Electrolytic Rust Removal

[OlBlueCJ7]

Is stupid simple, and it works.

Safety notes:

#1 This process produces hydrogen gas. Hydrogren gas ignites easily, and burns quickly. Remember the Hindenburg? Yeah - bad juju. Do this stuff outside, and away from any sources of ignition.

#2 This process involves mixing electricity & water, which is an inherently stupid thing to do. Use some common sense here people. If nothing else. plug the battery charger into a GFCI outlet.


Anyways, on with the story:

So I've got these bump stop brackets that have been on my Jeep, unpainted & untreated in any way, for the past three months. They're starting to rust pretty good, so I need to take them off & paint them.
http://www.gallery.markspeterson.com/d/7321-2/P2170005.JPG

Problem is, getting a brush inside that bracket part is going to be difficult, if not impossible. I'd heard about electrolytic rust removal before, so I figured I'd do some hunting around & see what info I could come up with.

After doing about 30 seconds of research on Google, I found out all you need is:
A bucket of water
An automotive battery charger
Some sodium carbonate.
A rusty piece of metal
A kinda clean piece of metal

For the uneducated like me, this is what sodium carbonate looks like:

http://www.gallery.markspeterson.com/d/7327-1/P2170008.JPG

Note that this is sodium carbonate, not sodium bicarbonate. Sodium bicarbonate is baking soda. Rumor has it baking soda will work, just not as effectively. On the other hand, what either of these things have to do with electrolysis, I have no idea.

Step 1
Put a bunch of the washing soda in the water. I think a tablespoon per gallon is what is recommended. I used about half a handful for the bucket I was using. No science whatsoever. Mix it up, and make sure it all dissolves.

Step 2
With your battery charger UNplugged, connect the leads to the two metal pieces. The positive lead goes to your clean piece of metal (aka sacrificial anode), and the negative lead goes to your rusty piece of metal.

Step 3
Place the two pieces of metal in your bucket of soda water, on opposite sides of the bucket. The parts do not have to be completely submerged - they can be rotated & repositioned later on, if need be. Make sure the two pieces of metal are not touching each other.

Step 4
Set your charger to 12v, 2 amp charge, and plug it in. Hopefully no sparks. If you see sparks, it's probably best to unplug & disconnect everything, and take your piece to the local sandblaster.

Here's what my setup looked like:
http://www.gallery.markspeterson.com/d/7355-1/P2170009_001.JPG

If all goes well, within a few minutes, you should see fizzing off the the rusty part, and bubbles on the surface of your 'clean' metal. Depending on the size & rustiness of your part, let it sit for a while. I let my piece sit for about two hours.

After the two hours, I pulled it out, and with a soft bristled toothbrush, was able to essentially 'wipe' away any rust that had previously been on the piece.

Some before & after shots:
http://www.gallery.markspeterson.com/d/7359-2/P2170015.JPG

http://www.gallery.markspeterson.com/d/7344-1/P2170014.JPG

The dark/rusty spots you see on the cleaned piece is where the part wasn't submerged for the cleaning process.

As for the science behind how any of this works, I have no idea. I just plugged a car charger into a bucket of water, & lived to tell about it. I figure it's worth telling someone about. :D

[jmhinescj]

Iv'e used it before on knuckles and other stuff that has hard to wire brush crevises...it works good but it's pretty time intensive

[Aces'n'8s]

Yeah...I tried that once with at tray full of bolts. It worked well, but I could tell some of the bolts didn't have good continuity so their rust didn't shed too easily. Another go around, and they all came out much cleaner than I anticipated.

Thanks for the recap.

[OlBlueCJ7]

Yeah...I tried that once with at tray full of bolts. It worked well, but I could tell some of the bolts didn't have good continuity so their rust didn't shed too easily. Another go around, and they all came out much cleaner than I anticipated.

Thanks for the recap.

If parts are oily, it won't work as well. The oil stops the soda water mixture from getting to the metal. I bet if you sprayed the parts off with brake cleaner first it would help.

[socalchef]

im totally gonna try it with some ubolts i ordered in the wrong size that are way fawkin' rusty now...totally forgot about this process

[Bub]

They just covered that on a Trucks recently, cool to see it really works.

Bub

[PTSchram]

The same process can be used to remove plating.

[Wicked_S10]

can it be done on aluminum (like an intake manifold) to remove baked in grit and shit, or is it a rust removal deal only?

