Re: What did we do wrong?
We think we have it figured out. Upon processing larger orders there tends to be a bit of a wait in the rinse tanks after the desmut (before ano), becuase the ano process is so much longer than the cleaning steps. The first rinse tank after the desmut gets a fair bit of gunk in it from the rinsing process, and parts were being kept in it for the duration of anodizing another batch. While in there something was causing a reaction to occur with the surface of the aluminum and causing many little spots to be developed, which turns out to be the pitting observed. When the parts were pulled out ready for the next ano run it was fairly obvious that the spots shouldn't be there as all the parts remaining to be run were very non-spotted. What exactly was causing the pitting remains a mystery, but we now know how to avoid it.
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