The Manufacturer and Builder 9, 1875
The coarse wood is first coated with a colored size, which is prepared by thoroughly mixing lip in a a warm solution of 1 part of commercial glue to 6 parts of water, a sufficient quantity of the commercial mahogany brown, which is in reality an iron oxid. This is best effected by adding in excess a sufficient quantity of the dry color with the warm solution of glue, and thoroughly mixing the mass by means of a brush until a uniform paste is obtained, in which no more dry red particles are seen.
A trial coat is then laid upon a piece of wool. If it is desired to give a light mahogany color to the object, it is only necessary to add less, and for a darker color more, of the brown body color. When the coat is dry, it may be tested, by rubbing with the fingers, whetherr the color easily separates or not. In the former case, more glue must be added until the dry trial coat no longer perceptibly rubs off with the hands. Having ascertained in this way the right condition of the size color with respect to tint and strength, it is then warmed slightly, and worked through a hair sieve by means of a brush. After this it is rubbed upon the wood surface with the brush, which has been carefully washed. It is not necessary to keep the color warm during the painting. Should it become thick by gelatinizing, it may be laid on the wool with the brush and dries more rapidly than when the color is too thin. If the wool is porous and absorbs much color, a second coat may be laid on the first when dry, which will he sufficient in all cases. On drying, the size color appears dull and unsightly, but following coat changes immediately the appearance of the surface. This coat is spirit varnish. For its production 3 parts of spirits of wine of 90° are added in excess to 1 part of red acaroid resin in one vessel, soil in another 10 parts of shellac, with 40 parts of spirits of wine of 80°. By repeated agitation for three or four days, the spirit dissolves the resin completely. The shellac solution is then poured carefully from the sediment, or better still, filtered through a fine cloth, when it may observed that a slight milky turbidity is no detriment to its use. The resin solution is best filtered into the shellac solution by pouring through a funnel loosely packed with wadding.
When filtered, the solutions of both resins are mixed by agitating the vessel, and letting the varnish stand it few days. The acaroid resin colors the shellac, and imparts to it at the same time the degree of suppleness usually obtained by the addition of Venetian turpentine or linseed oil. If the varnish is to be employed as a coat, the upper layers are poured off at once front the vessel. Ono or two coats suffice, an it rule, to give the object an exceedingly pleasing effect. The coats dry very quickly. are intlet, token not to apply the second coats till the first is completely dry.
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