It may be necessary to premise, that the laborious and scientific process, by which the metallic colours are produced, belongs to the department of the Metallurgist, from whom, the pigments compounded with their fluxes, and ready for use, may be obtained, at a trifling cost, as will be perceived on reference to the Catalogue of Messrs. Knight and Co., of London, from which we have made a selection.
The artist having procured his colours from the metallurgists, selects a fine hair pencil, (the size being in accordance with the style of the ornamentation, large flowers and leaves, such as the Iris, not requiring a small brush) and having carefully arranged his palette, proceeds to paint his design on the porcelain, previously outlining it with a common pencil. In this process the ordinary course of water-colour painting is pursued, and the choice of unbaked biscuit, or fully glazed porcelain, is perfectly arbitrary, there being no difference as regards manipulation, except, perhaps, that on the two former surfaces, objects may require to be retouched.
Of course the metallic colours do not present the same appearance when being used, that they do after having been subjected to the process of firing or baking; and in this respect, the same judgment in the laying on of the colours with regard to their ultimate appearance, will be required as in fresco painting, where the change is effected under other conditions.
Having completed his painting, the artist may pack the porcelain carefully, in order that the ornamented surface (that is, his painting) may not, by touching any other, be effaced, during its conveyance to the pottery where it is to be baked.
Few private amateurs can conveniently bake their own handiwork. As they trusted to the metallurgist for the composition of the colours, so do they generally depend on the potter for the final process. The potteries where the finest porcelain in England, is produced are at Worcester and Stafford; and the manufacturers there, at a trifling cost, will subject amateur painted ware to the heat of their ovens. On the back of any ordinary article of china ware the address of the manufacturer may be found.
Portable ovens are nevertheless sometimes used, and a reference to their construction will be found further on.
A little difficulty attends the gilding of porcelain, and when gold is used, the powder must be mixed with gum water and borax. After being baked, the gold still continues lustreless until burnished with agate or cornelian, as in the ordinary illumination of drawings.
As has been remarked, the gilding process is generally entrusted to professional hands.