Low contact angles with water may be obtained on the surfaces of chemically reactive metals by a process involving chemical cleaning with powerful oxidizing acids, followed by electropolishing to restore smoothness to the etched specimens. By using highly refined handling techniques, contact angles in the range, 0-11°, were obtained on aluminum, brass, copper, magnesium, nickel, stainless steel and zinc. The low contact angles are considered a good indication that organic contamination was virtually absent from the electropolished surfaces. The possibility of spurious inorganic contamination, apart from the normal oxide film, also was considered, and, in the case of copper electropolished in phosphoric acid, the residual phosphate on the surface was estimated by coulometric reduction and shown to be much less than a monolayer. The preparatory technique used in this study is applicable to a wide variety of metals and alloys and serves to demonstrate experimentally the inherent water wettability of clean metal surfaces. It also provides a means of preparing clean, smooth substrates on ^which fatty acids or other compounds may be deposited and their behavior observed in determining wettability and adhesion. Mechanical polishing, followed by exhaustive rinsing with hot or cold redistilled organic solvents, was not effective in producing low contact angles on metal surfaces.
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