The colors used in painting upon china or earthenware are, for the most part, oxides of certain metals. A few colors, however, such as the deep transparent blues, and yellows from one source, are really, to a certain extent, stained glass, the glass having more or less completely dissolved the coloring matter. China or enamel colors then, from their containing, as an essential constituent, a glass or flux of vitrifiable composition, are called vitrifiable pigments.
The following list of colors in dry powder will serve all purposes:
Blue. Azure. Old Tile.
Turquoise Outremer. Schwartzenburgh.
Green. Celadon. Deep. Dover. Emerald. Gordon. Rose-leaf. Sevres.
Purple. Ordinary. Royal. Ruby d'Or.
Red. Flesh. Ordinary. Salmon. Scarlet.
White. Hard. Medium. Soft.
Moist Oil-Colors. These, as well as moist water-colors prepared expressly for this kind of painting, can be purchased at any large paint dealer's store.
Having all the general requisites at hand we are ready to begin work. Before, however, we bring out the brushes and mix the colors, we must decide where the color is to go when it is mixed. The first concern is the design, and this whether we intend to have a background or not. Therefore, the first operations will be directed toward producing the outline.
According to the method which may be adopted for sketching the outline, there will be required a black lead pencil, HB or B, lithographic crayon, a tracing point, tracing paper, transfer paper, a pounce, Indian ink, rose pink, or lamp black, and gummed paper or modelling wax.
Lithographic crayon may be made by mixing 32 parts bees-wax, 4 parts purified tallow, 24 parts soap, 1 part nitrate of potassium, dissolved in 8 parts water, 6 parts lamp black.
The surface of the china having been thoroughly cleaned by washing and dried, the design may be marked on by either of the following plans: By marking with lithographic crayon, black lead pencil, pricked stencil pattern and pounce-bag, copying or transfer paper. The design being drawn on the ware proceed to mix the color with the mediums. Different pigments require different proportions of medium, and the same pigment requires varying proportions, according to the end sought. It may be said generally that the ordinary blues, rose, and purple take most fat and the yellows the least. More fat, again, is required when it is desired to lay color flat, as in backgrounds, either with the brush, or when the use of the dabber is contemplated, or to have the color flow to a very slight extent as in delicate shading, or to lay a very thin tint.
In mixing powder color, the orthodox direction is to lay a little powder on the slab, and add to it just so much oil as will make it into a thick paste, to be subsequently reduced to the requisite thinness by spirit. The grinding is done on the slab with the muller, and when ground to a thick cream consistency it is called prepared color.
Those who adopt moist oil-color in tubes will find that the color when fresh contains exactly the right quantity of oil. The color only requires thinning to be fit for use.
Require no grinding, simply dilution, but it must be remembered water-colors cannot be used where the outlines are made with lithographic crayons, for these being greasy would grease the brush, and the water-color instead of laying flat, would ridge and spot.
The ware being painted the next step is to make the work imperishable by fire; this part of the process need not be done by the painter, for the maintenance to a nicety of different definite degrees of heat in furnaces of special adaptation are not to be found united except in factories devoted to the business. If the painting has gone to the kiln with too much oil in it, it is certain that the color will blister. If it comes back with a dry powdery look, with the color scarcely adhering, it shows that the color was over-diluted with turpentine.