This section is from the "Encyclopedia Of Practical Receipts And Processes" book, by William B. Dick. Also available from Amazon: Dick's encyclopedia of practical receipts and processes.
2908. Copal Varnish, according to Professor Boettger should be made by first dissolving 1 part by weight of camphor, in 12 parts ether; when the camphor is dissolved, 4 parts best copal resin, previously reduced to an impalpable powder, are added to the ethereal camphor solution placed in a well-stoppered bottle. As soon as the copal appears to be partly dissolved, and has become swollen, 4 parts strong alcohol, or methylated spirits, and 1/4 part oil of turpentine are added, and, after shaking the mixture and letting it stand for a few hours longer, a thoroughly good copal varnish is obtained.
2909. Common Turpentine Varnish. This is merely clear pale resin dissolved in oil of turpentine; usually 5 pounds resin to 7 pounds of turpentine.
2910. Crystal Varnish. Picked mas-tich, 4 ounces; rectified spirit, 1 pint; animal charcoal, 1 ounce. Digest and filter.
2911. Mastich Picture Varnish. Very pale and picked gum mastich, 5 pounds; glass pounded as small as barley, and well washed and dried, 21/2 pounds; rectified turpentine, 2 gallons; put them into a clean 4 gallon stone or tin bottle, bung down securely, and keep rolling it backwards and forwards pretty smartly on a counter or any other solid place, for at least 4 hours; when, if the gum is all dissolved, the varnish may be decanted, strained through muslin into another bottle, and allowed to settle. It should be kept for 6 or 9 months before use, as it thereby gets both tougher and clearer. Very fine.
2912. Mastich Varnish. Mastich, 8 pounds; turpentine, 4 gallons; dissolve by a gentle heat, and add pale turpentine varnish, 1/2 gallon.
2913. Best Mastich Varnish. Gum mastich, 6 ounces; oil of turpentine 1 quart; dissolve. Mastich varnish is used for pictures, etc.; when good, it is tough, hard, brilliant, and colorless.
2914. Varnish for Paintings. Take mastich, 6 ounces; pure turpentine, 1/2 ounce; camphor, 2 drachms; spirits of turpentine, 19 ounces; add first the camphor to the turpentine ; the mixture is made in a water-bath ; when the solution is effected, add the mastich and the spirits of turpentine near the end of the operation; filter through a cotton cloth.
2915. Tingry's Essence Varnish. Mastich in powder, 12 ounces; pure turpentine, 1 1/2 ounces; camphor, 1/2 ounce; powdered glass, 5 ounces; rectified oil of turpentine, 1 quart.
2916. White Toy Varnish. Tender copal, 71/2 ounces; camphor, 1 ounce; alcohol of 95 per cent., 1 quart; dissolve, then add mastich, 2 ounces; Venice turpentine, 1 ounce; dissolve and strain. Very white, drying, and capable of being polished when hard. Used for toys.
 
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