A curative blend for a thermosetting polyurethane material that allows for a polyurethane material with greater durability is disclosed herein. The curative blend is composed of 4,4′-methylenebis-(2,6-diethyl)-aniline and a second curing agent selected from the group consisting of N,N′-bis-alkyl-p-phenylenediamine, N,N′-dialkylamino-diphenylmethane with tetrapropoxylated ethylenediamine and an aliphatic diamine. A preferred polyurethane prepolymer is polytetramethylene ether glycol terminated toluene diisocyanate prepolymer. The thermosetting polyurethane is preferably utilized as a cover for a golf ball. The cover is preferably formed over a core and boundary layer.