The internal lubricant is most commonly 0.6-0.8 phr of calcium stearate, with external lubrication being provided by 1.0-1.2 phr of paraffin wax and 0.1-0.15 phr of oxidized polyethylene wax. The balance of these ingredients is essential for long, uninterrupted runs at high output. They may be added in combination form as a one-pack at about a 2.0-phr level at more or less similar material cost. Tin mercaptoethyl oleates can be replaced in this application with antimony mercaptoacetate. Equivalent processing usually requires slight revision of the internal-external lubricant balance.