Varnish, Copal. Prep. 1. (Oil.)—a. From pale hard copal, 2 lbs.; fuse, add of hot drying oil, 1 pint; boil as before directed, and thin with oil of turpentine, 3 pints, or q. s. Dries hard in 12 to 24 hours.
b. From clear and pale African copal, 8 lbs.; pale drying oil, 2 galls.; rectified oil of turpentine, 3 galls.; proceed as before and immediately strain it into the store can or cistern. Very fine, hard, and durable.
2. (Spirit.)—a. From coarsely powdered copal and glass, of each 4 oz.; alcohol of 90% (64 o. p.), 1 pint; camphor, 1⁄2 oz.; heat the mixture, with frequent stirring, in a water bath, so that the bubbles may be counted as they rise until solution is complete, and, when cold, decant the clear portion.
b. From copal (which has been melted, dropped into water, and then dried and powdered), 4 oz.; gum sandarach, 6 oz.; mastic, 2 oz.; pure Chio turpentine, 3 oz.; powdered glass, 5 oz.; spirit of 90%, 1 quart; dissolve by a gentle heat. Dries rapidly.
3. (Turpentine.) To oil of turpentine, 1 pint, heated in a water bath, add in small portions at a time, of powdered copal (prepared as above), 3 to 4 oz.; dissolve, &c., as before. Dries slowly, but is very pale and durable.
4. (Japanner’s copal varnish.) From pale African copal, 7 lbs.; pale drying oil, 1⁄2 gall.; oil of turpentine, 3 galls.; proceed as in No. 1. Dries in 20 to 60 minutes, and may be polished as soon as hard, particularly if stoved. See Japanning.
Obs. All copal varnishes, when properly made, are very hard and durable, though less so than those of amber; but they have the advantage over the latter of being paler. They are applied on coaches, pictures, polished metal, wood, and other objects requiring a good durable varnish. Animé is frequently substituted for copal in the copal varnishes of the shops. See Varnishes, Body, Carriage, and Copal, &c.
Varnish, Crystal. Prep. 1. From genuine pale Canada balsam and rectified oil of turpentine, equal parts. Used for maps, prints, drawings, and other articles of paper, and also to prepare tracing paper, and to transfer engravings.
2. Mastic, 3 oz.; rectified spirit, 1 pint; dissolve. Used to fix pencil drawings.
Varnish, Drying. Spirit copal varnish.