Seeking Chemicals for Anodizing.

Aluminum How-To
"Chromating - Anodizing - Hardcoating"
by Robert Probert

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"The Surface
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Aluminium and
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by Wernick, Pinner
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A. Flattery of our site may not get you too far, but it usually at least gets you a response from me

Anodizing is an electrochemical process, so it's not just a matter of the chemicals, you need the fixturing, power supply, etc.

The least expensive way is to see if you can find a jobshop that will do this for you. Anodizing, like plating, tends to be done on a service basis, so there are usually shops that serve the public.

The chemical required for anodizing per se is simply sulfuric acid, which is readily available. But you probably have to clean the parts first and perhaps etch them in caustic soda ⇦liquid caustic soda in bulk on Amazon [affil link] to a slightly matte finish to minimize fingerprinting. Unless the aluminum is very high purity, etching will leave copper behind, which will turn the surface black, and will require a desmutting chemical (nitric acid may suffice). Then you put the parts in a vat of 10 percent sulfuric acid, at perhaps 12 volts for maybe 15 minutes. Then you seal them in boiling water for at least as long as the anodizing time.

Hopefully you have a lab instructor who can help you do all this safely.

Please post a photo of your work if you meet with success!

It appears the flattery may have gone to Ted's head ... as he left out several important things in his reply, i.e., heating, cooling, rinsing, agitation, dying, etc. For about $30-$40 US, I'm sure you could have a qualified anodizer coat your parts, and I'm sure your results would be much better ... especially if this is a "one time shot".

Marc, you are absolutely right that it's not easy. I said: "The least expensive way is to see if you can find a jobshop that will do this for you."

I constantly remind people that anodizing and plating are not a good hobby, and they should leave it to professionals. But we're speaking to a 4th year art student, studying in Germany, working on a sculpture. I've rarely known any artist to contract out their painting, welding, molding, plastering, machining, patinization, or anything else--and I'm just entertaining the possibility that this is art to be created by the artist, not assembled from factory parts.

But thanks for reinforcing that anodizing isn't easy, and including some of the requirements I had omitted!

Yeah.. I realized that..right AFTER I hit the submit button...besides...I was just havin a little bit of fun with ya anyways

Just remember that you told Charlotte she could build her own anodizing installation complete with heating, cooling, rinsing, agitation, dying for $30-$40 US. I remember it clearly, don't go telling me I got all lightheaded and confused.

oops... I guess I did leave out one important cost factor...the racking to hold the parts...that should cost about..say..$75,000 US...soooooo, the total cost (with racking), ought to be around $75,040 US, or you could find a qualified job shop to do the work for you. Thanks for correcting my obvious mistake, Ted, would sure hate to lead the nice lady astray. :)

!! $75,000? How about $200.00 and you've got a toy for life. It will also do titanium vanadium an niobium. Buy a 10 amp variac, a bridge rectifier, a $5 plastic aquarium from the pet store, trisodium phosphate ⇦this on eBay or Amazon [affil links] , distilled water, a couple of wires with alligator clips and anodize your head off for next to nothing, $75,000.00 ? it takes two seconds to wire it, good luck.

---

Happy to agree that you can anodize titanium with such a setup, Chard. You can't anodize aluminum in TSP, however.

Ted Mooney, P.E.
Striving to live Aloha
finishing.com - Pine Beach, New Jersey
2007

I don't know how anyone "makes a small fortune" without selling their product though, Martin. Here in the USA you are immediately subject to EPA 40CFR433 and a host of other very expensive mandates if you sell anodizing services or anodized products. I know a person who served penitentiary time because he let his personal plating hobby in his garage grow into a small business, and then he couldn't get out from under the waste liability without losing his house; he got caught dumping. If you think this can't happen, tell a neighbor that you are anodizing in your garage or basement and watch what happens when his toilet backs up and he starts making calls to the town. Remember that in the USA if you are running an anodizing service it is illegal to dump even the cleanest, totally neutralized rinse water down your drain because every drop of rinse water and hose water is categorically regulated (although I realize that you won't necessarily get caught and that the authorities are usually more interested in bigger fish).

Anodize as a hobby if you wish, or go into the anodizing business if you wish, but in the USA plating and anodizing shops were the EPA's very first regulated businesses -- so be careful about letting your hobby grow into a business without an actual plan.

A. Hi.
You can add sulfuric acid to your anodizing tank, Mistie. The question is ... how much? For decorative anodizing, sulfuric acid should be maintained at 180~220 g/l and aluminium content at 5~15 g/l .
For black, you need a thicker oxide coating to get the deep jet black look.
Current density around 1.5 A/dm sq. at Constant current for 45 mins will get you there. Good luck.

I used to do those adds when I worked for Anacote, for that grand old gent of anodizing, Frank Kraft. I don't think I've ever worked for a company so devoted to excellence.

Anyway, make sure not to add the acid while there are parts in the tank. And, allow the electrolyte to come back down in temperature after the addition. Failure to do so is apt to cause problems.