Liquid cleaning techniques. Liquid cleaning can be very useful for removing gross contamination. Fluid cleaning techniques for polymer surfaces fall into three main categories: hand wiping, solvent cleaning, and water-based washing. Hand wiping can be done with a variety of solvents, combination of solvents, or an aqueous solution of various chemicals. This process is very labor-intensive and is usually only employed in situations with low production volumes. Hand wiping can result in inconsistencies in quality due to either human error or the redeposition of soils onto the surfaces being cleaned from contaminated rags used in the process. Surface treatment by solvent cleaning is most beneficial in those cases where swelling of the polymer surface, due to solvent absorption, results in a rougher morphology that can improve the adhesion of coatings without adversely affecting the substrate's mechanical properties. The process uses inexpensive equipment and works reasonably well in many cases such as in the surface preparation of molded polymer parts for subsequent paint adhesive, or coating application. Solvent treatment processes can be conducted through wiping, immersion, spraying, or vapor degreasing. Typically, high-vapor-pressure organic solvents (alcohols, ketones, toluene, etc), chlorinated hydrocarbon solvents (eg, Freons, or 1,1,1-trichloroethane) or low-vapor-pressure organic solvents (terpenes, isoparaffins, lactates, esters, etc) are used in these processes (2). The major drawbacks of the technology are the environmental and process hazards associated with the use of large quantities of volatile chemicals, to the extent that any savings in equipment cost are usually offset by the increased cost of obligatory environmental controls. Also, solvent-based surface treatment has limited utility when a distinct change in the chemical nature of the substrate surface is desired. Water-based cleaning processes operate with relatively low costs, have low environmental impact, and are well suited for high production volumes. An industrial power washer usually consists of an overhead or floor conveyor with parts mounted on racks that pass through various spray stages. Most systems are composed of seven separate functions: precleaning, cleaning, rinsing, conditioner or rinse aid, deionized water rinsing, air blow off, and oven drying (3). However, for most commercial applications this technology requires capital investment for new equipment.