Letter 2076

Removing anodizing from aluminum

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From time to time I have wanted to remove anodizing from aluminum parts. While I'm not certain what the precise nature of the surface treatments are, they're usually not hard anodized. I'm curious if there are any relatively simple ways, using readily available chemicles that can remove the treatments. While sanding and polishing do the job, it can be a very long job...

rob howard

There are 2 way to accomplish the removal of the anodic coating from aluminum depending on the surface you want to end up with. A NaOH etch solution will remove the coating but will etch the surface leaving a diffuse (matte) appearance. The chromic acid/phosphoric acid solution used in the Acid Dissolution Test ASTM - 137 will remove the anodic coating without affecting the underlying surface. The composition of that bath is 80 grams of chromic acid in 3.5 liters of water, add 140 ml of 85% phosphoric acid, add water to make 4 liters. The bath is operated at 190 - 200 deg. F. Immerse the part for 15 minutes and then rinse well in water.

Lee C. Branch
Richmond, VA

Would not a deoxidizer like 50% nitric do the job?

Bob Morrison
Ormond Beach, FL

Don't anybody know that good old oven cleaner has just enuf acid to remove most anodizing with out pitting or discoloring the alluminum surface (it works try it).

Ken Perrella
- Utah

Actually, that is not so. Oven cleaner is very caustic, and will remove anodize, but I have found it difficult to control, and makes for a really ugly resulting finish. Completely undecorative.

Tom Pullizzi Platronica.com Falls Township, PA

 

I used oven cleaner on my oxidized frame on my GSXR and it didn't remove it. I sprayed it on and let it sit for 15 minutes and it did absolutely nothing. Sanding has been the only thing that will work.

DAVE L
- BRISTOL, RI, U.S.

Oven cleaner DOES work quite well. But Anodizing is the second hardest substance known to man, its going to take longer than 15 minutes!! I recommend atleast 45 minutes, after that you will actually see the anodizing fall off. And depending on the aluminum underneath, it sometimes does leave a horrid finish. But for a Motorcycle, since I am assuming you were polishing the frame on the GSXR... the resulting finish would NOT matter because the plan is to sand, cut and polish. I am sorry you spent the whole weekend sanding off the Anodizing, if you had given the oven cleaner another half an hour, you could have saved some elbow grease.

Steve Callen
- Walton, Kentucky, USA

I am an amateur motorcycle enthusiast in need of some advice/insight. I recently purchased an 89 gsxr-750. The swing arm has already been stretched 6 inches and chromed. I would like to polish the frame of the bike, but I do not know what to do to get that annoying anodized coating off. Also would you recommend wet sanding the frame after stripping the anodized coating? I started working on a 6 inch section of the frame where the fairing will be covering just in case I botched it. At least this way I can cover it up. Any advice would be greatly appreciated.

Jamie Dalmida
Hobbyist - Boynton Beach, Florida, United States

I am restoring a 1963 Chevorlet 2 door hardtop Impala. I have been able to clean and shine all of the chrome and steel, but am unable to clean the anodizing from the aluminum trim. I have buffed some of the trim, also have tried to clean and shine, but it will not come back to a good shine. Does anyone know how to remove the anodizing from the aluminum trim? I would be grateful for any suggestions.

R. Gerald Scales
hobbyist - Bowdon, GA, USA

I've used oven cleaner to remove anodizing on different bicycle components. A pair of Sugino cranks and a pair of DA hubs. the oven cleaner (zipp professional from home depot) took it off of the cranks in a few minutes. it took a lot longer and more steel wool to get it off of the hubs. I don't know if the coating on the hubs was thicker or if they had used some kind of sealant, but there was no mistaking the difference in time it took.

John McComb
- Oakland, CA, USA

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