Home anodizing issues

[kielbasavw]

So I'm trying to anodize a part. And having some issues.

I have a bucket mixed with a gallon distilled water and 25oz sulfuric acid I have my part hanging with 3/32 stainless wire. I have a piece 3x2 aluminum square tube for the negative.
Here is my problem
I've tried several different power supplies. 2 battery chargers and a 12v battery. They all give too much amps. I can set my charger to 12v 2amp and the machine reads 50 amps! Things get hot and acid solution turns yellow.

I currently have a small 12v charger that charges at 4 amps. It will peg the dial for a couple seconds and shut off for about 5-10 seconds and turn itself back on.

If I hook that same charger up to a battery it will read a constant 4 amps.

What gives?

[craneman]

You need to use aluminum wire or titanium wire. No steel in the bath. Are the wires hooked up right? cathode is neg., anode is pos. nothing should touch together. It sounds like they are and you are getting a dead short, or it is a problem with having steel wire in the bath.

I mix mine with 1 quart of electrolylte to 1 gallon of distilled water.

Are you using distilled water?

[pacrat]

Deleted, Craneman got it covered.

[kielbasavw]

I've read stainless was okay. You can even anodize stainless as well.

Parts definitely aren't touching. PositI've on lower. Negative on aluminum scrap piece

Yes using distilled water

[craneman]

Are you using premix battery acid (electrolyte), or lab grade sulphuric acid? The mix should be 12-15% acid to water by weight. I just use battery acid and mix to the measurements I listed above, and works great every time. The charger that keeps shutting off is tripping the breaker. That type will not work.

2A setting. Mine never gets above 4 amps on the meter.

[craneman]

I have never heard that. I could easily be wrong, but I know what has worked for me many times before.

[kielbasavw]

Well I switched to aluminum wire. The wire I have breaks if bet too much so getting it to stay afloat is tricky. With the aluminum wire the charger at 2a now reads 10amp on the machine.

I'm using sulfuric acid that's listed as a drain cleaner. It's 93% acid 7% water

[God Bless America]

That's concentrated sulfuric acid

[pacrat]

Chargers are designed to "supply" whatever amp load the battery requires. Due to the type of chargers you have, they are supplying to many amps for the process required.

Suggest you try wiring a potentiometer in series with the + anode. Potentiometer is just tech term for a dimmer swith or volume control. Just a variable resistor.

Then you could control the load the charger puts out.

Just a thought. Know very little of anodizing, but some regarding electrical controls.

[craneman]

Well I switched to aluminum wire. The wire I have breaks if bet too much so getting it to stay afloat is tricky. With the aluminum wire the charger at 2a now reads 10amp on the machine.

I'm using sulfuric acid that's listed as a drain cleaner. It's 93% acid 7% water

Sorry I had to bail on you, I had a previous appt.

25oz acid to a gallon of water is too hot. You need to add another gallon of distilled water. You are shooting for 12%- 15% acid to water by weight. 128 oz to a gallon. You need roughly 14 Oz of acid per gallon. That's if you are still using the drain cleaner, and I am not so sure what else might be in there. I've never tried that stuff.

Also, keep in mind you should have at least an equal size (surface area) cathode as the part you are anodizing. Bigger is always OK, but smaller is not as efficient. It also needs to be on at least 2 sides of the part. exposure of surface area and time are how you time it so you know when to stop. If you are using aluminum instead of lead sheet for the cathode, I have found 6061 alloy works the best for me.

Pacrat is right, you need a constant voltage power supply. A cheap battery charger that does not have circuit protection will work, but it is not adjustable so the variables have to be closer to ideal for it to do a good job.

Hope this helps.

[Capt.Dunsel]

Have you tried an old computer power supply instead of the charger ?

I use one for copper/gold/silver plating cast bullets .

You can get just about any voltage , by adding a resistor to the positive power line you can get the exact amps you need / want .

If you don't have a spare you can check thrift / second hand stores . They run under 5 bucks most of the time .

[kielbasavw]

Well I got it to work with the 10 amps for about an hour. It took the dye. One side ended up a lot darker, other side a bit lighter and splotchy. I think it's good enough. Especially with parts that don't match eachother anyways