Type I: As plated.
Type II: Supplementary chromate treatment. Type II plating shall not show white corrosion products od cadmium, pitting, or basis metal corrosion products at the end of 96 hours (20%) salt spray exposure per the following table:
Type Class Test period for white corrosion products (hours)
Type II 1 96
Unless otherwise specified, chromate treatment required for Type II is distinctly colored iridescent bronze to brown including olive drab, yellow and forest green.
Type III: Supplementary phosphate treatment. Type III shall conform to Type I of TT-C-490. Type III is used as a paint base.
Class 1: .0005” minimum thickness.
Class 2: .0003” minimum thickness, additional thickness requirements are given in paragraph 3.3.1 amendment 2 of this specification.
Class 3: .0002” minimum thickness.