A curative blend for a thermosetting polyurethane material that allows for a polyurethane material with greater durability is disclosed herein. The curative blend is preferably composed of N,N″-dialkylamino-diphenyl-methane in an amount of 25 to 75 parts per one hundred parts of the curative blend and 4,4″-methylenebis-(2,6-diethyl)-aniline in an amount of 25 to 75 parts per one hundred parts of the curative blend. 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.