Copal is a brittle aromatic resin used in varnishes.
¶ Copal varnish is made of gum copal, spirits of turpentine, and linseed oil; gum copal is found in the deserts of Africa: the best is from Zanzibar. It is found by the natives in the sand, and naturalists differ about its origin, some saying that it exudes contiunally from the earth through the sand and becomes hard by exposure, others saying that it is a vegetable deposit of the nature of other gums, and that the trees which have produced it have disappeared, and the gum now found was formed centuries ago.
¶ It is a curious natural phenomenon, despite such explanations. It is the hardest gum known, and cannot be cut or dissolved with either alcohol or turpentine, but must be reduced to a fluid state hy melting. The gum is put in large kettles over a slow fire, and, when melted, turpentine and linseed oil are added. When this varnish is put on furniture, the turpentine and the volatile part of the oil evaporate and leave a solid deposit of pure gum, and one which will resist the action of the atmosphere and to a great extent will resist water.
¶ Imitations of copal varnish are made of rosin instead of gum copal, and are used only on cheap cabinetware, and by those who manufacture wholesale, as the difference in price is of importance in finishing cheap goods, the common article being worth from 75 cents to $1.50 per gallon, while the best copal brings from $2.50 to $3.50 per gallon. Spirits varnish is a quick drying but not a durable varnish, and is used for small surfaces, such as cane seat chairs; it is made of gum shellac dissolved in spirits of xvine. Gum sandrac is also used in this way. European cabinet-makers do not use copal varnish on furniture; they use little of any kind of varnish, only enough to finish up fine carving when they cannot reach in the crevices to polish.
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