8. Before the oil is used, it is commonly boiled with a small quantity of litharge and red lead, to cause it to dry rapidly, after the paint has been applied. During the boiling, the scum is removed as fast as it rises, and this is mixed with inferior paints of a dark color. Linseed-oil, thus prepared, is vended by dealers in paints, under the name of boiled oil.
9. Spirits of turpentine is produced by distilling with water the resinous juice or sap of several species of the pine. The residuum, after distillation, is the turpentine of commerce. Spirits of turpentine is mixed with paints, to cause them to dry with rapidity. Like oil, it improves with age, and it is sold in the same manner by the common wine measure.
10. White lead, and several other principal paints, are purchased in their crude condition, and reduced to a state of minute division in paint-mills. They are afterwards mixed with boiled oil, and put up in kegs of different sizes for sale. Many articles, however, are pulverized, and sold in a dry state. The preparation of paints is commonly a distinct business, and very few painters seem to be acquainted with the mode in which it is performed.
11. In mixing colors for house and sign painting, white lead forms the basis of all the ingredients. This the color preparer, or the painter himself, modifies and changes by the addition of coloring materials, until it is tinged with the proposed hue. The pigments derived from vegetable bodies, produce, when first applied to surfaces, a brilliant effect; but they cannot long resist the combined influence of air and light, while the mineral colors, in the same exposure, remain unchanged.
12. Painters, in the execution of their work, commonly lay on three coats of paint. In communicating a white, the two first coats are composed of white lead and oil; and in the last, spirits of turpentine is substituted for the oil, for the inside work. For the outside of buildings, especially in warm and dry climates, this liquid is inapplicable, since it causes the paint to crack and flake off. It is, however, frequently used, when the painter is compelled to do his work at too low a rate, or when he is regardless of his reputation.
13. For other colors, the composition for the different coats is the same, except for the two last, in which other coloring substances are added to the materials just mentioned, to give the proposed hue. The tools for painting houses are few in number, and consist chiefly of brushes of different sizes, made of hog's bristles.
14. Graining is understood, among painters, to be the imitation of the different species of scarce woods used for the best articles of furniture. But the manner in which this kind of work is executed can be hardly gathered from a concise description, although it may be easily learned from a practical exhibition of the process by a painter.
15. Ornamental painting embraces the execution of friezes and other decorative parts of architecture on walls and ceilings. The ornaments are drawn in outline with a black-lead pencil, and then painted and shaded, to give the proper effect. Some embellishments of this kind are executed in gold-leaf, in the same manner with gold letters on signs. This kind of work is called gilding in oil.
16. Painting in oil, as applied to the execution of designs, seems to have been invented, or at least to have been brought into notice, in the early part of the fifteenth century, by John Van Eyck, of Flanders. Before this time, house-painting, so far as the exterior was concerned, could have been but little, if at all, practised.
17. One profitable branch of common painting is that of painting and lettering signs. In performing this kind of work, the sign is first covered with two or three uniform coats of paint. The letters are next slightly sketched with chalk or a lead-pencil, and then formed in colors with a camels'-hair brush. When the letters are to be gilt, the process, so far, is precisely the same. The leaf is laid upon the letters, while the paint is in a tenacious state, and is suffered to remain untouched, until the oil has become dry, after which the superfluous gold is removed. The whole is then covered with an oil varnish, which, in plain lettering, completes the operation.