This is for use in surfacing castings. Should be used as a priming coat, made thin with benzine and applied with the brush. Then when dry, should be gone over with the paste filler, using wide flexible spatulas, wetting the paste slightly with benzine in order to smooth it down. When dry it is sandpapered and when gone over with some turpentine or benzine, must not show cracking or parting on drying. In order to obtain best results, the japan in which the pigments are ground for this filler, should consist of the following ingredients: -
95 lbs. kauri brown chips, 15 lbs. hardened rosin, 35 gallons raw linseed oil, 60 lbs. litharge, 10 lbs. fine black oxide of manganese, fused as usual in making japan, until a clear plaster is had, when tested on glass. Take to thinning room and cut out first with 10 gallons turpentine or turpentine substitute and reduce with 50 gallons 62° benzine. Should result in 100 gallons of brown japan. To produce 100 lbs. of filler, place in a chaser or strong mixer 3 gallons of this japan with 64 lbs. mineral black filler and 16 lbs. Paris white.