This section is from the book "Spons' Mechanics' Own Book: A Manual For Handicraftsmen And Amateurs", by Edward Spon. Also available from Amazon: Spons' Mechanics' Own Book.
Fuse 8 lb. fine African gum copal; add 2 gal. clarified oil. Boil very slowly for 4 or 5 hours till quite stringy, and mix with 3 1/2 gal. turpentine. This is used for the body part of coaches, and for other objects intended to be polished. The above makes the palest and best copal varnish, possessing great fluidity and pliability, but it is very slow in drying, and, for months, is too soft to polish. Driers are therefore added, but they are injurious. To avoid the use of driers, gum animi is used instead of copal, but it is less durable and becomes darker by age. The copal and animi varnishes are sometimes mixed; 1 pot of the latter to 2 of the former for a moderately quick drying varnish of good quality, and 2 pots of the animi to 1 of the copal for quicker drying varnish of common quality.
Fuse 8 lb. second sorted African copal; add 2 1/2 gal. clarified oil. Boil slowly together for 4 or 5 hours until quite stringy; add 5 1/2 gal. turpentine mixed with 1/4 lb. dried copperas, 1/4 lb. litharge; strain, and pour off. In order to hasten drying, mix with the above while hot 8 lb. second sorted gum animi, 2 1/2 gal. clarified oil, \ lb. dried sugar of lead, \ lb. litharge, 5 1/2 gal. turpentine. This varnish will, if well boiled, dry hard in 4 hours in summer or 6 in winter. Some copal varnish takes, however, 12 hours to dry. This varnish is used for carriages, and also in house painting for the best grained work, as it dries well and has a good gloss. A stronger varnish is made for carriages, known as Best Body Copal Varnish.
8 lb. second sorted gum animi, 2 3/4 gal. fine clarified oil, 5 1/4 gal. turpentine, 1/4 lb. litharge, 1/4 lb. dried sugar of lead, 1/4 lb. dried copperas, boiled and mixed as before. Used for varnishing black japan or dark house painting.
Pour 2 gal. hot clarified oil on 6 lb. very pale transparent amber. Boil till strongly stringy, and mix with 4 gal. turpentine. This will work very well, be very hard, and the most durable of all varnishes, and improves other copal varnishes when mixed with them; but it dries very slowly, and is but little used on account of its expense.
(6) Wainscot varnish is made of 8 lb. gum animi (second quality), 8 gal. clarified oil, 1/4 lb. litharge, 1/2 lb. sugar of lead, 1/4 lb. copperas, boiled together till strongly stringy, and then mixed with 5 1/2 gal. turpentine. It may be darkened by adding a little gold size. This varnish dries in 2 hours in summer, and is used chiefly for house painting and japanning.