The Stovebolt Site Forums The Shop Area Paint and Body Shop electrolysis: what's going on?

Using the tech tip for de-rusting metal I have an old wheel cooking. Everything is hooked up right, double checked, positive to electrode, negative to work, in washing powder solution, 20 amps rectified through a 12 volt battery. After several days the wheel is covered in crud that is hard to scrape off and the electrode is clean as a whistle, the reverse of what I expected. What is going on here?

the process takes hours, not days - does not require high amperage, a 'trickle charge' rate does fine - the electrode will not get dirty, but will over time be eaten away - did you use washing soda/sodium carbonate? about 1 Tbsp per gallon of solution? - are you expecting grease and paint to be stripped? the process works on actual rust only the 'crud' may be an ever thickening layer of converted iron oxide, it should be black, the color will not come off, but "flakey" corrosion will need to be chipped off

here's a sequence: manifold w/ lite rust .... using a funky antique charger that supplies about 2 amps, after about an hour, bubbles caused by current flow .... after a few hours, note the water is dirtier and rust colored ... manifold pulled out next morning [about 12-15 hours total], after fresh water rinse - note the rusty areas have turned black, the rest is unaffected .... and after brass wire brushing

Bill

I just used this process on several of my parts. The electrodes were always covered with a build-up of crud.
Did you make sure the part was not touching the electrode?
Did you suspend the part in the solution?

....I tried it guys but I'm just not impressed. I guess I'm spoiled by having a sand blaster. I did a set of 454 exhaust manifolds Saturday night. Took me an hour. Rub some calyx on them and they were ready to go.
I'm probably doing something wrong but it just don't do anything for me.
When I tried it I never got the results I was looking for and still had to "scrub a dub dub" and still not satisfied.

I guess I'm spoiled by using a Phosphoric acid bath. That manifold would have looked bright and shinny new after a couple of hours in the bath.

Gonna try the electolysis this summer soon as the weather breaks
but I'm not expecting to much.

DG

I have used the electolysis with mixed results. First try I was impressed. Last time, not so much. The second time I used a big tube with reinforcing mesh surrounding the inside of the tub. hung the metal in the center suspended by a wooden dowel. Not much foaming action.
The first time was with a small bucket. Worked well on small parts.

I have also tried the molasses (agricultural grade) method and it worked well too. Just takes longer.

Denny I have never tried phosphoric acid. What is your process and what do you do with it once you have finished with it? My molasses you can put on the compost pile. Although I haven't yet.

I buy it in gallons at the big box store. Only product available now is Kleen-Strip Prep & Etch. I soak,
rinse dry right away and paint. The acid leaves the metal ready to paint and is the active ingredient in
metal conditioners sold by PPG, DuPont and others.
You never finish with it. It can be used over and over till it gets to contaminated to use. I have yet to
figure out what I'd do with it if I wanted to dispose of it. Getting rid of acid seems to be one of those
things that no one will talk about or else no one really knows what to do with it. I've got several kits still
boxed up from Caswell Plating and haven’t used them because there is no means for disposing of the
chemicals. The only response I’ve gotten about the plating chemicals is “Dispose of properly at your
local hazardous waste site.” What they don’t say is that a hazardous waste container will cost you
$500. As far as disposing of the acid I think there are ways to neutralize the acid but since I’m not a
chemist I don’t have a clue and when it‘s neutralized what can I do with that waste?????. When I crook
and they have the auction I wouldn’t doubt that the auction guys will just pour it in the ditch so they can
sell the containers.
Denny Graham
Sandwich, IL

huh - bright shiney cast iron Denny?? get some pictures the next time you achieve that with phosphoric acid I use metal prep [phosphoric acid] as a neutralizing cleaning wipe like it's most commonly used, then you don't have to worry about disposal .... and like with electrolysis, I find using the acid results in the red iron oxide being converted [it is called a rust converter] to black iron phosphate, doesn't do much otherwise

there's no disposal problem with sodium carbonate, it's a common water softener [why it's used in laundry] and pH controller, commonly used in swimming pools, also commonly used for boiler de-scaling, one of the most common chemicals around, even used in food processes ..... which thought makes me wonder if you folks that have poor or mixed results have "hard water"? maybe the effects of the soda are being "neutralized" by other minerals native to the water in your locale, which may explain erratic results, some variation in the mineral content of your water over time

the reason I use this technique is primarily because I happen to have 50# bags of the stuff on hand - years ago I researched what additives to use in the antique commercial bottle washing machine I found for my business, for over 20 years it's been the sole additive, to avoid any scale buildup and act as a surfactant - works a treat .... so some of you might want to give it another try using distilled water OR boiling the water used first OR double up on the soda

Bill

Well since you doubt or question about every thing I post Bill, I went out and threw an old
rusty cast iron exhaust manifold I had laying around in the phosphoric tank. I’ll pull it out
and post some pix tomorrow or Saturday. And no a rust pocked 60 year old cast iron
exhaust manifold is not going to come out bright and shinny, but it will come out as clean
as it can possibly be for something in that shape. If the part is simply the victim of mild
rust it will come out looking dang near new, mind you I said dang near new not new so
please don’t quote me as saying it will look like brand new polished metal.

