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Another (Oz of melted copal pour or oz)
On 16 oz. of melted copal, pour 4, 6, or 8 oz. of linseed-oil boiled, and quite free from grease. When well mixed by repeated stirrings, and after they are pretty cool, pour in 16 oz. of the essence of Venice turpentine. Pass the varnish through a cloth. Amber varnish is made the same way.
To make Black Copal Varnish.
Lampblack, made of burnt vine-twigs, or black of peach-stones. The lampblack must be carefully washed and afterwards dried. Washing carries off a great many of its impurities.
To make Yellow Copal Varnish.
Yellow oxide of lead, of Naples and Montpellier, both reduced to impalpable powder. These yellows are hurt by the contact of iron and steel; in mixing them up, therefore, a horn spatula with a glass mortar and pestle must be employed.
Gum guttæ, yellow ochre, or Dutch pink, according to the nature and tone of the color to be imitated.
To make Blue Copal Varnish.
Indigo, prussiate of iron (Prussian blue), blue verditer, and ultramarine. All these substances must be very much divided.
To make Green Copal Varnish.
Verdigris, crystallized verdigris, compound green (a mixture of yellow and blue). The first two require a mixture of white in proper proportions, from a fourth to two-thirds, according to the tint intended to be given. The white used for this purpose is ceruse, or the white oxide of lead, or Spanish white, which is less solid, or white of Moudon.
To make Red Copal Varnish.
Red sulphuretted oxide of mercury (cinnabar vermilion), red oxide of lead (minium), different red ochres, or Prussian reds, etc.
To make Purple Copal Varnish.
Cochineal, carmine, and carminated lakes, with ceruse and boiled oil.
Dragon's blood.
Brick Red.
Chamois Color.