The malleability of gold

Nutting, Jack; Nuttall, J.

doi:10.1007/bf03216517

Cited by 24 publications

(18 citation statements)

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“…The higher atomic numbered metals are larger and also heavier. Gold is a heavy metal with a density of 19.3 g/cm-' whereas silver has a density of 10.5 g/cm 3 and copper a density of 8.93 g/cm', Thus, in describing alloys we must differentiate compositions given in terms of weight per cent -the relative weights of alloying metals per centand compositions given in terms of atomic per cent, ie how many atoms there are of each metal in the alloy. This is illustrated by gold-copper alloys.…”

Section: Basic Mechanisms Of Hardeningmentioning

confidence: 99%

“…Gold containing high silver of 25% or more was known as 'electrum' and was a pale lemon yellow colour. As we know, pure metals tend to be soft and ductile and gold is the ultimate example, being very soft and the most malleable (ductile) of all pure metals (3). In the modem production of gold jewellery, this softness is of little advantage in jewellery manufacture (4) and a disadvantage in service when items are liable to distort, fracture and scratch and wear heavily during use.…”

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confidence: 99%

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Metallurgy of Microalloyed 24 Carat Golds

Corti

1999

Gold Bull

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Pure gold is relatively soft with a low yield point and this has several drawbacks in the fabrication of 24 ct gold jewellery, limiting design possibilities as well as making such jewellery prone to scratching and wear. In recent years, however, there have been a number of hardened 24 ct materials developed with finenesses of 99.5 -99.9%, some already in commercial production, where improved hardness and strength have been achieved by microalloying. This paper examines their metallurgy -the theoretical basis for hardening and some candidate alloying elements which could form the basis of microalloyed 24 ct golds. These are compared to known published information on the compositions and properties of actual microalloyed 24 ct golds. The scope for adapting the microalloying approach to 22 ct and other carat golds is also discussed.

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Section: Basic Mechanisms Of Hardeningmentioning

confidence: 99%

mentioning

confidence: 99%

Metallurgy of Microalloyed 24 Carat Golds

Corti

1999

Gold Bull

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“…To alter gold from a solid metal into a fluid ink to use it for chrysography required milling it into a powder that can be tempered with appropriate medium. Because of its malleability gold could be beaten to leaves of only 50-100 nm thickness but for the very same reason turning it into a fine powder was an arduous task requiring a special mill as described by Theophilus [5,25]. Le Begue, on the other hand, suggests apothecary mill rather than grinding on porphyry, or to add other substances such as salt or honey to prevent gold particles from re-adhering [1].…”

Section: Mosaic Gold and Porporinamentioning

confidence: 99%

“…Forming amalgams with base metals (tin was the most common, but is not the only one) had its very practical purpose as it promotes a more immediate bonding with sulfur. However mercury was also used to separate gold from its impurities, or if it was not sublimated, to render gold more brittle and therefore easier to grind if fine particles were sought [25].…”

Section: Mosaic Gold and Porporinamentioning

confidence: 99%

Gold and not so real gold in Medieval treatises

Bogovic-Zeskoski¹

2015

Cons. Património

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The aim of this study is to evidence diverse materials and processes used by artisans (and alchemists) required to synthesize a visually viable replacement for gold. The emphasis of the research is upon the production of mosaic gold or porporina, a pigment that has survived into modern times, which was used as ink and as paint. Base metals, mostly tin, but also alloys were used both into foils coated with glazes and varnishes and as pigment. The research focuses upon recipes documented in treatises dating from Antiquity to the late Medieval period (ca. 1500) and an attempt is made to answer two questions. In the first place, why was there a need for a surrogate? Secondly, why are there so few tangible examples detected on surviving artifacts? In conclusion, an argument is offered pointing out that, although much can be learned by scientific examination of artifacts, textual analysis is equally important and necessary to unravel mysteries of ancient technologies. KeywordsMosaic gold Glaze Porporina Chrysography Amalgam Medieval treatises Ouro e imitações de ouro nos tratados medievaisResumo O objectivo deste estudo é mostrar os diversos materiais e processos usados pelos artesãos (e alquimistas) na procura de um adequado substituto do ouro. A pesquisa é direccionada especialmente para a produção de ouro-músico ou purpurina, um pigmento que se manteve até à actualidade e que foi usado sobretudo como tinta e como pigmento. Metais comuns, particularmente estanho, assim como ligas, foram usados quer como folhas sobre as quais eram aplicadas velaturas e vernizes, quer como pigmento. A pesquisa incide sobre as receitas registadas nos tratados da Antiguidade até ao período medieval (ca. 1500) e é feita uma tentativa de responder a duas questões. Em primeiro lugar, a que se deveu a necessidade de uma imitação do ouro? Depois, por que é que sobreviveram tão poucos exemplos? Em conclusão, é referido que, ainda que muito se possa aprender através da análise científica das obras, a análise documental é igualmente importante e necessária para se esclarecer os mistérios das antigas tecnologias.

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“…It can be rolled and hamlnered to foil 50-100 nm in thickness, which corresponds to 99·9996% reduction in thickness or an equivalent logarithmic strain of 10 (Ref. 15). This compares with the logarithmic strain of 7 that can be achieved in the production of copper wires without intermediate annealing.…”

Section: Gold Leafmentioning

confidence: 99%

The Metallurgy of Gold

Grimwade

1992

Interdisciplinary Science Reviews

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The discovery of gold about 7000 years ago together with that of its sister metals from group IB of the periodic table can be said to have laid the early foundations of metallurgy as a science and a technology. The attraction of the metal to man derives from its relative scarcity and high value, its excellent corrosion resistance, its unique yellow colour and the fact that it is one of the most malleable of all metals. The metallurgy of gold is discussed with reference to its physical and mechanical properties, its fabrication and alloying behaviour and electrodeposition processes. Those properties which are particularly relevant to the use of gold in various applications are highlighted. The reasons for the yellow colour and the effect of alloying on colour are given. The malleability of gold allows it to be hammered to extreme thinness and the production of gold leaf is described. Solid solution and compound formation in alloys of gold are considered in terms of the alloying theory of Hume-Rothery, Raynor and their coworkers, and particular mention is made of gold-mercury amalgams and their use in the 'fire gilding' process for producing gold coatings on other metal substrates. This process was rendered obsolete by the development of electroplating. The principles and practice of gold electroplating and electroforming are discussed.

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The malleability of gold

Cited by 24 publications

References 0 publications

Metallurgy of Microalloyed 24 Carat Golds

Metallurgy of Microalloyed 24 Carat Golds

Gold and not so real gold in Medieval treatises

The Metallurgy of Gold

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