A substitute for varnish is produced by adding to 100 parts of casein 10 to 25 parts of a 1 to 10 per cent soap solution and then 20 to 25 parts of slaked lime. The mixture is carefully kneaded until a perfectly homogeneous mass results. Then gradually add 25 to 40 parts of turpentine oil and sufficient water for the mass to assume the consistency of varnish. If it is desired to preserve it for some time a little ammonia is added so that the casein lime does not separate. The surrogate is considerably cheaper than varnish and dries so quickly that paint ground with it may be applied twice in quick succession.

Zapon Varnishes

In the case of many articles which have been colored mechanically or by the battery, particularly with large pieces, an opaque varnish is used as a protection against atmospheric influences. The so-called brassoline, of a brown color, negroline, black, and zapon, which is colorless, are employed, according to the color of the article. The last-named varnish is most commonly used, and gives a fine and durable coating, insoluble in almost all liquids which would come into consideration here, except that it will wash off in soap and water. Zapon varnish is a solution of collodion cotton and camphor in amyl acetate and amyl alcohol, and was formerly used to preserve old manuscripts and legal documents. In the process of zaponizing, the article is slightly warmed and immersed in the varnish, or the latter is applied with a brush. The solution is very durable, and has the advantage that after drying it will not show edges, rings, or spots. Zapon varnish which has become too thick must be diluted, and the brushes must be kept from becoming dry. If it is desired to give an especially warm tone, the article is treated with brushes which have been drawn over beeswax or mineral wax.

For the production of zapon or celluloid varnish, pour 20 parts of acetone over 2 parts of colorless celluloid waste, allowing it to stand for several days in a closed vessel, stirring frequently until the whole has dissolved into a clear, thick mass. Admix 78 parts of amyl acetate and clarify the zapon varnish by allowing it to settle for weeks.