It is not proposed to furnish in this chapter any formulas for the varnishes, driers and japans used by the paint maker or color grinder, but in order to make this work complete, a description of these materials, as they should be, is absolutely necessary. In the first place, a moderate priced Gloss Oil or Rosin and Benzine Liquid is one of the materials required in the manufacture of barrel paints and cheap liquid filler, as well as for the mixing of a paint oil for barn and roof paints. This so-called gloss oil can be made in a power mixer in the cold way by beating up 450 lbs. rosin of medium grade, say F. or G. with 50 gallons 62° benzine, which will yield about 100 gallons liquid. Or if a kettle is handy with a fire place, the rosin may be melted, and while the rosin is still liquid, it may be removed to a safe distance and gradually thinned down with benzine. The heat process produces the best material. Next is required for the manufacture of varnish stain a good mixing varnish of medium color, that will dry to the touch, when mixed with a minimum percentage of oil color, within 8 or at most 10 hours and can be rubbed with the tip of the finger after 48 hours without dusting. A varnish made from hardened rosin, oil and substitute turpentine with addition of China wood oil will fill the bill here and should be moderate in price. Another good mixing varnish for the manufacture of carriage or so-called buggy paints, porch chair enamels, etc., also good white damar varnish and white enamel mixing varnish for white enamels, rubbing varnish for use in coach color grinding, as well as a cheap rubbing varnish for use in machinery paints and fillers is enough of an assortment in the line of varnishes for a moderate sized paint factory. With the present day competition the line of raw materials required, multiplies rapidly enough unless the manager keeps his weather eye open and pays attention to the blending.
Driers constitute quite an important part of the material in stock in a paint factory and while the assortment need not be manifold, attention must be given to the requirements. A pale liquid drier, that does not tend to discolor white or light tints to any extent or make them dry out a decided pink, as is the case with driers in which excessive manganese compounds have been used. But in order to make a small assortment of driers answer, this drier should be well concentrated, so that it can be used in different ways. Next would be a liquid drier, that should contain some hard gum, but may be rather dark in color, for use in machinery paints, etc. Sometimes a manufacturer is called upon to furnish paints to specifications, and it is well to have recourse to two kinds of driers, one a straight oil and solvent proposition without gum, the other an oil, hard gum and solvent proposition, the solvent portion being selected as per specifications.
Grinding Japans, sometimes called coach japan, are a feature of a color grinder's outfit, that requires extra close watching. There are two distinct methods of making these, both kinds having the same oil and drying mediums, litharge and manganese, but one is a hard gum, the other a shellac proposition. The shellac japan, is the one most profitable to the varnish maker, because it does not require long settling, as it is clear and ready for use in less than a week, while the hard gum japan, when made with kauri dust or nubs will require from 4 to 6 weeks to settle clear enough for use. Gold size japan for grinding delicate coach colors is another necessary material for a color grinding establishment.
Liquid driers are best tested for efficiency by mixing 5 parts of it with 95 parts of oil, all by weight, beating the mixture thoroughly, then spread it on a piece of dry glass in thin film and watch it set dust free and also when free of tack. Should set in 12 hours dust free and be hard in 24 hours at the longest. The film must not dry out in wrinkles or tend to creeping or crawling. Varnishes may be applied to glass and body and time of drying noted. Observe appearance of surface, when dry. Apply to bright tin one coat and expose to strong sunlight. A few weeks will give an indication of their wearing properties. Color grinder's japan must dry inside of 30 minutes, when placed in a film on glass and must not show crinkles.