Introduction

SOLVENT CLEANING is a surface preparation process that is especially adept at removing organic compounds such as grease or oil from the surface of a metal. Most organic compounds are easily solubilized by organic solvent and removed from the workpieces. In some cases, solvent cleaning before other surface preparations can extend the life of cleaning operations and reduce costs. In other cases, solvent cleaning prepares workpieces for the next operation, such as assembly, painting, inspection, further machining, or packaging. Before plating, solvent cleaning is usually followed by an alkaline wash or another similar process that provides a hydrophilic surface. Solvent cleaning can also be used to remove water from electroplated parts, a common procedure in the jewelry industry.

Solvent cleaning can be accomplished in room-temperature baths or by using vapor degreasing techniques. Room-temperature solvent cleaning is referred to as cold cleaning. Vapor degreasing is the process of cleaning parts by condensing solvent vapors of a solvent on workpieces.

Parts may also be degreased by immersion in the hot solvent, as well as by exposure to the solvent vapor. Drying is accomplished by evaporating the solvent from the parts as they are withdrawn from the hot solvent vapor. In cold cleaning, parts are dried at room temperature or by the use of external heat, centrifuging, air blowing, or an absorptive medium.

The use of many industrial solvents is being severely restricted because of health, safety, and environmental concerns. These concerns are discussed to some degree in this article; additional information is available in the articles "Environmental Regulation of Surface Engineering" and "Vapor Degreasing Alternatives" in this volume.

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