For a dark steel color, that is to be simply used on iron or steel, either for dipping or for application with the brush, after thinning with benzine or turpentine substitute, the inert material must be buoyant in order to keep in suspension and prices being rather low, the pigment must be selected so as not to require too much of the more expensive vehicle.
6 lbs. lithopone, 4 lbs. dry lampblack, 68 lbs. American Paris white, 10 lbs. raw linseed oil and 14 lbs. brown japan of the grade described in the following formula. (Figuring on a total of 102 lbs. of material allows for waste and evaporation in the process of manipulation.)
Fuse by melting 100 pounds F rosin, 6 gallons raw linseed oil, 15 pounds litharge and 15 pounds fine black oxide of manganese, cut with 7 gallons substitute turpentine and finally thin with 60 gallons of 56° benzine. Result 60 gallons.
Make as above, but use 100 pounds F rosin, 20 pounds brown sugar of lead, 10 gallons raw linseed oil, 30 pounds fine black oxide of manganese, cut out with 5 gallons of 90% coal tar benzol and thin finally with 45 gallons of 56° benzine. Result 65 to 67 gallons. This is an excellent drier for moderate priced ready mixed paints containing mineral pigments.
Melt 110 pounds hardened rosin and fuse with 9 gallons varnish maker's linseed oil and 44 pounds litharge. Thin with 50 gallons turpentine. Result 67 gallons.
A reliable japan for use in grinding coach colors, etc., can be made by fusing 55 pounds brown No. 3 kauri gum with 17 gallons V. M. linseed oil, 100 pounds litharge and 20 pounds fine black manganese oxide, until the drying mediums are well amalgamated, when 55 gallons of turpentine is added in the thinning room. The result, when settled clear, will be 72 gallons, weighing 8 1/2 pounds each. This japan dries not merely on top of the film, but right through, and the only drawback is, that it requires settling in a warm storage room for over a month, before it becomes clear enough for use. This is not the case with grinding japans made with gum shellac.