removing anodising

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charlestt
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removing anodising

What's the easiest way to remove anodising and what are the chemicals involved ? i'm based in the UK so will need to know what chemicals are being used so i can find an equivalent over here. I have had a look on google but can only see cleaners used in the US which are not available over here.

 

Many thanks

 

Charles

 

 

 

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fishinfool
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If anyone can answer this question, it would be BLF's own chemist.......Don.  (insert clapping smiley here)

 

Don wrote:

"But as I said long ago, you are more likely to be killed by a dead fish dropped by a seagull in the Sahara Desert than by a lithium ion

Don
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charlestt wrote:

What's the easiest way to remove anodising and what are the chemicals involved ? i'm based in the UK so will need to know what chemicals are being used so i can find an equivalent over here. I have had a look on google but can only see cleaners used in the US which are not available over here.

 

Sodium hydroxide - AKA caustic soda. You'll find it in B&Q as it is the standard means of unblocking drains. Read the warnings on the container. Follow them. The reason it gets used for unblocking drains is it destroys most organic material. Remember your flesh is organic material. If you want to keep it - keep sodium hydroxide solutions away from it. It is also often sold for paint and varnish stripping for the same reasons. Soap is made by boiling up fat in sodium hydroxide which is why alkalis feel soapy - they are converting your subcutaneous fat to soap. If you dissolve one crystal in a couple of pints of water you can get the feel with no danger. Just rinse your hands afterwards.

 

The container will say something like below. Believe it and follow the instructions.

Wear rubber/vinyl/latex gloves - preferably long ones.

Never EVER handle the stuff with bare hands or let it get on your skin.

ALWAYS add the stuff to water slowly.

NEVER, EVER pour water over the stuff - that way you'll have boiling strong alkali everywhere. Including delicate bits of your anatomy

Wear eye protection. I really mean this bit. I'd be blind many times over if I hadn't taken my own advice.

Caustic soda burns HURT. And take $£@%£$%^& ages to heal.

 

Make up a strong solution and stir well. Keep an eye on the temperature - it can get hot enough to boil the water and that causes Bad Things to happen. You really don't want it spitting boiling nasties at you. Believe me, I know! Do this outdoors or in a room/shed/bathroom you don't mind trashing.

Sodium hydroxide will also dissolve aluminium, so don't leave it in there too long.

 

The only nastier chemical burns come from strong nitric acid and one or two other horrible things you hopefully will never come across.

This guy is quite funny on the real nasties. At least I really enjoy it.

http://pipeline.corante.com/archives/things_i_wont_work_with/

 

It isn't actually that scary but it is a good idea to pay attention to the stuff or it'll bite you. 

 

The numbers from my light tests are always to be found here.

https://spreadsheets.google.com/ccc?key=0ApkFM37n_QnRdDU5MDNzOURjYllmZHI...

SPAMBOT
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Drain cleaner (lye) in powder form often contain mostly sodium hydroxide.

 

Sodium hydroxide removes the oxide layer on aluminum and the anodizing is basically a thick version of the natural oxide layer formed by aluminum when in contact with oxygen. Without it's protective oxide layer the aluminum will react freely with atmospheric oxygen and/or water in order to form a new natural oxide layer and bubbles of hydrogen gas. If the piece of aluminum still is in the lye solution then the oxide layer will get dissolved and more aluminum will be oxidized until the whole piece of aluminum is oxidized.

 

Be careful when you dissolve the drain cleaner powder in water since the reaction produces lots of heat and can make the water fizz, bubble and eventually boil.

Do not breathe the thin "mist" that can be produced when dissolving the lye and de-anodizing the aluminum!

Do not get it on your skin. It can cause severe burns and permanent loss of pigment.

A stronger solution is more hazardous, keep it as dilute as possible to minimize the risks.

If you spill the solution on something you want to keep clean it with lots of water and/or vinegar/acetic acid.

 

I'd basically just repeat what Don said, be careful with this stuff!

Now with 100% all natural asbestos!

charlestt
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Thanks guys i have most all of the above including protective gear in the shed so i'll have ago at this on the weekend.

 

Charles

 

 

 

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weiser
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YES! I'm resurrecting a thread more than 1.5 years old and I'm not even a spammer! A thread with a spelling mistake in the title to boot Laughing

 

Just wanted to report I've used drain cleaner in liquid form with success. Although, I probably leave it in too long and dissolve more than I should. I just go over it lightly with some steel wool and it's all off. I don't have much patience polishing intricate surfaces so I think I'll stick with simple flashlight bodies from now on. 

 

And I DID wear gloves and eye protection! PLEASE make sure YOU do as well! Smile

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This post is worthless without pictures, weiser. Wink

Just sayin'....

gcbryan
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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.

Don
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weiser701 wrote:

YES! I'm resurrecting a thread more than 1.5 years old and I'm not even a spammer! A thread with a spelling mistake in the title to boot Laughing

 

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

 

The numbers from my light tests are always to be found here.

https://spreadsheets.google.com/ccc?key=0ApkFM37n_QnRdDU5MDNzOURjYllmZHI...

Old-Lumens
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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

My PayPal address: oldlumens (insert the @ sign here) gmail.com

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Don
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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.

 

The numbers from my light tests are always to be found here.

https://spreadsheets.google.com/ccc?key=0ApkFM37n_QnRdDU5MDNzOURjYllmZHI...

dchomak
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DON

 

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!

http://www.dhmo.org/dihydrogen-monoxide/

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

Chicago X
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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)

http://wardogsmakingithome.org/index.html

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heyho
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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!

Chicago X
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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.

http://wardogsmakingithome.org/index.html

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Don
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heyho wrote:

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!

 

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.

 

The numbers from my light tests are always to be found here.

https://spreadsheets.google.com/ccc?key=0ApkFM37n_QnRdDU5MDNzOURjYllmZHI...

Don
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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.

 

The numbers from my light tests are always to be found here.

https://spreadsheets.google.com/ccc?key=0ApkFM37n_QnRdDU5MDNzOURjYllmZHI...

dchomak
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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."

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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.

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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.

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gcbryan wrote:
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.

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?

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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.

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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?