum casting.
The lost-wax process can be used with any material that canburn,melt, orevaporate to leave a mould cavity. Someautomobile manufacturers use a lost-foam technique to makeengine blocks. The model is made ofpolystyrene foam, which is placed into acasting flask, consisting of acope and drag, which is then filled withcasting 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.
In dentistry, gold crowns, inlays and onlays are made by the lost-wax technique. Application of Lost Wax technique for the fabrication of cast inlay was first reported by Taggart. A typical gold alloy is about 60% gold and 28% silver with copper and other metals making up the rest. Careful attention to tooth preparation, impression taking and laboratory technique are required to make this type of restoration a success. Dental laboratories make other items this way as well.
In this process, the wax and the textile are both replaced by the metal during the casting process, whereby the fabric reinforcement allows for a thinner model, and thus reduces the amount of metal expended in the mould.[10] 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 ongold ornaments fromburial mounds in southernSiberia of theancient horse riding tribes, such as the distinctive group of openwork goldplaques housed in theHermitage Museum,Saint Petersburg.[10] The technique may have its origins in theFar East, as indicated by the fewHan examples, and the bronze buckle and gold plaques found at thecemetery at Xigou.[11] Such a technique may also have been used to manufacture someViking Ageovalbrooches, indicated by numerous examples with fabric imprints such as those ofCastletown (Scotland).[12]
The lost-wax casting process may also be used in the production of cast glass sculptures. The original sculpture is made from wax. The sculpture is then covered with mold material (e.g., plaster), except for the bottom of the mold which must remain open. When the mold has hardened, the encased sculpture is removed by applying heat to the bottom of the mold. This melts out the wax (the wax is 'lost') and destroys the original sculpture. The mold is then placed in a kiln upside down with a funnel-like cup on top that holds small chunks of glass. When the kiln is brought up to temperature (1450-1530 degrees Fahrenheit), the glass chunks melt and flow down into the mold.Annealing time is usually 3–5 days, and total kiln time is 5 or more days. After the mold is removed from the kiln, the mold material is removed to reveal the sculpture inside.
Cast gold knucklebones, beads, and bracelets, found in graves at Bulgaria'sVarna Necropolis, have been dated to approximately 6500 yearsBP. They are believed to be both some of the oldest known manufactured golden objects, and the oldest objects known to have been made using lost wax casting.[2]
Some of the oldest known examples of the lost-wax technique are the objects discovered in theNahal Mishmar hoard in southernLand of Israel, and which belong to theChalcolithic period (4500–3500 BC). ConservativeCarbon-14 estimates date the items to around 3700 BC, making them more than 5700 years old.[4][5]
InMesopotamia, fromc. 3500–2750 BC, the lost-wax technique was used for small-scale, and then later large-scale copper and bronze statues.[4] One of the earliest surviving lost-wax castings is a small lionpendant fromUruk IV.Sumerian metalworkers were practicing lost-wax casting from approximatelyc. 3500–3200 BC.[13] Much later examples from northeasternMesopotamia/Anatolia include the Great Tumulus atGordion (late 8th century BC), as well as other types ofUrartiancauldron attachments.[14]
The oldest known example of applying the lost-wax technique to copper casting comes from a 6,000-year-old (c. 4000 BC) copper, wheel-shapedamulet found atMehrgarh, Pakistan.[3]
Metal casting, by theIndus Valley civilization, produced some of the earliest known examples of lost-wax casting applied to the casting of copper alloys, a bronze figurine, found atMohenjo-daro, and named the "dancing girl", is dated to 2300-1750 BC.[15][16] Other examples include the buffalo, bull and dog found at Mohenjodaro andHarappa,[7][16][17] twocopper figures found at the Harappan siteLothal in the district of Ahmedabad of Gujarat,[15] and likely a covered cart with wheels missing and a complete cart with a driver found atChanhudaro.[7][17]
