VARNISH. A varnish is a solution of a resin or of a gum-resin in a liquid, which being spread over a surface, evaporates, and leaves the solid in the form of a brilliant, transparent film. The principal substances used in varnishes and their solvents are the following :— Solvents. Solids. Colours.
Oil of nuts. Amber. Elemi. Gamboge. Annotto.
Oi L of linseed. A nime. Benzoin. Dragon's Red Oil of turpentine. Copal. Colophony. blood. Sanders.
Oil of rosemary. Lac. Mastic. Aloes. Cochineal.
Alcohol. Dammer. Resin. Saffron. Indigo.
Ether. Sandarach. 'Turmeric.
The resins or gums and the solvents may be used either singly or combined. One of the most desirable qualities in a varnish is durability, which depends greatly on the comparative insolubility of the resin employed, its hardness, toughness, and permanence of colour. The art of the varnish maker requires, for its successful prosecution, a considerable amount of chemical knowledge, and the greatest care.
Amber resists the action of ordinary solvents, and requires to be fused at a high temperature. It is hard, and moderately tough, and its colour is scarcely acted on by the air. The objections
to amber are its costliness, and the length of time required for amber varnish to dry. It does not become full hard under many weeks.
Those recognised by British varnishers are classed as cabinet, copal, carriage, wainscot, spirit and turpentine white hard and brown hard varnish. Copal', mastic, and amber varnishes are much employed by the artist and by the photo grapher.
The Sernecarpus anacardium yields a resinous juice, which is known as the blackvarnish of Sylhet. The black varnish of Malabar is from Holigarna longifolia. In China, and Siam, Augia Chinensis yields a varnish; and in Japan, black varnishes are obtained from Rhus vernix, R. succedaneum, and R. verniciferum. In India, a varnish is obtained from the Buchanania latifolia, and another from the Odina wodier. The Martaban varnish is obtained from Melanorrhaaa usitatis sima. Staginaria vernicifolia yields the Japan lacquer. Black varnish of Moulmein is used as first coat before gilding, on lacquered boxes and on pagodas.—Local Committee, .3foulmein.