Abstract: A method of treating cleaning solvent used to clean mechanical parts. The method includes adding to the cleaning solvent a treating composition selected from the group of C.sub.5 -C.sub.14 alcohols, C.sub.2 -C.sub.8 dials, C.sub.10 -C.sub.14 polyols, and C.sub.4 -C.sub.14 glycol ethers, and mixtures thereof. A further embodiment includes the foregoing plus adding a clarifying agent from the group of aromatic, aliphatic and alkaryl sulfonic acids and sulfonic acid salts, esterified polyols, and alkyl phenol formaldehyde resins capped with alkoxy groups. The solvent is vaporized and condensed to effect recycling thereof without adding substituted quantities of treating composition to the solvent.

Abstract: A treated solvent composition for washing mechanical parts or the like. The solvent contains not more than about 25% aromatic solvents with the balance being aliphatic and other non-aromatic solvents having a flashpoint of at least 100.degree. F. The solvent is treated with up to 10 parts of an additive composition selected from the group consisting of C.sub.14 and lower alcohols, diols, polyols, lower glycols, and lower glycol ethers and mixtures thereof. In use, finely dispersed contaminant particles settle from the body of the solvent more rapidly than in untreated solvent and the resulting clarified appearance enables the solvent to be used longer and more effectively in a cleaning operation.