Metal Finishing Guide Book


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SAFETY As with any laboratory procedure, the accepted safety rules for handling acids, bases, and other solutions should be followed. Acids are always added to water, not the reverse. Mouth pipettes should not be used for pipetting plating solutions. Safety glasses should always be worn, and care should be exercised to avoid skin and eye contact when handling chemicals. A fume hood should be used when an analytical method involves the liberation of hazardous or annoying fumes. Laboratory staff should be well versed in the first-aid procedures required for various chemical accidents. DETERMINATION OF CATHODE EFFICIENCY The procedure for determining cathode efficiency, using the setup pictured in Fig. 1, is as follows: 1. Connect the copper coulometer in series with the test cell. 2. The copper coulometer solution should contain 30 oz/gal copper sulfate pentahydrate and 8 oz/gal sulfuric acid. 3. Use the same anodes, temperature, and agitation in the test solution that are used in the plating bath. 4. Plate at 0.4 A (30 A/ft2) for a minimum of 10 minutes. 5. Rinse both cathodes, dry in acetone, and weigh. % Cathode Efficiency = weight in grams of test metal X valence of test metal in bath X 3177 weight in grams of copper metal « atomic weight of test metal *Editor's note: To view this article in its entirety, including corresponding tables, please consult the online Guidebook archive. 493

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