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Black Chromating Process

We use acid zinc as our main production. We have a problem in black chromating process, on the surface of the part we found several white spots. Why ?

Kasmin Gurning
- Cikarang, Jakarta, Indonesia
2001

Kasmin first are you using a proprietary silver nitrate black chromate? Second, following rinsing after plating what are you using for a neutralization step, dilute acid? Are you rinsing in a tank following the black that is clean? Is this an automatic machine or hand line?

Bill Hemp
tech svc. w/ chemical supplier - Grand Rapids, Michigan
2001

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