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Thread 495/63
Flaking Chem Film
August 6, 2008
We are currently using Chem Film for a primer/corrosion inhibitor for a painting process on an aluminum plate. We are having issues with what seems to be flaking of the Chem Film after the paint baking process. The paint is only applied to a portion of the part. The flaking of the Chem Film is happening in the non painted areas. The provider of the Chem Film blames the bake process (being to high at 400 degree F) and the Painter blames the cleaning process before Chem Film. The flaking looks like and is the size of a head of a pin. The material used is aluminum sheet and the manufacturing process is stamping.
Best regards,
Kevin Brown- Carol Stream, Illinois
publicly reply to Kevin Brown
First of two simultaneous responses --
The problem is the chromate is a hydrated jell. It lives well under the paint, but the exposed part dehydrates above 140F. $00 is well above 140, so you will have a problem. The plater is not at fault.
James Watts- Navarre, Florida
August 6, 2008
publicly reply to James Watts
Second of two simultaneous responses --
You cannot heat bare aluminum chromate without dehydrating the coating and causing it to flake off. Go read the military specification for confirmation of this statement.
Robert H Probert
Robert H Probert Technical Services
Garner, North Carolina
August 6, 2008
publicly reply to Robert H Probert
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