During the post-Harappan period, hoards of copper and bronze implements made by the lost-wax process are known fromTamil Nadu,Uttar Pradesh,Bihar,Madhya Pradesh,Odisha,Andhra Pradesh andWest Bengal.[15] Gold and copper ornaments, apparentlyHellenistic in style, made bycire perdue were found at the ruins atSirkap. One example of this Indo-Greek art dates to the1st century BC the juvenile figure ofHarpocrates excavated atTaxila.[15] Bronzeicons were produced during the 3rd and 4th centuries, such as theBuddha image atAmaravati, and the images ofRama andKartikeya in theGuntur district of Andhra Pradesh.[15] A further two bronze images ofParsvanatha and a small hollow-cast bull came from Sahribahlol,Gandhara, and a standingTirthankara (2nd~3rd centuryCE) from Chausa in Bihar should be mentioned here as well.[15] Other notable bronze figures and images have been found inRupar,Mathura (in Uttar Pradesh) andBrahmapura,Maharashtra.[15]
Gupta and post-Gupta period bronze figures have been recovered from the following sites:Saranath,Mirpur-Khas (inPakistan),Sirpur (District of Raipur), Balaighat (nearMahasthan now inBangladesh),Akota (nearVadodara, Gujarat), Vasantagadh,Chhatarhi,Barmer and Chambi (inRajesthan).[15] The bronze casting technique and making of bronze images of traditional icons reached a high stage of development in South India during the medieval period. Although bronze images were modelled and cast during the Pallava Period in the eighth and ninth centuries, some of the most beautiful and exquisite statues were produced during theChola Period in Tamil Nadu from the tenth to the twelfth century. The technique and art of fashioning bronze images is still skillfully practised in South India, particularly in Kumbakonam. The distinguished patron during the tenth century was the widowed Chola queen, Sembiyan Maha Devi. Chola bronzes are the most sought-after collector's items by art lovers all over theworld. The technique was used throughout India, as well as in the neighbouring countriesNepal,Tibet,Ceylon,Burma andSiam.[16]
The inhabitants ofBan Na Di were casting bronze fromc. 1200 BC to 200 AD, using the lost-wax technique to manufacturebangles.[18] Bangles made by the lost-wax process are characteristic of northeastThailand.[19] 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 ofinsect wax.[19][18] It is likely that decorative items, likebracelets andrings, were made bycire perdue atNon Nok Tha andBan Chiang.[7] There are technological and material parallels between northeast Thailand andVietnam concerning the lost-wax technique.[7] The sites exhibiting artifacts made by the lost-mould process in Vietnam, such as theDong Son drums, come from theDong Son, andPhung Nguyen cultures,[7] such as onesickle and the figure of a seated individual from Go Mun (near Phung Nguyen, theBac Bo Region), dating to the Go Mun phase (end of the General B period, up until the 7th century BC).[18]
Cast bronzes are known to have been produced inAfrica by the 9th century AD inIgboland (Igbo-Ukwu) inNigeria, the 12th century AD inYorubaland (Ife) and the 15th century AD in thekingdom of Benin. Some portrait heads remain.[16]Benin mastered bronze during the 16th century, produced portraiture and reliefs in the metal using the lost wax process.[20]
TheEgyptians were practicingcire perdue from the mid 3rd millennium BC, shown byEarly Dynastic bracelets and gold jewellery.[21][22] Inserted spouts forewers (copper water vessels) from theFourth Dynasty (Old Kingdom) were made by the lost-wax method.[22][23] Hollow castings, such as theLouvre statuette from theFayum find appeared during theMiddle Kingdom, followed by solid cast statuettes (like the squatting,nursingmother, inBrooklyn) of the Second Intermediate/EarlyNew Kingdom.[23] The hollow casting of statues is represented in the New Kingdom by thekneeling statue ofTuthmosis IV (British Museum,London) and the head fragment ofRamesses V (Fitzwilliam Museum, Cambridge).[24] Hollow castings become more detailed and continue into theEighteenth Dynasty, shown by the black bronze kneeling figure ofTutankhamun (Museum of the University of Pennsylvania).Cire Perdue is used inmass-production during theLate Period toGraeco-Roman times when figures ofdeities were cast for personaldevotion andvotive temple offerings.[13]Nudefemale-shaped handles on bronzemirrors were cast by the lost-wax process.[13]
The lost-wax technique came to be known in theMediterranean during theBronze Age.[25] It was a major metalworking technique utilized in the ancient Mediterranean world, notably during theClassical period of Greece for large-scalebronze statuary[26] and inthe Roman world.
