The use of metallic pigments in the preparation of protective paints

An examination of the more available metallic pigments has been made with the object of preparing paints capable of protecting steel cathodically; for this to occur two conditions must be fulfilled: The metallic pigment must be of a metal less noble than iron. The pigment particles must be in metallic contact with each other and with the coated steel. It has been shown that whereas aluminium powder, zinc dust, and magnesium powder satisfy condition (i), only zinc dust fulfils condition (ii).