An organic peroxide formulation includes at least one organic peroxide and at least one cellulose compound. Embodiments of the organic peroxide formulations significant improvements in surface tackiness (often including but not limited to tack-free surfaces) when curing elastomers in the presence of oxygen. Embodiments of the present invention relate to organic peroxide formulations that can cure solid elastomers in the full or partial presence of oxygen using, for example, a hot air oven or tunnel, molten salt bath, or steam autoclave. Embodiments of the invention also relate to crosslinkable elastomer compositions, processes for curing the elastomers, and products made by such processes.