that his paint contained an inadequate amount of pigment. Given a perfect binder, the paint problem would be simple and the only function of pigment would be to color and obscure the surface; then the hypothesis under which we are working would fall. Until, however, a binder is obtained that will dry fast enough, that when dry is impervious to moisture and gases, and that will not wear out, pigment will be necessary to shield and to protect the dried oil from the agencies that destroy it, the chief of which are rainwater and sunshine.

A pigment that will not hold the oil produces a fugitive paint. Any pigment that will take and retain oil or binding material, and that is not changed by the agencies that destroy dried oil, or the binder, will make a durable paint for structural steel provided it is fairly treated and properly