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Black tiny patches on the anodized aluminum sections

2006

In the process of anodizing aluminum sections AA6063, after rinsing them in the etch bath
(ALKALINE), some tiny black patches appear on the whole surface of the aluminum sections.
We have kept the related concentration and temperature in the standard limit. Even in case we changed the time duration of etching, no result was achieved.What is the reason and how it can be solved?

Ms. Montazeran
- Arak, Iran

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Hi Montazeran,

I think, you are talking about smut layer formation after etching. You need to desmut the job after etching. Dilute Nitric Acid may work well. i.e..... Etching - 2 water rinses - Desmutting - water rinse......

Keshava Prasad M
- Chennai, India
2006