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What is Nitric Acid used for in anodizing?

Can anyone tell me why a nitric acid bath is necessary in the aluminum anodizing process?

chris
- Hampton Virginia

It is not "necessary", it is a readily available cheap desmut chemical. Proprietary desmut/deoxidize chemicals are available, but at a higher cost. Most of them work better because they do two functions.

Probably the most effective deoxidize desmut is a mixture of sulfuric/nitric/ammonium bifluoride. Effective, but slightly nasty.

James Watts
- Navarre, Florida

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What mixture ratio do you mix -mixture of sulfuric/nitric/ammonium bifluoride- to make the desmutter and deoxidizer and where is the best place to buy these chemicals?

Roy Clarkson
- Rock Hill, South Carolina

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It's best to buy a proprietary desmutter from an aluminum pretreatment specialist like the website's supporting advertisers Chemetall-Oakite, Macdermid, or U.S. Specialty Chemical. One advantage is technical help -- they'll tell you how and where to control the composition and help you make sure you get it right. If you want to buy the raw chemicals yourself, any chemical supply house will have them. Good luck.

Ted Mooney, P.E.
finishing.com
Brick, New Jersey

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