[thelbz]

Forget the lame battery charger, if you have one use a 100% duty arc welder turned all the way down works way better than the battery charger.
Just my .02

[PTSchram]

can it be done on aluminum (like an intake manifold) to remove baked in grit and shit, or is it a rust removal deal only?

It will only remove corrosion, not the grit and shit. You're better off with a big pot of boiling dishwasher soap.

[beater82]

Well, I've got my old century 295 ac. Now all I need is a doughboy pool and my frame and cab are restored.:eek:
As long as I don't fall into the damn thing.

[jasonmt]

Well, I've got my old century 295 ac. Now all I need is a doughboy pool and my frame and cab are restored.:eek:
As long as I don't fall into the damn thing.

The power source needs to be DC and if you do use a DC CC welder as a power supply the off gassing can be pretty high, ask me how I know...

[NICKC]

ok howd you know? :confused: :flipoff2:

[jmhinescj]

here's a pretty good link on it...alot more info and some safety stuff you should know about before trying it

http://www.shopfloortalk.com/forums/showthread.php?t=1695

[budget76]

Nice write-up:smokin: Might have to play with this tonight

[1TON73K5]

here's a pretty good link on it...alot more info and some safety stuff you should know about before trying it

http://www.shopfloortalk.com/forums/showthread.php?t=1695



Thanks for the link, bookmarked.

[sn0border88]

I went a little overbored and took a plastic 55 gallon drum and turned it into a tank. Stainless steel anodes wont get eaten away like steel ones will, but supposedly they give off all kinds of bad nasty stuff.

Also, I used lye instead of washing soda. :evil: It helps cut oil and grease and works better imo. I take axles and do them half at a time, only takes about 3 hours per side depending on how bad they are. Take them out, wirebrush the lose scale off and wash clean.

Important thing to remember is that it works "line of sight" so if your anode(s) cant "see" part of the material, it wont get cleaned. I took a dozen strips 1" wide and hung them around the perimeter of the tank and wired them together.

[budget76]

I went a little overbored and took a plastic 55 gallon drum and turned it into a tank. Stainless steel anodes wont get eaten away like steel ones will, but supposedly they give off all kinds of bad nasty stuff.

Also, I used lye instead of washing soda. :evil: It helps cut oil and grease and works better imo. I take axles and do them half at a time, only takes about 3 hours per side depending on how bad they are. Take them out, wirebrush the lose scale off and wash clean.

Important thing to remember is that it works "line of sight" so if your anode(s) cant "see" part of the material, it wont get cleaned. I took a dozen strips 1" wide and hung them around the perimeter of the tank and wired them together.

Nice:smokin: If I had the room I'd do the same.

I like the line of sight idea, I'm going to have to set mine up better now

[Albin]

This also works great on cleaning up old cast iron cookware. I've done it a couple times, works well. Good reminder that the sacrificial steel needs to be clean, so take or wire brush off all the old paint and grease etc.

The SFT link is a good writeup, it's what I used.

Al

[Joe_88k5]

I'm going try doing an entire K5 frame next month. I'll post up some pics when I get to working on it.

[Mechanos]

I'm going try doing an entire K5 frame next month. I'll post up some pics when I get to working on it.

It's been my experience that the larger the piece you're working on, the more current you have to give it. On something the size of a full frame, you'll need multiple anodes all around the frame.

Are you going to dig a pit and line it with plastic? Or are you goind to build a plywood box and line plastic? Or what? I've never tried anything on that scale, but I've done a bunch of t-case, adapters, etc.

[GMGuy]

Somebody who did a trailer frame;
http://antique-engines.com/trailer-electrolysis.htm

Alex.

[RockHammered]

Just for clarifications sake, your positively charged, clean metal, sacrificial parts are cathodes, and the rusty part you are cleaning is the anode.

[Mechanos]

Just for clarifications sake, your positively charged, clean metal, sacrificial parts are cathodes, and the rusty part you are cleaning is the anode.

And you'd be right.... if this setup were a battery...
anode: the negative terminal of a voltaic cell or battery.

But since this is an electrolysis tank...
anode: the positive terminal, electrode, or element of an electron tube or electrolytic cell.

So, in that case.... you're mistaken and in need of a little clarification yourself. :flipoff2:

[PTSchram]

Important thing to remember is that it works "line of sight" so if your anode(s) cant "see" part of the material, it wont get cleaned. I took a dozen strips 1" wide and hung them around the perimeter of the tank and wired them together.

