removing anodising

This post is worthless without pictures, weiser.

Just sayin'....

What are you guys doing after you get the anodizing off or is that the final effect that you are looking for?
Just wondering if you are re-anodizing as in the RIT dye thread.

That's the correct spelling in proper English - after all Charles is English... :P

Greased Lightning. Use straight out of a 1 gallon bottle. Don't dilute, but just have a bucket of water to rinse. Much safer! I did not notice any strong fumes, but I did it in a well ventillated area. I wore gloves and goggles. I just set the light parts in it for 15 minutes and then I used a small brass brush and let it sit again till all ano was gone. Rinsed it in water and then alcohol. All I needed was steel wool to clean up the residue.

I do not know if you can get it in the Uk, but you may have something similar. I can post the ingredients if you need. 2-Butoxyethanol

I can't see a mechanism by which 2-butoxyethanol could strip out anodisation. It will help with removal of the organic dyes used to colour the part after anodisation. Aluminium oxide isn't soluble in things (any organic solvent that I know of) other than mercury and strong alkalis.

According to the MSDS (page 6), it contains sodium hydroxide which is the strong alkali doing the work here. This is obviously a major part of the ingredients of "Trade Secret 762" mentioned on p.2 though with a pH of 12.5-13 there are buffers in there as well as caustic soda. Otherwise the pH would be very much closer to 14. My guess is that it contains 1-2% sodium hydroxide by weight.

My personal preference is just to use sodium hydroxide - but then I used to be a chemist. It is cheap and widely used for paint stripping. Just remember when making up a solution that you add the solid sodium hydroxide to water, in small amounts at a time. You always add nasty stuff to water, not the other way round. See the warnings above.

Old plastic soda bottles are useful for stripping torch parts - just cut the top off and you have a suitably sized cylindrical container to dunk the parts in.


You are absolutely correct. What scares me is the knives, drills and saws that the other members use!

(just kidding) Actually what is scary is the unknown, Any tool in the hand of an unskilled operator is dangerous.

To most people, Chemicals are scary. If one wants to worry about a chemical, just consider Dihydrogen Monoxide!

BTW, When de-anodizing aluminum, dihydrogen monoxide IS present!

Penn and Teller had a bit where they asked folks to sign a petition to ban DHM.

Great stuff.

FWIW, the label lists "alkaline builders" as an ingredient. Likely lye, sodium orthosilicate, or TSP.

EDIT: The caustic chemical is likely not just sodium hydroxide, as the LD50 is vastly different. (Oral, rat: 345mg/k vs 1350mg/k)

Anybody tried Mr. Muscle oven cleaner for this? I'm pretty sure it contains sodium hydroxide - I know a lot of VW guys successfully de-coke their diesel turbochargers with it!

I have used E-Z-OFF oven cleaner with good results.

Once again, be careful with the more caustic of these chemicals. They will saponify your very flesh.

Personally I prefer the straight stuff, so I know what I'm dealing with. That said, just about anything that can decoke engine parts will eat aluminium quite happily. Usual provisos - keep the stuff off your skin and eyes. Those burns hurt. I don't like using thickened stuff as most oven cleaners are as it is harder to get them off a) skin and b) the piece you are working on.

Metallic mercury works really well for stripping anodising. And dissolving all sorts of metals - like gold.

But has other drawbacks, not least what the stuff costs. At $80 per kilo (around two fluid ounces / 60ml) on the spot market which probably means four times that from anyone prepared to sell you the stuff. Which will not be easy as the stuff has some unpleasant habits.

It's funny you should mention Penn and Teller,

I mentioned them today (April 1st) in another post.

Got Me!

"BTW, 25 Years ago or so, There was an ad on the back inside page of a PC type magazine, i forget which one, but it was an ad for a 33Mhz Compaq with a 500MB drive and 1Meg

of memory, etc. A very impressive machine at the time. The advertised price was $2500.00 or so, also a Very, very good price. Should have been about $7,000. There was an 1-800 number to call to order.

Turns out the 1-800 number was a recording of Penn (of Penn and Teller) Saying April fools, how could you be so gullible etc. Then I remembered that Penn had a monthly column

in the magazine in that very same location. He used this months column (April) as an April Fools prank. I had a lot of fun passing that ad around."

Now I’m the one to bring this thread to life, which has been buried twice already…

Don wrote: “Make up a strong solution…”

What exactly is strong (strong enough for a reasonable timescale, but not too strong to eat the aluminium).
I got granulated NaOH (white stuff…), box says 98% NaOH, 2% other. How much do I take?

I don’t need something sophisticated like mol/l, honestly I don’t want to have to weigh this stuff because I am very aware of its power, so I’d like to handle it as little as possible. Something like teaspoons per litre would be incredibly helpful.

Thank’s a lot.

In my experience I use about 1/2 teaspoon per cup of water. That maybe a little stout but I’am impatient.
I usually dunk the part in the solution and pull it out to check it every minute or so to see how well its doing. It should make tiny bubbles when its working and the top of the solution will start to turn the color of the anodizing. I assume this is the dye being released in the solution. It will start out kind of slow, but as the anodizing starts to dissolve the bubbles should increase. If the mixture doesn’t strip the anodizing after about 10 minutes I add a little more caustic soda. When I strip the anodizing off a D Maglite tail cap so that the spring can set in the bottom of the tail cap. I just pour water in the tail cap and add about 20 granules or so of caustic soda wait about 10 minutes and presto bare aluminum. Don may have a exact mixture. I Just use a mixture that will work in a timely fashion. Don’t leave it in the solution and walk away, It can eat through the anodizing and keep going, eating the aluminum. Threaded anodized parts can become sloppy when de anodized. Because of a few thousandths being lost when de anodized, Those extra thousandths from the anodizing layer where accounted for when the part was made and designed to have acceptable thread clearance. With out the anodizing layer you lose a few thousandths making the thread clearance greater. It’s usually not all that bad with threads but it can be if left to long in the solution. Leave it just long enough to remove the anodizing and then rinse. Just my 2 cents.

I’ve always wondered about a similar thing (but never asked), i.e., do you need to do anything to preserve the surface after stripping the anodizing, like polish or something?

Bare aluminum will oxidize in a matter of seconds when exposed to oxygen. Leaving a very thin layer of oxidization. Anodizing is essentially the same thing only with a much thicker layer and the ability to dye the honey cone shaped layer giving the aluminum the appearance of color. When sealed the color (dye) gets locked in those honey cone shaped formations.
No further treatment is necessary, it takes care of its self in oxygen. I would recommend that if you do polish aluminum that you a apply a coat of wax. That should help retain its luster longer and keep finger prints or water spots from showing up.

I’m looking into possibilities of modding a certain light to QTC twisty. But the light has anodized threads.
If the anodization is stripped off the threads, will the material loss make the threads work worse?

Have you a local machine shop that is equipped with a glass bead blast cabinet?

No chemicals involved, only a dust mask which we are already wearing

Have operator use recycled (extra fine) glass bead media… and important to use Low PSI on soft Al…

You can hand polish smooth machined areas if desired

Good luck!

Yes, you’re correct it would be hard to get ano completely out of knurling. You would still end up using chemicals to finish cleaning…

I made a DIY blast cabinet out of plywood and plexyglass. My compressor is a little small in CFM, so takes awhile but eventually gets the job done

Post some photos when you are finished

@Agro I think the threads will work equally with or without ano. Although I’d be concerned about some chemicals could eat up Al making the threads fit loose

Watch the Al surface isn’t overly dissolving… and open a window