This section is from the book "The Tinman's Manual And Builder's And Mechanic's Handbook", by Isaac Ridler Butt. Also available from Amazon: The Tinman's Manual And Builder's And Mechanic's Handbook.
1. Amber one pound, pale boiled oil ten ounces, turpentine one pint. Render the amber, placed in an iron pot, semiliquid by heat; then add the oil, mix, remove it from the fire, and when cooled a a little, stir in the turpentine. 2. To the amber, melted as above, add two ounces of shellac, and proceed as before.
This varnish is rather dark, but remarkably tough. The first form is the best. It is used for the same purposes as copal varnish, and forms an excellent article for covering wood, or any other substance not of a white or very pale color. It dries well, and is very hard and durable.
Amber one pound, boiled oil one-half pint, powdered asphaltum six ounces, oil of turpentine one pint. Melt the amber, as before described, then add the asphaltum, previously mixed with the cold oil, and afterwards heated very hot, mix well, remove the vessel from the fire, and when cooled a little add the turpentine, also made warm.
Each of the above varnishes should be reduced to a proper consistence with more turpentine if required. The last form produces the beautiful black varnish used by the coachmakers. Some manufacturers omit the whole or part of the asphaltum, and use the same quantity of clear black rosin instead, in which case the color is brought up by lampblack reduced to an impalpable powder, or previously ground very fine with a little boiled oil. The varnish made in this way, lacks, however, that richness, brilliancy, and depth of blackness imparted by asphaltum.
1. (Pale.) Amber pale and transparent six pounds, fuse, add hot clarified linseed oil two gallons, boil till it strings strongly, cool a little, and add oil of turpentine four gallons. Pale as copal varnish; soon becomes very hard, and is the most durable of oil varnishes; but requires time before it is fit for polishing. When wanted to dry and harden quicker, "drying" oil may be substituted for linseed, or "driers" may be added during the boiling. 2. Amber one pound; melt, add Scio turpentine one-half pound, transparent white resin two ounces, hot linseed oil one pint, and afterwards oil of turpentine as much as sufficient; as above. Very tough. 3. (Hard.) Melted amber four ounces, hot boiled oil one quart; as before. 4. (Pale.) Very pale and transparent amber four ounces, clarified linseed oil and oil of turpentine, of each one pint; as before.
Amber varnish is suited for all purposes, where a very hard and durable oil varnish is required. The paler kind is superior to copal varnish, and is often mixed with the latter to increase its hardness and durability.