aximum water and Weather resistance is obtained by using a paint containing gilsonite and the gas-proofed tung or oiticica (or mixtures of the two) oil without the addition of any other drying oil, but it is found that while this combination is commercially usable, it is difficult to brush, and it is preferred to add a viscosity reducing drying oil. For this purpose it is found that perilla oil is particularly satisfactory.

Other drying oils such as linseed, soya bean, sunflower seed, hempseed, menhaden, or sardine oil may be used instead of the perilla oil. The perilla oil, however, has considerably better drying properties than the other oils mentioned.

Gilsonite, when fluxed with raw tung or oiticica oil, gives an unstable liquid, that is, one which will take on excessive body when aging, and one which is not gas-proof.