This two-component zinc chromate pigmented, polyvinyl butryl coating. It serves as an excellent bond coat to many surfaces including aluminum, galvanized metal, lead, brass, magnesium, and other porous metals. This product is transparent yellow meeting specification MIL-C-851C.
S-75 is a zinc chromate vinyl butyral washcoat (sometimes referred to as a metal wash primer) used as a pretreatment for metal. S-75 is applied in a thin transparent coat since an excessive build-up will cause a lack of adhesion. S-75 Alumi-Chrome Primer should be topcoated after an hour and never applied when conditions are right for sweating of the metal or when moisture is present, since S-75 is moisture sensitive.