Abstract: Ingredients or precursor for synthesizing or formulating urethane polymers and prepolymers are dried by admixing therewith an enamine which reacts with the water. While some ingredients, such as polyols and solvents, can be individually dried in this manner, the enamine preferably is added after the polyol(s), solvent(s) and additives have been blended. When prepolymers having a relatively low free isocyanate content are to be synthesized or admixed with other ingredients, a sufficient amount of an isocyanate, preferably the same one used for synthesis, is added to react with amines liberated by the enamine-water reaction to produce an inert urea derivative.