WTT - Anybody know about chemical anodizing?

[billw]

I have a project that's non-whistle, involving aluminum rings, but thought it could just as easily apply to my whistles. There's an outfit that makes colored aluminum rings for armor. They state that they're "anodized" which implies to me they don't scratch easily. The difference I've seen between what they do and what I do, is that the ends of the rings don't show any bare aluminum. Given their diameter (3/8 inch) and the quantity of them, I doubt they connect each one to the power source to do the anodizing. I must assume there's another process that allows them to get the durn things evenly coated, without having to tediously hook up each one.

Does anyone have info on this process?

Thanks,
Bill Whedon

[Rockymtnpiper]

You might try stretching the chain out tight. As long as there is contact/ an electrical circuit ... it should work. This is the only way I can think of that they might use and be efficient on the time spent.

OTOH.. I know a few things about REMOVING anodization. I have had the misfortune of Doing this, that and the other on a spec house.. Its in the "nuvou skanky" acrchitectual style. Everything is done in flambouyant earth tones, and rust everwhere.. a pleasing rust finish even. Muratic acid dabbed on carefully with a paint brush will remove the anodizing/protective coatings on many types of metal, and fasteners leaving a pleasing rust finish.

[pizak]

I've made a couple of Aluminium whistles, and I looked upi anodizing on the Internet. I found an amazingly detailed guide on doing it at home, which was great, but you still need high voltage and sulphuric acid.... hmmm maybe not for me.

Anyway, to cut a long story short, I phoned up a local firm from the yellow pages, and they do it for me.... I hand them a tenner a go - because the unit cost is about 90p each for a hundred! but I'm just getting a couple or three done at a time.

Paul

PS. the finish is very hard wearing, but not as beautiful as when the aluminium is recently shined and polished. They do look cool. My wife calls my high D the luger, because it comes apart and with the brushed matt metal look from the anodisation it reminds her of those films where the baddies assemble the gun once they've got thru security.... i think im rambling now....

[billw]

Thanks for the replies... the anodizing I do uses a 12-volt battery charger outputting 15 amps in "manual" mode, and I use a 12% solution of sulfuric acid as the anodizing bath. I run the process for about 70 minutes, on average, until the current levels out.

I guess restating the problem might help -- what I want to do is to make the rings first, then put a positive charge on them without directly hooking them up to the power supply. Barring that as a possibility, there must be some other (electro)chemical process that's used commercially/industrially, that has the same effect. That's the process I'm looking for.

I can make the rings easily enough by doing the coil first, stretching it, then anodizing the whole thing. But when I clip the links from the coil, the ends aren't completely coated. It's a "looks" thing...

Re. high-voltages ... yes, if you want to do "hard anodizing", then you do need to work with voltages higher than 12VDC, but the most common process does leave a good, hard coating on the aluminum, and is easier to color in post-process.

Anybody got other ideas?
Cheers!
Bill Whedon
Serpent Music

[OutOfBreath]

You might try alodining - it's a purely chemical process. It's not as hard a finish and I don't think you can dye it, as far as I kinow your finishe colors are limited to silver and gold. Also, if you want to paint aluminum alodining forms a good base for paint. Alodining also provides very good corrosion protection - it's used quite a bit in the aircraft industry and by experimental aviation buffs because you can do very large pieces pretty economically.