Removing Anodizing?

[A-Town]

Anyone know how to remove anodizing from aluminum parts? I've heard oven cleaner works, but I haven't tried it yet.

[tryandgetme]

dremel, sandblaster, etc ;)

[A-Town]

dremel, sandblaster, etc ;)

Nah, I want to leave it raw after I take the anodizing off. I'll clearcoat it ofcourse.

[BrevCampagnolo]

Depending on the part and the type of anodizing, you could be grinding off a substantial amount of structural integrity right along with it.

[bunn]

I know very little about anodized parts, but I do know that automobile brake cleaner will eat the finish off everything you drip it on, including your hands.

[The Rose]

If I remember right carburator cleaner will take the blueing off a rifle. It may work the same for anodizing.

[ThingTwo]

I faded a black AVID brake lever once with rubbing alcohol (imagine if it were 100% alcohol). I think it was anodized?

[Tommy_G]

I found this on Fixedgeargallery.com Seems to be the stuff for the job


http://www.fixedgeargallery.com/articles/polishing/


Tommy G

[Trailer Rails]

Oven cleaner does work. I used it on a pair of RF Turbine cranks. It leaves a blotchy finish which takes a lot of work to clean up. I ended up rattle-canning them. You might need some kind of industrial polisher to clean them up.


You are right, I have never experienced the blotchy finish. :D

[A-Town]

I found this on Fixedgeargallery.com Seems to be the stuff for the job


http://www.fixedgeargallery.com/articles/polishing/


Tommy G

This looks liek the easiest thing to do. I just ordered a bottle. It was like $20 after shipping. I'll let you guys know how it turns out.

[Spatafore]

I think that anodizing makes the surface porous thus enabling the dye to bite into the alloy. Anodizing also hardens the surface of the material. Odds are, all you are going to do is ruin whatever you try to remove the anodizing from. I could be wrong though...

[rockyrider]

Anodizing actually forms an aluminium oxide coating on the surface of the piece, which is something like 0.003" thick, so it is a harder surface than raw aluminium and resistant to further corrosion. It's only porous and accepting of dyes until it's sealed in the final step of the anodizing process.

Anodized aluminium

Aluminum is anodized both to increase corrosion resistance and to allow dyeing.

While pure aluminum creates a natural oxidation layer its alloys are more prone to corrosion and are therefore annodized to increase the thickness of this layer for corrosion resistance. Most aluminium aircraft parts including major components are anodized. Anodized aluminium can be found in many consumer products like mp3 players, flashlights, cookware, cameras, sporting goods, and many other products both for corrosion resistance and the ability to be dyed.

The aluminium oxide coating is grown from and into the surface of the aluminium. Because of this it is not prone to peeling or cracking like organic coatings such as paint. In most consumer goods the dye is contained in the outermost portion of the Aluminium oxide layer. While highly wear resistant the anodized surface can still be worn. If wear and scratches are minor then the remaining oxide will continue to provide corrosion protection even if the dye is removed.

Dyeing

Where appearance is important, the oxide surface can be dyed before the sealing stage, as the dye enters the pores in the oxide surface. The number of dye colors is almost endless; however, the colors produced tend to vary according to the base alloy. Though some may prefer lighter colors, in practice they may be difficult to produce on certain alloys such as high-silicon casting grades and 2000-series (with its high copper content). Another concern is the lightfastness of organic dyestuffs—some colours (reds and blues) are particularly prone to fading. Black dyes and gold produced by inorganic means (ferric ammonium oxalate) are more lightfast.

Alternatively, metal (usually tin) can be electrolytically deposited in the pores of the anodic coating to provide colors that are more lightfast. Metal dye colors range from pale champagne to black. Bronze shades are preferred for architectural use.

Alternatively the color may be produced integral to the film. This is done during the anodizing process using organic acids mixed with the sulfuric electrolyte and a pulsed current.

After dyeing, the surface is usually sealed by using hot water or steam, sometimes mixed with nickel acetate or other anti-bloom agents, to convert the oxide into its hydrated form. This reduces the porosity of the surface as the oxide swells. This also reduces or eliminates dye bleed out and can increase corrosion resistance. Sealing at 20 °C in nickel-cobalt salts, cold sealing, when the pores are closed by impregnation is also popular due to energy savings. Coatings sealed in this method are not suitable for adhesive bonding.

A friend of mine pointed out years ago that you can do a "poor man's anodizing" by putting a raw aluminiim part in a dishwasher and it will speed the development of a matte finish aluminium oxide layer over the surface.

More on DIY anodizing here

http://astro.neutral.org/anodise.shtml