Page 82 - The colours of each piece: production and consumption of Chinese enamelled porcelain, c.1728-c.1780

CHAPTER 2 The Production of Enamelled Porcelain and Knowledge Transfer

structure. A wide range of colours can be produced in enamels by

incorporating certain elements, mostly transition metals.

The most important are the elements of…titanium, vanadium,

chromium, manganese, iron, cobalt, nickel and copper…enamels

containing these elements become coloured immediately after centration

of colourant.

The colour created by the transition elements depends on several

factors, including the composition of enamel, the presence of oxidizing or

reducing agents, the concentration of the colorant the melting condition

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etc.

The pigments of metallic materials which have undergone oxidation will need to

be added to the enameled glass. Only when these pigments have been added do we

get coloured enamels. When enamels are melted together, they produce an almost

clear glass with a slightly bluish or greenish tinge, known as a flux. This clear flux

forms the basis from which coloured enamels are made by introducing, as a colouring

agent, metallic oxides when the flux is in a molten state. The inclusion of 2 or 3 percent

of one of these oxides is generally sufficient to produce a useful colour. The heated

enamel after being thoroughly stirred is usually poured out onto a slab and allowed to

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solidify into cakes of approximately 4 to 5 inches (10 to 13 centimetres).

27 Woodrow Carpenter, ‘Enamel Photography’, Glass on Metal, 4(1985), pp.46-50.
28 According to the Imperial Workshop Archives, enamel colour was also recorded as pieces;
however, the size was not mentioned. For example, in year 1729, the emperor ordered the Imperial
Workshop to make colours on the back. See, Zhu Jiajin, Yangxindian zaobanchu shiliao jilan,
diyiji [The Archival Resource of Imperial Workshops of Yongzheng reign] (Beijing: The
Forbidden City Publication. 2003), p.178.
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