It has been reported elsewhere that primary amines produce imines on reaction with aldehydes and ketones, although ketones react more slowly than aldehydes, sometimes requiring higher temperatures and longer reaction times.51,52 In addition, the progression of the reaction is inhibited by the formation of water, and the literature identifies that, in reaction studies, the water must be removed either by distillation or with a drying agent.51 This latter behavior is of particular interest in the case of the waterborne latex. It would seem reasonable to propose then that the presence of water will ‘‘block’’ the crosslinking reaction until after sufficient drying has occurred. The water content of the film reaches a critical level where the equilibrium of the keto-hydrazide is shifted in favor of crosslinking.