# How to anodize aluminum?



## RGBrainbow (Mar 23, 2004)

Hi people,
does anyone know how to anodize aluminum (colored) as a hobbyist ?
regards
joachim


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## unnerv (Mar 23, 2004)

I would check out Caswell plating. I have heard that their kit does a pretty good job for hobby type plating.


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## SKYWLKR (Mar 23, 2004)

That was going to be My next post...thanks.

I am going to Gold Plate my next light as I have access to that equipment and chemicals... but I wanted to Anodize for a tougher finish.


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## Doug S (Mar 23, 2004)

Chief Wiggum had a very good post on the subject awhile back. Unfortunately the board search function sucks bad. You may find it faster by looking just at Chief Wiggum's posts for a subject like DIY Anodize.


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## Chief_Wiggum (Mar 23, 2004)

I suppose I should post a HOWTO article on this. The next time I have my setup out, I'll take pictures.

Basically, it goes like this for my simple home setup:

- degrease with Simple Green.
- repeat
- repeat
- attach the part with aluminum wire to the + side of my constant current power supply.
- immerse some more aluminum wire in a sulphuric acid/distilled water bath. Mixed 50/50 battery acid distilled water
- attach - wire of power supply to this wire
- immerse the part in the acid and turn on the power supply.
- set current to anodize at 3.5A/ft^2
- observe voltage. It will peak then begin to taper off. Stop anodizing after the peak.
- remove part and rinse in COLD distilled water
- dye at 130 degrees for 15 minutes
- drop in boiling water to seal
- wipe with mineral oil
- admire your work /ubbthreads/images/graemlins/grin.gif

There some more stuff I left out, but that's the basics. More to follow as soon as I get around to it.

Just be aware that the acid and it's fumes are very dangerous even though the acid has been reduced in concentration. You absolutely NEED goggles long gloves. No exceptions. It's also highly advisable to work in a ventilated area avay from open flame.

I use Caswell's dyes. They're fairly inexpensive and work better than fabric dye.


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## cy (Mar 23, 2004)

No need for distilled water for the rinse. Tap water will work fine. I've never dyed with a heated solution, all my dying were at room temp. Always follow mfg recommendations. 

We used Trichloroethylene vapors for degreasing. That's probably not allowed anymore. On particular dirty parts we used a caustic hot bath to degrease, but you really had to watch it. Aluminum is very reactive to caustic agents. Aluminum parts that needed to be activated were dipped into very strong nitric acid. The really nastic stuff is nitric/hdrofloric acid. We used to mix that stuff up, a deep orange smoke would come off of that. Very scary stuff!!!

A major consideration is anything in the imediate vacinity will be etched by the acid fumes. That's why I will not setup to do color and/or hard anodizing at home/garage. Too much liability from the acid fumes. All my tooling/vehicles in the garage will end up with a layer of rust. If you have separate workshed with drain to isolate the fumes, then that would OK. 

Edit: If you have the time, visit a plating shop. Note that everything metal in the shop will have some degree of corosion. A light to heavy layer of rust will be on almost everything in the shop, including the structural beams if any.

Note: Please use extra care when handling 99% reagent grade acids, used to delute to % needed. I would alway use gloves and safety glasses handling reagent grade acids. 

Avoid the wearing cotton clothing when working with acids. You will end up with holes from small splashes.


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## KC2IXE (Mar 23, 2004)

Look Here


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## OZ (Mar 23, 2004)

KC2IXE
Wow..... that was awesome! /ubbthreads/images/graemlins/thumbsup.gif


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## darkzero (Mar 24, 2004)

Yes the link KC2IXE posted is awsome. I came across the same site a while back before he updated it with being able to purchase dyes from him. Excellent info. Still haven't tried it though, have you KC2IXE?


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## KC2IXE (Mar 24, 2004)

Nope, I haven't tried it - I really haven't had the need. To be totally honest, my shop time has been lame for 2 years. I've done about 3-4 hours of work for ME (in 2 years) - the rest has been spent running brass parts for a client - and that's a few hours/month. One day soon, I'll REALLY get back to working down there - I have some (most?) of the castings for a Live Steam engine down there


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## Psychomodo (Mar 24, 2004)

[ QUOTE ]
*SKYWLKR said:*
I am going to Gold Plate my next light as I have access to that equipment and chemicals... 

[/ QUOTE ]

How do you do that? /ubbthreads/images/graemlins/thinking.gif

Colin


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## Chief_Wiggum (Mar 24, 2004)

Check Caswell's plating. They have gold plating kits.


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## SKYWLKR (Mar 24, 2004)

very similar process cept a bit nastier chemical and you need a Gold bearing soulution /anode.


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## SKYWLKR (Mar 24, 2004)

My dad built a gold Plating pin out of a Q-tip and a AC/DC wall convertor a few years ago. I might try to dig that up, to make things simple.


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## RGBrainbow (Mar 24, 2004)

Hi people,
thanx a lot for this load of information.
I'll show You the results.
regards
joachim


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## Psychomodo (Mar 26, 2004)

[ QUOTE ]
*Chief_Wiggum said:*
Check Caswell's plating. They have gold plating kits. 

[/ QUOTE ]

Thanks /ubbthreads/images/graemlins/wink.gif


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## cy (Mar 26, 2004)

I hate to be the bearer of warnings /ubbthreads/images/graemlins/icon15.gif, but be advised: 

Handling concentrated Sulfuric acid can be dangerous, but with the proper gloves and glasses with no problems. Disposal is simple, delute and flush. (check you local ordinances) 

Plating chemicals opens up a whole another can of worms. 
Chemicals involved can be hazardous to your health. Think of disposal before purchasing. You may not be able to delute and flush. Plating solutions are commonly loaded with heavy metals and possibly cynides./ubbthreads/images/graemlins/crazy.gif /ubbthreads/images/graemlins/frown.gif


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## SKYWLKR (Mar 26, 2004)

Yep very bad stuff.... gold and sivlver plating is extra nasty


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## HarryN (Apr 22, 2004)

I have heard that it is harder to get a uniform anodize on 7xxx series than 6061. Is that correct ?


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## Chief_Wiggum (Apr 23, 2004)

I've had good experience with both, no problems with either.


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