VARNISH is a fluid applied to the surfaces of various articles, as wood, &c., and which, by the evaporation or chemical change of a portion, leaves upon them a shining coating impervious to air and to moisture. Varnishes may be divided into three classes, alcoholic or spirit varnishes, volatile oil varnishes, and fixed oil varnishes.
Spirit varnishes are in general prepared very readily, are easily applied, soon become dry, and emit no disagreeable smell : they are, however, liable to crack or scale ofi; and are incapable of resisting friction or blows. The following are among the most approved spirit varnishes :—Take of mastich 6 ounces, sandarach 3 ounces, reduced to fine powder, and add 4 ounces of coarsely-powdered glass, which prevents the resins from agglomerating into a mass, or sticking to the bottom of the vessel ; digest in a quart of spirit of wine, contained in a loosely-corked vessel for three days in a warm room, shaking the mixture frequently ; then add 3 ounces of incited Venice turpentine to the warm solution, stirring thoroughly till mixed ; let the mixture remain in a warm room for about a week, and then strain it. This is a strong varnish ap plied to chairs and other articles of furniture. Another varnish is formed of copal which has been liquified and afterwards very finely powdered, 3 ounces, mastich 2 ounces, and elemi 1 ounce ; digest in a warm room in a quart of spirit, and when the solution is com plete, add 2 ounces of Venice turpentine. This is a good varnish for violins and other musical instruments. For different purposes the ingredients of spirit varnishes are consi derably varied : seed-lac, benzoin, anime, or frankincense, entering into the composition, according to the use to be made of them.
The only essential or volatile oil largely used in varnishes is oil of turpentine, or, as it is commonly called, spirit of turpentine; and one of the best varnishes into the composition of which it enters is copal varnish. This is
chiefly used for pictures. Another powerful varnish is prepared by adding to highly rectified oil of turpentine about an eighth of its weight of caoutchouc.
In these varnishes the volatile solvents evaporate, but in the case of fixed oil var nishes, the solvent undergoes a chemical change, and dries with the substance dis solved—these are sometimes termed fat var niches. One kind of fixed oil varnish con sists of a mixture of 4 ounces of copal, which has been liquefied and finely powdered, oil of turpentine, and drying linseed oil, each 10 ounces ; digest in a gentle heat till the whole is dissolved; strain it after standing a few days. This forms a solid and nearly colour less glazing, and dries easily at common tem peratures.
The varnish tree of Birma and Japan abounds in every part with a viscid ferrugin ous juice, which quickly becomes black by the contest of the atmosphere. The varnish is collected by inserting pointed joints of bamboo, which are closed at the other end, into wounds made in the trunk and principal boughs. The joints of bamboo are removed after from twenty-four to forty-eight hours, and their contents, which rarely exceed a quarter of an ounce, emptied into a basket made of bamboo and rattan, previously var nished over. In Birma almost every article of household furniture intended to contain either solid or liquid food is lacquered by means of this varnish. It is also much em ployed in the process of gilding: the surface, being first besmeared with this varnish, has then the gold leaf immediately applied to it. The beautiful Pali writing of the Birmese, on ivory, palm-leaves, or metal, is entirely done with this varnish in its native and pure state.