This section is from the "Henley's Twentieth Century Formulas Recipes Processes" encyclopedia, by Norman W. Henley and others.
Very fine copal varnish for those parts of carriages which require the highest polish, is prepared as follows:
Melt 8 pounds best copal and mix with 20 pounds very clear matured oil. Then boil 4 to 5 hours at moderate heat until it draws threads; now mix with 35 pounds oil of turpentine, strain and keep for use. This varnish dries rather slowly, therefore varnishers generally mix it one-half with another varnish, which is prepared by boiling for 4 hours, 20 pounds clear linseed oil and 8 pounds very pure, white anime rosin, to which is subsequently added 35 pounds oil of turpentine.
Mix the following two varnishes:
(a) Eight pounds copal, 10 pounds linseed oil, 0.5 pound dried sugar of lead, 35 pounds oil of turpentine.
(6) Eight pounds good anime rosin, 10 pounds linseed oil, 0.25 pound zinc vitriol, 35 pounds oil of turpentine. Each of these two sets is boiled separately into varnish and strained, and then both are mixed. This varnish dries in 6 hours in winter, and in 4 hours in summer. For old articles which are to be re-varnished black, it is very suitable.
In order to obtain a limpid rubber varnish, it is essential to have the rubber entirely free from water. This can be obtained by cutting the rubber into thin strips, or better, into shreds as fine as possible, and drying them, at a temperature of from 104° to 122° F., for several days or until they are water free, then proceed as follows:
Dissolve 1 part of the desiccated rubber in 8 parts of petroleum ether (benzine) and add 2 parts of fat copal varnish and stir in. Or, cover 2 parts of dried rubber with 1 part of ether: let stand for several days, or until the rubber has taken up as much of the ether as it will, then liquefy by standing in a vessel of moderately warm water. While still warm, stir in 2 parts of linseed oil, cut with 2 parts of turpentine oil.
This consists of a solution of spirituous gum lac, rosin, and copal, with addition of salicylic acid, etc. Its purpose is mainly the prevention or removal of mold or fungous formation. The salicylic acid contained in the mass acts as an antiseptic during the painting, and destroys all fungi present.
In order to make paint hold on the zinc or tinned copper lining of a bath tub, a wash must be used to produce a film to which oil paint will adhere. First remove all grease, etc., with a solution of soda or ammonia and dry the surface thoroughly; then apply with a wide, soft brush equal parts, by weight, of chloride of copper, nitrate of copper, and sal ammoniac, dissolved in 64 parts, by weight, of water. When dissolved add 1 part, by weight, of commercial muriatic acid. This solution must be kept in glass or earthenware. It will dry in about 12 hours, giving a grayish-black coating to which paint will firmly adhere.
The priming coat should be white lead thinned with turpentine, with only just sufficient linseed oil to bind it. After this is thoroughly dry, apply one or more coats of special bath-tub enamel, or a gloss paint made by mixing coach colors ground in Japan with hard-drying varnish of the 'best quality. Most first-class manufacturers have special grades that will stand hot water.
The following preparation produces a brilliant surface on metals and is very durable, resisting the effect of blows without scaling or chipping off, and being therefore highly suitable for cycles and any other articles exposed to shock:
For the manufacture of 44 gallons, 11 pounds of red copper, 8.8 pounds of yellow copper, 4.4 pounds of hard steel, and 4.4 pounds of soft steel, all in a comminuted condition, are well washed in petroleum or mineral spirit, and are then treated with concentrated sulphuric acid in a lead-lined vessel, with continued stirring for 2 hours. After 12 hours' rest the sulphuric acid is neutralized with Javel extract, and the fine powder left in the vessel is passed through a silk sieve to remove any fragments of metal, then ground along with linseed oil, ivory black, and petroleum, the finely divided mass being afterwards filtered through flannel and incorporated with a mixture of Bombay gum, 22 pounds; Damascus gum, 11 pounds; Judea bitumen, 22 pounds; Norwegian tar rosin, 11 pounds; and 11 pounds of ivory black ground very fine in refined petroleum.' When perfectly homogeneous the mass is again filtered, and is then ready for use. It is laid on with a brush, and then fixed by exposure to a temperature of between 400° and 800° F. The ivory black may be replaced by other coloring matters, according to requirements.