Direct imitations and local derivations ofOriental,Syro-Palestinian andCypriotfigurines are found in Late Bronze AgeSardinia, with a local production of figurines from the 11th to 10th century BC.[25] Thecremationgraves (mainly 8th-7th centuries BC, but continuing until the beginning of the 4th century) from thenecropolis ofPaularo (Italian Oriental Alps) containedfibulae, pendants and other copper-based objects that were made by the lost-wax process.[27]Etruscan examples, such as the bronzeanthropomorphic handle from theBocchi collection (National Archaeological Museum ofAdria), dating back to the 6th to 5th centuries BC, were made bycire perdue.[28] Most of the handles in the Bocchi collection, as well as some bronze vessels found in Adria (Rovigo,Italy) were made using the lost-wax technique.[28] The better known lost-wax produced items from the classical world include thePraying Boyc. 300 BC (in theBerlin Museum), the statue ofHera fromVulci (Etruria), which, like most statues, was cast in several parts which were then joined.[29] Geometric bronzes such as the four copper horses of San Marco (Venice, probably 2nd century) are other prime examples of statues cast in many parts.
Examples of works made using the lost-wax casting process inAncient Greece largely are unavailable due to the common practice in later periods of melting down pieces to reuse their materials.[31] Much of the evidence for these products come fromshipwrecks.[32] Asunderwater archaeology became feasible, artifacts lost to the sea became more accessible.[32] Statues like theArtemision Bronze Zeus or Poseidon (found nearCape Artemision), as well as theVictorious Youth (found nearFano), are two such examples of Greek lost-wax bronze statuary that were discovered underwater.[32][33]
Some Late Bronze Age sites in Cyprus have produced cast bronze figures of humans and animals. One example is the male figure found atEnkomi. Three objects from Cyprus (held in theMetropolitan Museum of Art inNew York) were cast by the lost-wax technique from the 13th and 12th centuries BC, namely, theamphorae rim, the rodtripod, and the cast tripod.[34]
Other, earlier examples that show this assembly of lost-wax cast pieces include the bronze head of theChatsworth Apollo and the bronze head ofAphrodite fromSatala (Turkey) from the British Museum.[35]
There is great variability in the use of the lost-wax method in East Asia. The casting method to make bronzes till the early phase of Eastern Zhou (770-256 BC) was almost invariably section-mold process.[36] Starting from around 600 BC, there was an unmistakable rise of lost-wax casting in the central plains of China, first witnessed in the Chu cultural sphere.[37]Further investigations have revealed this not to be the case as it is clear that the piece-mould casting method was the principal technique used to manufacture bronze vessels inChina.[38] The lost-wax technique did not appear in northern China until the 6th century BC.[19] Lost-wax casting is known asrōgata inJapanese, and dates back to theYayoi period,c. 200 BC.[16] The most famous piece made bycire perdue is the bronze image of Buddha in the temple of theTodaiji monastery atNara.[16] It was made in sections between 743 and 749, allegedly using seven tons of wax.[16]
TheDunaverney (1050–910 BC) andLittle Thetford (1000–701 BC) flesh-hooks have been shown to be made using a lost-wax process. The Little Thetford flesh-hook, in particular, employed distinctly inventive construction methods.[39][40] The intricateGloucester Candlestick (1104–1113 AD) was made as a single-piece wax model, then given a complex system of gates and vents before being invested in a mould.[9]
The lost-wax casting tradition was developed by the peoples ofNicaragua,Costa Rica,Panama,Colombia, northwestVenezuela, Andean America, and the western portion ofSouth America.[41] Lost-wax casting produced some of the region's typical goldwire and delicate wire ornament, such as fine ear ornaments. The process was employed inprehispanic times in Colombia'sMuisca andSinú cultural areas.[42] Two lost-wax moulds, one complete and one partially broken, were found in ashaft and chamber tomb in thevereda of Pueblo Tapado in themunicipio ofMontenegro (Department of Quindío), dated roughly to the pre-Columbian period.[43] The lost-wax method did not appear inMexico until the 10th century,[44] and was thereafter used in western Mexico to make a wide range of bell forms.[45]
