GMNA GM9040P PDF

1 SCOPE.

This test method (commonly known as the EC Test) was developed by the GM Research Laboratories to provide a rapid and accurate means for evaluating the corrosion protection characteristics of copper-nickel-chromium and nickel-chromium electrodeposits on exterior car parts, including flat and contoured shapes and brushed finishes. Experience with such finishes shows that corrosion produced in two minutes electrolysis (current-on) time in this test approximates the extent of corrosion normally developed in one year of outdoor service in the Detroit Metropolitan area. It indicates, also, that the method is applicable to other electrodeposits and those of lesser and greater thickness by appropriate adjustment of electrolysis time.