Ghetto aluminum anodizing

Projects other than metal casting.
Lambda_drive
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Joined: Tue Jun 07, 2011 7:59 am

Ghetto aluminum anodizing

Post by Lambda_drive »

I'm planning on anodizing a few small parts at home, but the problem I'm having is finding the chemicals for anodizing aluminum. You need a dilute Sulfuric acid solution(battery acid) and Sodium hydroxide(Lye). The funny thing about those two chemicals is that they're both used in Meth labs and for making explosives so it's really hard to find them in stores. I was wondering if you could use a substitute for those two chemicals. Sodium hydroxide has a pH level of 14 So it's a really strong base. Ammonia is a really strong base too, but it's pH is only 11. So it's not quite as strong as lye, but it should still be able to etch aluminum oxide. Finding a substitute for Sulfuric acid is kind of hard because it's pH level is about 0.8, Lemon juice has a pH of 2.4. I think it might work, but it'll probably just take a long time.

I know I can buy those two chemicals online, or just find a place that does anodizing. But what's the fun in that. I just want to see if you can actually anodize aluminum with things you can find around the house.
Rocco
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Joined: Thu Jun 02, 2011 8:35 am

Re: Ghetto aluminum anodizing

Post by Rocco »

If you happen to have a friend that's an auto mechanic, have him get some battery acid for you, he can get it no questions asked, it's cheap too I think I paid $12 for 20L. Normal battery acid needs to be cut with equal quantities of distilled water. You don't need sodium hydroxide unless you want to strip off an existing anodized coating.
wikisi
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Joined: Mon May 30, 2011 7:54 am

Re: Ghetto aluminum anodizing

Post by wikisi »

Sulfuric acid isn't hard to find. It's sold as drain cleaner. The brand I get is called Liquid Fire which seems to be pretty common. It's about 93% sulfuric acid from what I've read. If you can't find that brand, in the drain cleaners isle look for plastic bottles that come in thick plastic bags, these are usually the sulfuric acid based drain cleaners.

As for Lye, I just walked past it this afternoon at my local Ace hardware :roll:

Whenever I buy these things, I don't get any weird looks or ask me questions as to what I plan to do with these chemicals so I think you should be OK.
Rocco
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Joined: Thu Jun 02, 2011 8:35 am

Re: Ghetto aluminum anodizing

Post by Rocco »

You need to be careful with acid based drain cleaners, they often have other ingredients in them that may have a negative impact on the anodizing process, fresh battery acid on the other hand is just sulfuric acid and water plus, I doubt you could beat the price.

But you're right about the lye, it's a standard hardware store item. BTW, it too is often sold as drain cleaner.

This sort of goes without saying but both of these chemicals can be rather dangerous if handled incorrectly, a very healthy dose of care and common sense is called for, make sure everyone in your work area understands this.
davidbraley
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Joined: Sun May 29, 2011 6:13 pm
Location: Fort Collins, Colorado

Re: Ghetto aluminum anodizing

Post by davidbraley »

I have a small anodizing setup here at home. I've been offering it for small jobs and my own projects for a couple of years now. I just buy my battery acid over at my local NAPA autoparts store. I buy it by the box, three gallons I think is the size. I buy my lye from Ace Hardware. The brand of lye is called Red Devil. I have never had troubles finding both chemicals locally. My color dyes and sealers I get from Caswel.

Here are some pictures of some custom caster camber plates of my own design that I build myself here in my home shop. I anodize in red, blue, black, and clear (no color step).

Red:

Image


Blue:

Image


Black:

Image


And Clear (no dye step):

Image


Hope that helps.

David
-David

I cut it off three times! And it's still too short!
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Harry
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Re: Ghetto aluminum anodizing

Post by Harry »

That is an awesome piece David. I am guessing these are machined from billet stock like 6061 or some other wrought aluminum? Those colors are stunning.

This is one thing that as I understand it makes a difference in anodizing between extruded or wrought alloys and casting alloys. The addition of silicon hampers anodizing. This is of course just my understanding from reading and I would love to hear more on this from folks who know.

Anyone care to do an anodizing writeup along with pictures?
I'd rather laugh with the sinners than cry with the saints the sinners are much more fun...
Muller
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Nudge
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Joined: Sun Jun 05, 2011 6:18 pm
Location: Auckland, New Zealand

Re: Ghetto aluminum anodizing

Post by Nudge »

Man they look real nice 8-)
Do you have a pic of the setup that you use?
I like to build "Stuff" using Stuff that costs Stuff All!
wikisi
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Joined: Mon May 30, 2011 7:54 am

Re: Ghetto aluminum anodizing

Post by wikisi »

Oh wow, these look great!

I second the writeup idea 8-)
Wayne
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Joined: Tue May 31, 2011 10:27 pm
Location: Charlotte, NC

Re: Ghetto aluminum anodizing

Post by Wayne »

Those are really nice David! What car are they for??

Wayne
wikisi
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Joined: Mon May 30, 2011 7:54 am

Re: Ghetto aluminum anodizing

Post by wikisi »

Cool link on anodizing aluminum

http://www.focuser.com/anodize.html
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