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Home › Adhesives, Paints, and Varnishes › Adhesives, Paints, and Varnishes: Copal
Adhesives, Paints, and Varnishes: Copal
Copal Varnishes. - Copal dissolved in alcohol forms a hard, durable varnish for fine cabinetwork and similar purposes, but it is more expensive than shellac and no better for ordinary purposes. To prepare ordinary copal varnish, first melt the resin with gentle heat in a double boiler. Then pulverize and mix it with sand. Finally dissolve it in strong alcohol and strain and filter. The addition of elemi resin or solution of turpentine softens it.
To make a transparent copal varnish, put 6 ounces of melted and pulverized copal and 6 ounces of 95 per cent alcohol in a glass bottle or fruit jar, cork it tightly, and set in a warm place until dissolved. Then add 4 ADHESIVES, PAINTS, AND VARNISHES ounces of turpentine and 1 ounce of brittle; hence they are liable to crack ether.
Or dissolve 1 ounce of camphor in 1 quart of alcohol. Put this in a glass bottle or fruit jar with 4 ounces of melted and pulverized copal, and set in a warm place until dissolved.
Strain, filter, and dry the sediment, if any, for future use.
Or dissolve 7 ounces of copal, 1 ounce of mastic, and ounce of Venetian turpentine in 11 ounces of alcohol. First dissolve the copal in a small amount of alcohol with ounce of camphor. Add the mastic and turpentine and thin with the remainder of the alcohol. This is a good varnish for articles frequently handled.
Colored Copal Varnish. - - On account of its superior hardness, copal varnish is frequently used as a vehicle for various coloring matters for toys, picture frames, bric-a-brac, articles of furniture, and the like. Experiments may be made with any desired colors, but the following suggestions may be helpful:
For flaxen gray, mix ceruse with an equal quantity of English red or carminated lake. Add a little Prussian blue.
For yellow, use yellow oxide of lead or Naples or Montpellier. Mix in a glass vessel, and do not let it come in contact with iron or steel. Or use gummigutta, yellow ocher, or Dutch pink.
For violet, vermilion, blue, and white.
For purple, cochineal, carmine, and carminated lakes with ceruse. Or Prussian blue and vermilion.
For green, a mixture of verdigris with ceruse, white lead, or Spanish white. Or a mixture of yellow and blue.
For red, red oxide of lead, cinnabar, vermilion, red ocher, or Prussian red. These coloring matters may be used ground with boiled oil or in the form of powders, water colors, or aniline dyes.