Ask the Expert Question-and-Answer Archive

by Ron Joseph

January, 2005

Wash Primer and Chemfilm

Q. Is a wash primer required with the use of chemical film per mil-c-5541 on aluminum when painting per mil-t-704?

A. Thanks for your email. You should not need to apply the wash primer if you have already applied a chromate conversion coating such as Chemfilm. In fact, the application of a wash primer can weaken adhesion between your primer and the substrate because excessive phosphoric acid might be present at the interface.

Best wishes,

Ron Joseph