Abstract: A composition is disclosed for producing an elastomer using toluene diisocyanate prepolymers. The composition is prepared by mixing (a) polyisocyanate, (b) curative component and (c) a catalyst consisting essentially of 1,8-diazabicyclo(5,4,0) undec-7-ene; wherein the polyisocyanate comprises at least 70 percent by weight of the isocyanate containing composition is a toluene diisocyanate terminated prepolymer containing less than about 2 percent by weight free toluene diisocyanate monomer and the curative component contains compounds having isocyanate-reactive groups, wherein at least 40 percent by weight of the compounds having isocyanate-reactive groups are compounds having at least one hydroxyl group.