One of the earliest applications for metallic stearates was the addition of Zinc Stearate to rubber compositions as a mold release agent. It is a minor application in today’s market because, like grease makers, rubber manufacturers have learned to put separate raw materials into their mix - in this case, ZnO and “rubber-grade” stearic acid. The external application of Zinc Stearate to molded rubber slabs and parts, however, is still common practice. Whether dusted on or applied as slurry in a dip tank, stearate on the exterior is an excellent anti-block. Zinc is favored for its solubility in the cured rubber and its outstanding lubricity. Finer particle sizes are naturally preferred to maximize covering.