% Sulfuric in Battery Acid?

[jime]

I bought battery acid at an auto parts store to anodise with and the salesman said is was 100% sulfuric acid. It worked well at 50%. I bought some more later that was MUCH cheaper for a larger quantity at another store that didn't work so hot at 50%. Is it possible that it was diluted? Does anyone know what the dilution rate is for battery acid? Is there a better source for sulfuric?

[jime]

Should have...

...read other posts on the subject before, as it seems they answered most of my questions! Looks like i should use straight 'battery acid' and not dilute it. Is there a way to test the ratio in the solution?

[mcaswell]

You can test the specific gravity of the solution with a Hydrometer.

http://www.freasglass.com/battery.htm

[mcaswell]

Buy Battery Acid from NAPA Auto Stores, product # 9002. It is a consistantly high quality product.
Specific gravity = 1.26
Pure sulfuric acid (reagent grade) is 98%
Battery acid is 1 part reagent grade to 2 parts distilled water.

Our instructions call for BATTERY ACID, which then has to be diluted.

The reason for this is that reagent grade is very difficult for the amateur plater to find, whereas battery acid is easy.