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.
Moist Oil-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.
Moist Water-Colors. Require no grinding, simply dilution, but it must be remembered water-colors cannot be used where the outlines are made with lithographic crayons,
Fig. 13. Stucco Wall Paint Brush.
for these being greasy would grease the brush, and the water-color instead of laying flat, would ridge and spot.
Firing. 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