Some earlyliterary works allude to lost-wax casting.Columella, aRoman writer of the 1st century AD, mentions the processing of wax frombeehives inDe Re Rustica, perhaps for casting, as doesPliny the Elder,[46] who details a sophisticated procedure for makingPunic wax.[47] OneGreekinscription refers to the payment of craftsmen for their work on theErechtheum inAthens (408/7–407/6 BC). Clay-modellers may use clay moulds to maketerracotta negatives for casting or to produce wax positives.[47] Pliny portrays[46]Zenodorus [fr] as a well-reputed ancient artist producing bronze statues,[48] and describes[46]Lysistratos ofSikyon, who takes plaster casts from livingfaces to create wax casts using the indirect process.[48]
Many bronze statues or parts of statues in antiquity were cast using the lost wax process.Theodorus of Samos is commonly associated with bronze casting.[46][49] Pliny also mentions the use oflead, which is known to help molten bronze flow into all areas and parts of complex moulds.[50]Quintilian documents the casting of statues in parts, whose moulds may have been produced by the lost wax process. Scenes on the early-5th century BCBerlin Foundry Cup depict the creation of bronze statuary working, probably by the indirect method of lost-wax casting.[51]
The lost-wax method is well documented in ancient Indian literary sources. TheShilpa Shastras, a text from theGupta Period (c. 320–550 AD), contains detailed information about casting images in metal. The 5th-century ADVishnusamhita, an appendix to theVishnu Purana, refers directly to the modeling of wax for making metal objects in chapter XIV: "if an image is to be made of metal, it must first be made of wax."[15] Chapter 68 of the ancient Sanskrit textMānasāra Silpa details castingidols in wax and is entitledMaduchchhista Vidhānam, or the "lost wax method".[15][16] The 12th century textMānasollāsa, allegedly written by KingSomeshvara III of theWestern Chalukya Empire, also provides detail about lost-wax and other casting processes.[15][16]
In a 16th-century treatise, theUttarabhaga of the Śilparatna written bySrïkumāra, verses 32 to 52 of Chapter 2 ("Linga Lakshanam"), give detailed instructions on making a hollow casting.[15][16]
An early medieval writerTheophilus Presbyter, believed to be theBenedictine monk and metalworkerRoger of Helmarshausen, wrote a treatise in the early-to-mid-12th century[52] that includes original work and copied information from other sources, such as theMappae clavicula and Eraclius,De dolorous et artibus Romanorum.[52] It provides step-by-step procedures for making various articles, some by lost-wax casting: "The Copper Wind Chest and Its Conductor" (Chapter 84); "Tin Cruets" (Chapter 88), and "Casting Bells" (Chapter 85), which call for using "tallow" instead of wax; and "The Cast Censer". In Chapters 86 and 87 Theophilus details how to divide the wax into differingratios before moulding and casting to achieve accurately tuned small musicalbells. The 16th-century Florentine sculptorBenvenuto Cellini may have used Theophilus' writings when he cast his bronzePerseus with the Head of Medusa.[16][53]
The Spanish writer Releigh (1596) in brief account refers toAztec casting.[16]
{{cite encyclopedia}}:ISBN / Date incompatibility (help); See alsoDafas, K. A. (2019). "Greek Large-Scale Bronze Statuary: The Late Archaic and Classical Periods".Bulletin of the Institute of Classical Studies, Monograph (Supplement 138). London: Institute of Classical Studies, School of Advanced Study, University of London.{{cite book}}:ISBN / Date incompatibility (help)
| External videos | |
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 Bronze casting (direct method).Khan Academy (video).Smarthistory. Retrieved6 January 2013. | |
| Adriaen de Vries's bronze casting techniques.J. Paul Getty Museum (video). Retrieved22 January 2013. |
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