Summary for anodizing aluminum with formic acid Discussion
Anodizing aluminum with formic or citric acid is raised as an alternative to sulfuric acid, but the thread excerpt provided does not include the actual technical discussion or conclusions. The only visible content is the forum header and a pointer to a related topic, “Alternative to sulfuric acid for anodizing aluminum,” suggesting the page is part of a broader discussion about substitute anodizing electrolytes. Because the answer text is missing, no specific process guidance, performance comparison, or recommendation can be reliably summarized from this excerpt alone. The source does identify Ted Mooney, P.E. as the forum host, but no substantive advice from him appears in the provided text. For an accurate takeaway, the full thread would be needed to determine whether formic or citric acid was endorsed, discouraged, or discussed only as a theoretical possibility.
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Aluminum How-To
“Chromating – Anodizing – Hardcoating”
by Robert Probert
You’ll love this book. Finishing.com has sold a thousand copies without a return request 🙂
Q. Hi, I would like to ask whether it is possible to anodise aluminium using less aggressive acids than sulfuric such as formic or citric.
John Payton
– Norwich, Norfolk, England
2006
A. To me, the two nastiest acids are hydrofluoric and formic, so I would not even start to consider formic.
Less aggressive acids might be phosphoric or boric/sulfuric. Literature is available on both.
James Watts
– Navarre, Florida
“The Surface
Treatment &
Finishing of
Aluminium and
Its Alloys”
by Wernick, Pinner
& Sheasby
on Amazon
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A. Hi John. It is possible to anodize in just about any acid — if by ‘anodize’ you mean make the part anodic and build some sort of film on it — because almost any acid will conduct electricity. But the characteristics of that film will vary tremendously based on the anodizing conditions and they would not approximate the film formed in 10-12 percent sulfuric acid.
Remember that in sulfuric acid anodizing the sulfuric acid is constantly attacking and dissolving the anodized film, leaving a honeycomb type structure, and other acids may not dissolve the anodizing i a similar way.
tartaric acid
⇦ on
or
Amazon [affil link] , phosphoric acid, chromic acid and boric acid are a few of the commercially used acids, but the coating does not look or function anything like a sulfuric anodized surface.
“Aggressive” toward human biology and aggressive towards aluminum are not the same thing, and I’m not sure which you mean. Good luck.
Ted Mooney, P.E.
Striving to live Aloha
finishing.com – Pine Beach, New Jersey
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Readers may wish to also see:
• Topic 43230 “Alternative to sulfuric acid for anodizing aluminum”