View Full Version : Have you done any home anodizing? Sulfuric Acid Source Question.

11-07-2004, 05:14 PM
I am about to fire up a small anodizing operation to anodize of bunch of motorcycle parts and jigs and fixtures that I have made over the years. A 3 1/2 gallon bucket system will meet my needs. I have most of the pieces and parts and dyes, sealers, electrical source, etc. required except for the sulfuric acid. I have found in my research that battery acid can be used. Anyone have experience using it verses buying reagent grade from a chmeical supply house.

If I was to buy it from a chemical supply house can you recommned the type, It's been 30 years since my college chemistry class and I am at a loss about the acid strength, normality, etc.. Guess I should have kept those old notes.

In advance, thanks for the assistance.

11-07-2004, 05:22 PM
It can be the weak electrolyte solution with a box added to One 5 gallon bucket.. give you the same results as the hi test and cost less too.

If the acid is too strong it will erode the anodize as it builds up.

I'll have to look on my notes for a Specific gravity to shoot for.. I use a old battery bulb to check it.

David Cofer, Of:
Tunnel Hill, North Georgia

11-07-2004, 05:57 PM
Sulphuric acid is used by plubers to clear toilets -so check out the plumbing section in your hardware store or go to a plumbing specialist.
why they use it i dont know as it will destroy everything below the toilet seat .
some one saw me use it on a toilet and went and got some for the sink drain- sulphuric and zinc fittings dont mix- got a call help
what do i do now there is a gallon of fuming sulphuric acid on the floor?

11-07-2004, 08:42 PM
Just about any auto parts house will cary battery electrolyte in a 16-32oz. "box". Always add acid to water. DO NOT add water to acid! The thermal reaction can blow it back in your face. Use distilled water too.

[This message has been edited by CCWKen (edited 11-07-2004).]

11-07-2004, 08:53 PM
For chemicals try http:\\al-chymist.com. Parkerizing, anodizing,bluing and blacking materials in non-commercial quantities.

11-07-2004, 08:54 PM
I used rainwater. Keep your chemicals seperate... Keep your washwater in between cycles.

Imagine, Soda is a alkali that reverses the PH of the acid to a neutral level.

WHen you get a acid burn throw a light alkaline (soda) on, when you get a Alkaline burn (Lye) throw a light acid (vinegar) on it.. Water on a alkaline sets it off. The water in the acid builds heat too.

Last time I got into some nasty stuff on my body, a valve malfunctioned and sprayed me with Sulfumic acid (powder reconstituted in to liquid) I looked down after being wet and my tennis shoes were bubbling as they melted into the concrete. I stripped right there and took a hose and started flushing. I was extremly lucky. One splash into your eyes and it can be all over and into a dark world for you...

I am the luckiest man alive. A old man once told me god takes care of the drunks and the fools.

Not reading, not knowing can get you hurt..

Crooks used to wash the safe deposit boxes with a Hot Hydrochloric acid, then hit them with a Cold lye, swing them metal back and forth till it crumbled under the stress.. and the Stainless vault would just fall out on the sidewalk. You probably don't need to know that thou.

Beware.. Splashes, Heat bubbles.. and mixing chemicals you don't know what they will do..
Explosions result.. I heard of toilet bowl cleaners mixed with Sodium Hypochlorite (bleach) blowing the wall out and producing a toxic gas where one whiff is enough..

Read, study, learn before you do... and regret.

David Cofer, Of:
Tunnel Hill, North Georgia

11-07-2004, 09:00 PM
The specific gravity of sulphuric acid that
auto supply houses have is 1300.
The reference of pouring acid into water is very important. Never pour water into acid.

11-07-2004, 09:07 PM
I should say one more thing regarding the specific gravity of sulphuric acid obtained
from auto supply houses. It varies in specific gravity depending on how far you are from the equator.It is a weaker solution down there and much stronger in Alaska. If they used a stronger solution in hot climates the batteries would not last very long at all.

11-07-2004, 09:09 PM
Dave's annodizing instructions on my website:
web page (http://thisoldshed.tripod.com/annodizing.htm)

(Yes Dave, I finally got around to putting it up.)


[This message has been edited by HTRN (edited 11-07-2004).]

11-07-2004, 09:24 PM
OK, you mentioned college in your post. I have found that the best source for chemicals like Sulphuric acid is a college chemistry department. They have some sales out of these places, and may also tell you the mixtures and how to do it. My father used to home anodize and Black Oxide (before this process became illegal), and we went to our local college for chemicals because of the knowledg, an the cost being cut rate.

As for water mix. I use a Brita filter to purify my water. This filter bases its action on "deionization", which produces incredibly pure water. My father, an electorplater, an later a waste water manager (because he had to become one because of chemical disposal) swears by these filters. He uses de-ionizers of a larger scale to this day to purify his water in his hot tub (he is retired now, thus has the time to fool with this and play with this water, and it is so clean....). Rain water in some areas of the country are highly acidic, such as in my area at times.

The other sources listed are also quite good. Just putting my two cents in.

How are you doing chemical disposal? You really want to be careful with this aspect of your job.

charlie coghill
11-07-2004, 10:45 PM
As stated above pour the acid into the water but pour it slowly. Too much acid at one time heats the water and can cause problems.

11-07-2004, 11:19 PM

I get MSN homepage on that link.. Now ain't that just like tripod..


11-07-2004, 11:42 PM
Battery acid is available at any auto parts store. I did have to buy 25 liters which should last me until 2999. Yes on the caution not to add water to acid.

As far as disposing of used anodizing solution use soda, sodium bicarbonate, to neutralize the acid bath. Add it slowly, when it stops fizzing at all then it is neutral. You can dump it on the ground. There are no hazardous materials in it. The process makes aluminum sulphate in the acid bath which is a fertilizer.

11-08-2004, 12:58 AM
Dave, my fault(typo) try it now.


11-08-2004, 01:03 AM
I buy my acids from Ashland Chemical, most of the times I get 2 litres. They will tell you the percentage of the solution, which is slightly above what normally I use in gun smith electroless ncikling, so I buy a bottle of distalled water and cafefully decant some acid in a jar with water until I get the right mix.

This is rocket science, but it is damgerous.


11-08-2004, 09:01 AM
I use battery acid from the local auto parts store added to an equal amount of distilled water. It works better that I ever expected!