Here is a batch of parts that were dipped before they were sent out to be cad plated. The
radio covers were quite heavily rusted and the original sacrificial plating was nearly all
used up. The long bracket was in the same shape and the sheet stock for the speaker
brackets had surface rust from being stored for a couple of decades. The stacked brackets
were made new but the blanks were also dipped to clean them of any mill scale or minor
surface rust that was on the bar stock before forming. The thin yellowish/brown film that
you see on some of the parts is the phosphate coating (conversion coating) which can be
painted over but in this case it will be removed when it is submerged in the plating
solution. http://www.pbase.com/dennygraham/image/133951157

Here is the fan from my ‘54 before it went into the bath;
http://www.pbase.com/dennygraham/image/131017629
Here’s the fan as it looked right after it was rinsed in cold water and before it was touched
up with a fine wire brush;
http://www.pbase.com/dennygraham/image/131017617
Here’s the finished piece ready to be installed;
http://www.pbase.com/dennygraham/image/131015821

Another piece of the drive shaft before;
http://www.pbase.com/dennygraham/image/131015814
Right out of the bath and rinsed;
http://www.pbase.com/dennygraham/image/131015810
And after lightly brushing on the fine wire brush;
http://www.pbase.com/dennygraham/image/131015805
The finished yoke ready to install;
http://www.pbase.com/dennygraham/image/131015804

Denny Graham
Sandwich, IL

not doubting Denny, just a healthy skepticism of you saying "That manifold would have looked bright and shinny new" when new cast iron parts look pretty much dull flat black, as does the manifold I cleaned, except where polishing off the iron phosphate left it gloss black .... but the primary point here is that electrolytic de-rusting does work well, and consistently so, with the correct parameters, and in response to Matt finding "the wheel is covered in crud that is hard to scrape off", the converted rust will need brushing/scrapping if it was heavy, and the layer in contact with good metal won't "scrape off" ..... and the process doesn't involve 'hazardous material' disposal problems

Bill

Bill & Wayne, Thanks for the reply. I did use washing soda. I have used this process before with the exact same setup with satifactory results on a much smaller and less rusted piece. I can use a lower amperage but read somewhere that 10-15 amp was ok. The wheel has no grease or paint on it. Must it be suspended or can it lay flat on the bottom of the plastic pool? The electrode was not touching the work.
Is my electrode, a 1 inch square tube, big enough? (no comments from the peanut gellery, please :-) Do I need more or bigger electrodes? Matt

Matthew,
Remember unlike acid baths or the rust removing gels and liquids, electrolysis is line of sight. So did you have the wheel surrounded by the sacrificial metal? You would get more action I believe. Someone correct me if I am wrong. Haven't used the method that much.

Matt, I used a piece of 16 gauge hardware cloth, (1/2" wire mesh) bent into a U shape, down the side of the plastic pail, across the bottom and back up the other side. The parts were suspended between this and the system worked well.

Bill you missed the point about possible conflict with epoxy primers and a failed paint job down the road if the acid isn't properly treated...

As to the wire mesh surrounding the work I think the idea is good but the quality of metal your trying to exchange may be a source of concern, if it were diamond plate you might see better results. The sacrificial metal needs to be worth sacrificing

My experience with it was positive except for all the cleaning I still had to do when it came out of the bath.... but at least I wasn't worried about my paint falling off and the cleaning didn't take any longer than blasting it from scratch would of.
I can see the blast cab as being of benefit time wise but 'no cab' would leave a bigger mess to clean than the sink area I mess up now.
It's a crappy job no matter which route you go from where I sit.

I agree w/ Paul and Leo, the anode needs to be large, the action is "line of sight", a piece of sheet metal bent in a circle to surround the part is ideal .... the wheel laying on the bottom is OK, but the underside won't be much affected so you'll need to flip it over for another session to clean the "hidden" surfaces, I'd stand it on the beads and rotate it a few times over a day or 2 - with some parts it's best to pull it out and brush it off some and put it back in a different orientation, all surfaces don't need to be clean at one time .... and while researching some other mineral info I remembered this link I had, which is much more specific than most about the process, particularly with respect to saving detail on pieces

Bill