Secret to good surface finish: Nonfouling coolant

But its temperature was unreliable and was causing a build-up of mineral deposits in coolant channels. Part quality was suffering as a result. The Grand Rapids, Mich., firm switched to hot-oil temperature-control systems charged with NF heat-transfer fluid from Paratherm Corp., Conshohocken, Pa. (www.paratherm.com). Scrap rates dropped and production has doubled to about 1,200 finished parts/8-hr shift. Paratherm NF is nonfouling, nontoxic, and rated for service at 650° F.