Metal Finishing Guide Book

2011-2012 Surface Finishing Guidebook

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Page 504 of 707

attacking the coating and decreasing the cell voltage. The decreasing cell voltage is integrated over time, yielding a comparative result. Weatherometer (ASTM G 23) This test is utilized to evaluate the performance of paint and lacquer systems under simulated outdoor exposure. The test yields data on the resistance of the coating sys- tem to condensation effects (rain) and the stability of the pigment in the paint (col- orfastness) when exposed to sunlight. Intense ultraviolet radiation from twin car- bon arc lamps and variant humidity levels (cycling from approximately 70 to 100% relative humidity) provide long-range test results in a short time frame (100-2,000 hr). Lactic Acid Lacquered brass- and copper-based alloys are tested for porosity and resistance to tarnishing by everyday handling (perspiration), using this test. Although not ASTM standardized, the procedure is gaining industrial acceptance. The principal mechanism is chemical attack. The procedure is as follows: 1. The item is dipped in a room-temperature solution of lactic acid (85%) saturated with sodium chloride. 2. The item is air dried for 2 hr in a convection oven at 120O F. 3. The item is suspended in the air above 100 ml of 30% acetic acid in an airtight chamber (desiccator). An acceptable substitute is the vapor VERSATILE AND REPEATABLE TESTING Auto Technology Cyclic Corrosion Test Chamber • Salt Fog High Humidity Dry-Off Dwell Solution Spray Controlled Humidity Immersion 22 0026 Progress Drive, Strongsville, OH 44149 • Ph: 440-572-7800 • Fax: 440-572-7820 503 CCT T est Cycles All Non-Corrosive Construction W e No w Pr o vide Contract Corr osion T e sting Ser vices

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