Instructables

Removing Anodizing From Aluminum Quickly and Easily.

Step 4: Admire Your Clean and Beautiful Parts.

Remove your parts from the solution using a tweezers or hook. Run it under cold water until there are no more suds. Pat dry with a towel or paper towel.

Look at your clean, non-ugly parts. Great!

Oh bother. Now you have to put the thing back together.
Tigertouf3 months ago

Hi Daniel,

I'm really happy to have found this instructable. Although I do have a question:
Once the dye is fully removed, can I just dye the aluminum another color?

I'm currently debating of deanodizing the alloy parts of an RC car chassis and change it to a different color. Could I just follow your procedure and dye it with clothing dye?

swander8 months ago

Tried liquid plumber, couldn't get Lye at grocery store at 8PM on a Sunday. Soaked my 1965 headlight bezels in the stuff straight and it didnt do squat. I soaked for another hour and the anodizing is finally starting to feather off with sandpaper. Fast, I wouldn't say that. Easily? Not with Liquid plumber and it did contain Sodium Hydroxide. So maybe I got some weak sauce...Ill soak overnight. Even a sanding flapper wheel on a die grinder didnt just wipe this stuff off!

Sodium hydroxide is also know as Lye, which is used to make soap and is also used in things like oven cleaner and other heavy duty cleaners. You can buy pure lye in flake form, used for clearing drains, at most hardware stores. Mixed with water, it will strip anodizing.
MrSquirrel1 year ago
Hey, sorry I forgot to report back. The Multi-Purpose did not remove the anodizing, but it did change the surface texture of the metal.
MrSquirrel1 year ago
I know this post is old, but I have one question. Can I use Multi-Purpose Greased Lightning, or do I have to use the Auto and Shop that you used?
daniel_reetz (author)  MrSquirrel1 year ago
I don't know - but please report back if the Multi-Purpose works for you.
tsyed11 year ago
Hello guys ... I know it is a very old post but may be someone can reply ... I hope daniel_reetz is still around :-)
As you might already heard about anodize coating on the back aluminium of black iPhone 5 is susceptible to scratches. I've already dropped it once and got nasty marks on the corners. I'm thinking about removing this black anodized coating myself. What is the best method to do that, considering that I can't dip it in something? It has to be removed neatly and completely. Another thing I wonder is would I get a nice silver aluminium (like MacBooks) or some greyish silver aluminium?
daniel_reetz (author)  tsyed11 year ago
That's a very interesting idea, but I have no good idea on how to do it. Even the mild solution I mention here is a bit corrosive, so you definitely don't want any going inside the phone. Perhaps applying it with a slighly dampened Q-tip could control the fluid enough to make it work. I can tell you this, it will take time. Good luck!
Thanks for replying daniel. Couple of more questions :-)
Would a mild solution have any effect on plastic parts?
You said "it will take time", are we talking about minutes or hours?
Your knife appears white after the treatment not silver, like aluminium, why?
One comment below said "I think what you really did was remove the dye, not the anodizing". Does that mean my phone's back might not actually become silver?
shenrie12 years ago
...or you could just use paint remover...I accidentally discovered this today D:
I just soaked grease covered anodized parts in Lestoil to remove the grease and tar. It started foaming after 10-15 minutes and after 30min it had removed the red anodized color. I'm not sure if it is just leaching the color or stripping the anodized layer. Does anyone have any idea how/why a cleaner like Lestoil would have this reaction? It seems weird that a grease cleaner safe enough for laundry and mopping would have the power to do this.
junits153 years ago
oven cleaner works well also, but its really nasty stuff
oven cleaner is terrible. a few years back on a news program here in sydney a lady got some on her skin and it literally ate away at her flesh. she had a good 2 inch deep crater in her calf muscle. it was terrible
spyderbyte3 years ago
I have heard that both drain cleaner such as Draino and oven cleaner will remove the anodizing on aluminum. I am re-finishing the aluminum trim on my antique automobile and have been told that once you have removed the anodizing the aluminum can be polished and then protected with a clear spray plastic sealer. I've seen the finished product and was impressed. Does anyone know what to use for the plastic sealer to maintain the polished look?
deega4 years ago
No need to scrub.  Just get some drain cleaner (sodium hydroxide), the granule type, and mix with water to whatever strength you desire.  Dip the anodized part into the solution for about 15 seconds and rinse with fresh water.
Great 'ible! I would have never thought that something like this was possible until i saw this. +4.5!
I think what you really did was remove the dye, not the anodizing. The anodizing is actually aluminum oxide - which if you look it up, is one of the various abrasives used in sandpaper etc - e.g. "it's hard". I don't think a simple cleaner removed it... of course I'm surprised it removed the dye, so I don't know for sure ;-D Anyway, it WAS an ugly color!
daniel_reetz (author)  sr1sws5 years ago
Actually, you'd be surprised -- you can remove aluminum oxide with pretty much any caustic. Most people use oven cleaner, which contains sodium hydroxide (lye). Just like you, I doubted that it would work -- so before I spent the money on Greased Lightning I called my dad (he's a chemist) and he assured me that any base should eventually destroy it. I can ask him for the reaction and post it here if you're interested. Might be a nice addition to the instructable.
Actually, reading the link you included, this process oxidizes the aluminum, which softens the anodizing. You need to sand and polish the aluminum to get rid of the white Aluminum Oxide.
daniel_reetz (author)  plasticbiker5 years ago
The first step in the commercial production of aluminum is the separation of aluminum oxide from the iron oxide in bauxite. This is accomplished by dissolving the aluminum oxide in a concentrated sodium hydroxide solution.

From my dad, a chemist:

"Aluminium oxide reacts with a solution of sodium hydroxide to yield a solution of sodium tetrahydroxoaluminate. Al203+2NaOH+3H2O --->2NAlOH4 "

The whiteness of this surface is due to the bead blasting that they did pre-anodizing.
daniel_reetz (author)  daniel_reetz5 years ago
Ah, Google is my friend. Here's the reaction with sodium hydroxide. I'll check the MSDS for Greased Lightning and figure out the active ingredient.
daniel_reetz (author)  daniel_reetz5 years ago
The MSDS (material safety data sheets) for Greased Lightning indicate that the active ingredient is sodium hydroxide. There's also a "proprietary surfactant" which probably increases the speed and efficacy of the reaction between the aluminum oxide and sodium hydroxide.

Sweet.
dchall85 years ago
I wonder if ammonia would do it...maybe take longer.
Scott_Tx5 years ago
You should note that the surface anodizing hardens the surface of the aluminum. Scratch prevention and all that. But aluminum is self anodizing on exposure to air so it'll eventually turn gray and take on light surface hardening again.
daniel_reetz (author)  Scott_Tx5 years ago
Good point. I did leave out the fact that it will self-anodize a little, and that this process definitely reduces the scratch-resistance of the surface. However, one good thing is that if you scratch the surface, the underlying material is now the same color. Hence scratches are much less obvious.
misformiche5 years ago
agreed. dead sexy... roar.