Acid Bath Content?

[Chevalier]

I am having trouble getting certain parts to anodize, some will work but others won't. The acid bath is 10% sulphuric acid with 30g of Sodium sulphate per litre of sulphuric/water solution. I read this off a webpage of a guy who does anodizing with good results, but I have yet to see this mix mentioned since! Does anyone know the reason for the sodium sulphate and could it be causing my problems? I have tried using a 12V charger and also 2 car batteries(ie. to give 24V)the batteries make short work of burning the parts!
Should I make a new acid mix(with just sulphuric acid) and try it with the charger again? I am going to get a light dimmer tomorrow and try keeping a constant current, but I am still limited to 12V.
Any help would be great.
Thanks

[NeoMoses]

I have never heard of using sodium sulphate in your electrolyte solution. Although this may have a place, I know for a fact you can produce good results without using it.

I would recommend making a new bath and trying out the LCD method of anodizing. It has produced very consistent results for me.

[Chevalier]

Thanks, I originally bought a bottle of sulphuric acid to do the anodizing, so am I correct in thinking that you are using 5% sulphuric acid, so when I mix it I want to add 1 part acid to 20 parts water? do you also think that 12 volts will be sufficient? I am having serious problems finding a sufficient power supply here(Ireland), so I'm trying to get it working with what I have got!

Many Thanks

[Fibergeek]

Chevalier,

Battery acid is 19.17% concentration by volume. Mix 1 part of this with 3 parts distilled water. This results in a concentration that is 4.8% (5%) by volume, which is correct for LCD.

PM Whistule, who is in Scotland. He can probably give you UK valid advice about a power supply.

I've also read about sodium sulfate in the electrolyte, I'm not clear on what it's supposed to do.