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Pitting occurs in the rinse after de-smut





May 16, 2011

Recently we have been experiencing pitting after anodizing process.We have done our analysis and found most of the pitting occur after the rinse tank immediately after desmut tank.We have changed a new water and added nitric acid to the bath but still have the pitting ocassionally. What could be the cause and how to remove permanently? What is the chloride content acceptable in the rinse and desmut tank?
Regards
Hanif

Hanif Hamzah
press metal - Klang, Selangor, Malaysia



Tell us the formula of the deox. Chloride seems to be your problem. Limits have not been published. I say under 50 ppm. However, how long are you staying in the acidic rinse water, what is the turn over, is there a galvanic voltage between the titanium rack and the stainless steel acid laden rinse tank?? There should always be two rinses between deox and anodize

robert probert
Robert H Probert
Robert H Probert Technical Services
supporting advertiser
Garner, North Carolina
probertbanner
May 19, 2011




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