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Chrome Plating that is pitting, but not "gas pits"

I have some questions relating to chrome plating on a sealing surface for aircraft seals. We require Chrome Plating per AMS2406 and have recently had problems with what we thought was "pitting" in the plating. After some analysis by a test lab the initial thoughts were "pulloff" due to a much too aggressive grinding setup at our facility. However we noticed voids (not gas pits) within the plating that did not go all the way through to the base metal. They almost seemed suspended in the middle of the coating. Now I am still a believer that our grinding process isn't bulletproof, but I am curious as to what has caused these voids in the coating process. I will wasn't able to attach some pictures for reference, but I have them to email if anyone would like (I know pics are so much easier to work with). My vendor hasn't been extremely helpful in identifying the issue so I thought I would post here and ask the experts (which I am most definitely not). Thanks for the responses in advance.

Marc C
Supplier Quality - Chicago, Illinois
January 30, 2009

Please attach to pics to an email to mooney@finishing.com, Marc.

Look at several pits with a 10X glass and oblique light. See if it looks like there is the remnants of a tree stump near the center of the pit. If it does, I can give a very good guess at the cause.

James Watts
- Navarre, Florida
February 2, 2009

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February 6, 2009

Hello,

I did not open this Topic but I am also interested to know what could be the root cause for the tree stumps?

kind regards
Atze

Atze Schröder
- actually Poland