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Cloudy surface after clarification in nitric acid
Q. Hi! Please tell me why a cloudy surface is obtained after clarification in nitric acid. I do bright color anodizing, but it turns out to be matte.
Andrey- Sarapul, Russia
October 6, 2025
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A. Hi Andrey.
I personally have not heard the word 'clarification' in this context. But you are probably referring to immersing the parts into dilute (1/2% to 1%) nitric acid as a way of driving out the sulfuric acid after anodizing and before dyeing?
I am surprised that this would cause a cloudy surface, and am not really confident that this is what is causing the problem of lack of brightness. Can you tell us what alloy you are anodizing, and about your etch bath (if applicable) and your non-etching caustic cleaner?
If other readers are familiar with a nitric acid dip after anodizing causing loss of brightness, please inform me as well as Andrey.
Luck & Regards,
Ted Mooney, P.E. RET
Striving to live Aloha
finishing.com - Pine Beach, New Jersey
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