Metal finishing Q&As since 1989

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Out-gassing in aluminum castings

2004

I am looking for a solution that may not exist having to do with out-gassing. I am trying to coat some old, irreplaceable aluminum castings that were badly corroded and pitted. The usual abrasion blasting, cleaning and, high temp out-gassing for hours has been done. I am also using an OGF additive in the powder which does help. I am first coating with an OGF supplemented epoxy primer with partial cure before the final color coat. I have also tried coating hot without increasing the temperature but it is difficult to keep small aluminum parts from cooling rapidly before the coating is completed.

I am wondering if there is some other process I might try such as a hot immersion bath of some sort or a low temperature surface sealant that would be compatible with powder, or any other ideas.

Larry Johnson
- Key West, Florida

Try applying a two pack wash primer - try your local paint supplier or car refinishing supplier. This will seal the surface of the casting. Mix in the ratio recommended. Apply a thin wet film - allow to air-dry -apply powder etc.

Terry Hickling
Birmingham, United Kingdom
2004