This is not at all the case. What you have happening is that the material that is nearer to the electrode has a higher current density and therefor, it will be stripped first. If what you said were true, the insides of the parts wouldn't get stripped. Poor control of current density can result in the destruction of portions of what you're trying to strip while other parts are untouched.

The reason that platers use either multiple electrodes, or conductive tanks is to try to equalize the current density on the parts to get a smooth consistent plating thickness.

Electrons are lazy, they will ALWAYS take the path of least resistance-well, if you believe in the existence of electrons!

To add to the safety comments, Hydrogen gas has the widest flammability concentrations, ie, it will combust at very low concentrations and also at VERY high concentrations. Secondly, the alkaline/basic/caustic stripping solutions WILL cause immediate and irreversible damage to your eyes, wear your fawking safety glasses. It takes very little lye to blind a person! The oter materials are less drastic, but will do serious damage to your eyes.

[gte719p]

Electrons are lazy, they will ALWAYS take the path of least resistance-well, if you believe in the existence of electrons!



Dare I ask Who doesn't believe in electrons?

[PTSchram]

Dare I ask Who doesn't believe in electrons?

DOOOD! It's a quantum physics joke!

(FWIW, I'm not always sure that I believe in sub-atomic particles, in spite of my having worked in elemental spectroscopy for many years.)

[sn0border88]

Ok let me restate. It works 99.9% better and faster if you have the piece surrounded by cathode/sacrificial anode/whatever

[Joe_88k5]

It's been my experience that the larger the piece you're working on, the more current you have to give it. On something the size of a full frame, you'll need multiple anodes all around the frame.

Are you going to dig a pit and line it with plastic? Or are you goind to build a plywood box and line plastic? Or what? I've never tried anything on that scale, but I've done a bunch of t-case, adapters, etc.



I was originally planning on doing the entire frame in a large box, but I'm really just going to do the frame rails now (scrapping most of the factory cross members). I'm going to build a plywood box big enough to fit a frame rail and a bunch of scrap metal anodes, and line it with rubber roofing material. I'm going to try to get more anode surface area than frame surface area to make the process as fast as possible. We'll see how it goes. The only thing I'm worried about is having to take all the black oxide off the frame afterwards, that will be a pita.

Has anyone left the black oxide on a part before? Will it just convert back to rust, even under paint?

[budget76]

Joe, I've found that that black gunk comes off VERY easy with a wirebrush. Not sure what happens with it if you just leave it.

[PTSchram]

Has anyone left the black oxide on a part before? Will it just convert back to rust, even under paint?

The black oxide process is pretty similar to what we're doing here, however, it is done with a much more concentrated solution of sodium hydroxide and sodium nitrate (it's a super-saturated solution that does not become liquid until heated to about 300' F). Black oxide is what most folks are referring to as bluing on firearms. If not oiled, or otherwise protected, it will eventually rust.

[Joe_88k5]

I prolly shouldn't have called it black oxide, I just meant the black crap left over from the electrolysis process. I read somewhere that it was some form of oxide. Is it going to cause problems if I leave it on the frame? If it comes off easily with a wire brush like budget76 says then it's no big deal I guess.

[budget76]

Joe, I don't know what you'd do about the inside of the rails, but the outside will be ridiculously easy to wirebrush off. Picture wirebrushing off yogurt, I feel like that's an accurate description of how easy it is:)

[sn0border88]

Yup, wirebrush and wash it off. I would wear gloves because that stuff is a pain to get off and makes a real mess. It will rust if you leave it on or take it off.

[Joe_88k5]

Ok cool, sounds like a combination of wire brushing and the pressure washer should have it cleaned up in no time.

[RockHammered]

So, in that case.... you're mistaken and in need of a little clarification yourself. :flipoff2:

I stand corrected. :)

[flip2spin]

Maby i missed it but how many amps do i put the charger on ?:confused:

[sn0border88]

Any of them will work, I leave mine on the charge/start setting overnight all the time with no problems. I think its 50 amps for that?

[PTSchram]

Maby i missed it but how many amps do i put the charger on ?:confused:

Current really won't be all that critical as reduction and oxidation potentials are expressed in volts-it's the amount of voltage necessary to make the electrons (for those of you who believe in them) do their stuff.

That said, if you crank the current up too high, you WILL have problems with dissolution of the parts you're working with. I did this once stripping gold plating from a pair of microphone windscreens! Oops, I ended up having to buy another set for my client and then repeating the experiment, but at less contact time.

[PTSchram]

For those of you who are real nerds and want to learn how this is done in the real world...

http://www.pfonline.com/articles/pfdenthone01.html