Removal of Difficult Soils

Virtually all ordinary oils and greases are soluble in chlorinated hydrocarbons and can be completely removed by one or more of the methods illustrated in Fig. 2. Other types of soils vary in responsiveness to vapor degreasing, from mild to almost total resistance to solvent cleaning.

Frequently, vapor degreasing is used to remove soils that do not dissolve in the solvents. Among these difficult soils are pigmented drawing compounds, water-based cutting fluids, chips, polishing and buffing compounds, and soldering fluxes. In some instances, it may be possible to substitute more easily cleaned materials. When insoluble soils are encountered, the solvent cleaning may need to be supplemented by mechanical cleaning. Impingement with a spray will remove some insolubles. Brushing may be practical in some situations. Finally, ultrasonic cavitation in the warm dip chamber can often remove the most tenacious soils.

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