Ask the Expert Question-and-Answer Archive

by Ron Joseph

December, 2004

Surface Preparation of Aluminum

Q. Would you expect to find chlorides present between a properly cleaned 6061 Aluminum surface and a CARC primer?

No, I would not expect to see chloride contaminants on the aluminum surface under the CARC paint. Without knowing more about the problem I am guessing that tap water was used during the rinse stages of the pretreatment and that a seal rinse using deionized water was not used. Another alternative explanation is that if the CARC system had been exposed to a marine environment, chlorides migrated through the film to the aluminum surface. Of-course, if the coating system had not been exposed to a marine environment, then this explanation falls away.

I would be interested to hear more about the problem.

Best wishes,

Ron Joseph