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Black spots on one side of thread after Anodize and Dichromate Seal

Q. We have an issue with small black sots that are only visible after the anodize process. We machine 6061 and send it out to plate. If this was corrosion wouldn't it show up in different areas? They only appear on one side of the thread. (through hole)

61811-1a 61811-1b 61811-1c

We sent some to be tested but I'm 10 days out from an answer. Looking for help.

Bobby B
GM - Odessa, Florida
February 25, 2025

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