This invention relates to a process for coating a substrate comprising contacting the substrate with a low volatile organics, moisture curable, two-component coating composition comprising an admixture of an A-side and a B-side, said A-side comprising an aliphatic polyisocyanate having an isocyanate index relative to the number of isocyanate-reactive groups in said coating composition of at least about 200, preferably at least about 300, more preferably at least about 500, said B-side comprising a tertiary amine catalyst and optionally an isocyanate-reactive compound selected from the group consisting of monoahls, polyols, imines, oxazolidines, and combinations thereof, said coating composition optionally containing a solvent in an amount of less than about 45%, based upon the weight of the polyisocyanate in said coating composition, said coating composition having a viscosity as measured by ZAHN cup 2 of less than about 200 seconds, said composition being essentially free of any volatile mono- and di-isocyanates, and said composition being moisture curable upon exposure to atmospheric moisture. Also claimed is the coating composition itself.