Hello hogan, the only other "thing" that comes to mind for me here, would be residual stresses in the material. If this is 6061T-6 it would be heat treated and could possibly have some internal stresses that are being released by the anodizing process. These are just thoughts on my part and I don't have any sort of "proof" that this is actually what is happening. Best regards, Allan
Wow, this is really odd.
What did the two coating companies have to say about it??
I'm really interested to hear the root cause, we have a fair amount of this done and do not want to go through what you are.
Keep us posted.