The brilliant cucumber or apple-green of Ming times is shown in a pair of exquisite little bowls in the British Museum. Over the green glaze there is a scroll pattern of gold, and on the inside a blue decoration under the glaze. Almost identical with these is the bowl set in a silver-gilt mounting of English make dating from about the year 1540, now preserved in the Gold Room ([Pl. v].). Of a similar but somewhat deeper tint of green are the rare crackle vases, generally of small size, of which there are specimens in the British Museum and in the Salting collection.[90]
Olive and Bronze Glazes.—The monochrome glazes of various shades of olive and bronze are for the most part produced by a soufflé process, in which on a base of one colour a second colour is sprinkled. Thus to form the ‘tea-dust’ a green glaze is blown over a reddish ground derived from iron. The wonderful bronze glazes, of which there are good specimens in the British Museum and in the Salting collection, are produced in a similar way. But some of these (and the same may be said of the ‘iron rusts‘) partake rather of the nature of the more elaborated glazes of the flambé class.
Red and Flambé Glazes ([Pl. xvii].).—We have left the red glazes to the last, both from the complicated nature of the class and because one variety, the sang de bœuf, forms a transition to the ‘splashed’ or flambé division. A red glaze or enamel, we have seen, can be produced from three metals,—from gold, from copper, and from iron. With the Rose d’or, which may be classed as a monochrome enamel, when used to cover the backs of plates and bowls, we are not concerned here—it is not properly a glaze in our sense of the word. The red derived from the sesqui-oxide of iron was only successfully applied as a monochrome when, at a late period, the difficulties attending its use were overcome by combining the pigment with an alkaline flux. This is the Mo-hung or ‘painted red’ of the muffle-stove, which was painted over the already glazed ware, and therefore not properly itself a glaze. In fine specimens it approaches to a vermilion colour; it is the jujube red of the Chinese. It is with this colour, laid upon the elaborately modelled paste, that the carved cinnabar lacquer is so wonderfully imitated.[91]
But it is the red derived from copper that presents the most points of interest. Indeed we now enter upon a series of glazes, beginning with the pure deep red of
PLATE XVII. CHINESE
the sang de bœuf, and then passing over the line to the long series of variegated or ‘transmutation‘[92] glazes that have more than any others fascinated the modern amateurs of ceramic problems. We have already seen how these magic effects are produced by carefully modulating the passage of the oxidising currents through an otherwise smoky and reducing atmosphere in the furnace (([p. page 42]).
The typical sang de bœuf, or the ‘red of the sacrifice,’ as the Chinese call it, was that made under the régime of Lang Ting-tso a forerunner of the three great directors of the imperial manufactory at King-te-chen, and in later times it was always the aim of the potter to imitate his work—the Lang yao—even in trifling details. According to the Père D’Entrecolles, to obtain this red the Chinese made use of a finely granulated copper which they obtained from the silver refiners, and which therefore probably contained silver. Some other very remarkable substances, he tells us, entered into the composition, but of these it is the less necessary to speak, as he confesses that great secrecy was maintained on the subject.
In looking carefully into a glaze of this kind, the deep colouring-matter is seen suspended in a more or less greenish or yellowish transparent matrix, in the form of streaks and clots of a nearly opaque material.[93] The hue, in general effect, varies from a deep blood-red to various shades of orange and brown, but intimately mixed with the red, certain bluish streaks are sometimes to be seen in one part or another of the surface. The colours should stop evenly at the rim and at the base, which parts, if this is achieved, are covered with a transparent glaze of pale greenish or yellowish tint.