Electroylsis Rust Removal

[Luv2Wrench]

I've run across several websites describing a method of rust removal using electrolysis. Since I had everything I needed to give it a try, I decided to give it a go and take some pics as I went.

Briefly, the electrolysis setup has the rusted part connected to the negative lead of a DC power supply (12V typical) and suspended in a water/sodium carbonate solution. Surrounding (and not touching) the rusted part should be multiple electrodes connected to the positive lead from the power supply. The specifics on how electrolysis works can be found here: The science behind electrolysis

For my setup, I took a 50gal drum and cut the top off. Added a drain at the bottom, fitted a piece of plywood around the top to hold the electrodes (concrete rebar) in place. Four seemed to work well for the 50 gal drum, but if I were doing it again I might try 6 or even 8. I added Sodium Carbonate (pH Up Pooltime 6 lb. pH Up - 23356PTM at The Home Depot ) and filled with water. I wired up my first part, connected the power supply and turned it on. Almost immediately streams of tiny bubbles started all around the suspended part. Since this is the negative side (Cathode), this is hydrogen. Flakes of rust will start falling off as well and migrating towards the anodes.

A few safety notes:

1) Sodium Carbonate is a big time base. The solution will irritate your skin. Wear chemical gloves. I added a drain on the bottom of the barrel so I could easily empty it after use. In hindsight I am really glad I did that. It makes it very easy to drain and thus not leave a 50gal vat of a natsy solution around for the neighbor's cat to drown in.

2) Those cool bubbles coming up are hydrogen. Hydrogen can explode. Easily. All you need is an ignition source which you have in the form of a spark from the positive and negative leads. First, you must have very good ventilation so you don't collect hydrogen gas. Second, keep the leads from touching. Turn the power supply off before adjusting/removing the parts.

3) 12V DC isn't that big a deal, but it can hurt. Don't grab the leads!!

Other notes:

Polarity makes a BIG difference. Negative on the rusted part, positive to the electrodes. If you reverse this... you will destroy your part as it will be removing rust from the electrodes rather than the other way around.

The typical power supply mentioned on the web is a battery charger. I don't have one that isn't 'smart'. The smart chargers quickly figures out there isn't a battery attached and shuts down. Fortunately I had some 12VDC 20amp power supplies PR20 - 20-Amp DC Power Supply - Precision Regulated AC-to-DC Conversion laying around the shop. These worked really well as they could drive a lot of current and have huge heat sinks to deal with it. I did put a fan next to the supply as the heat sinks were very hot.

Since this whole process works based on the flow of electricity, the part (and all sub-parts) in question must conduct electricity. That usually means using a wire wheel to clean off several areas on the part and connecting all of those areas with a wire. Measure this with an OHM meter to be sure. The better the connection, the better the current flow and the better the rust will be converted.

Note the bearing on the gear shaft in the third picture. I didn't connect that with a separate wire and it is still 100% rusted.

The process is also 'line of site'. If the rusty area of the part can't 'see' one of the electrodes, there will not be much if any improvement.

Parts don't come out magically clean. The process breaks the rust (Fe2O3) down by removing oxygen. While a lot of rust does float away, some is still on the part but only like a film. A little work with a hose and wire brush and then your part is clean. Also note that it is a little 'black' and needs to be finished and protected quickly or it will rust back over.

In some cases I got great results in a few hours. In other cases it needed to be more like overnight. At first this seemed like and issue but later I learned to just set a part in before quitting for the night. Just a little work with a wire brush the next day is all that is required. The beauty here is that it is working while I am sleeping.

When dumping the water out, note that grasses and bushes will love the iron rich and high pH water. Flowers, not so much.

Pros:

For me, the biggest benefit of this process was its ability to get parts/bolts/nuts that were rusted together apart. Bolts and screws came out much easier after this process than if I had just blasted/scraped away the rust.

It breaks down rust and rust only. No metal is lost. This is great for delicate parts. Works great on brass, copper and other metals. My C-clamps came out stupid clean.

It works alone. Turn it on and leave it.

Cons:

It is a fair amount of trouble to wire up the part, wait for the process to complete, remove part and clean up. Blasting away with a media blaster is just quicker and easier.

If your part doesn't fit neatly in a 50gal barrel then you've got to find a kiddie pool or build something. This could be much more trouble than it is worth. However, if you are working the one and only, super delicate, can never be replaced part... then a special tank is no big deal.

Edited July 24, 2011 by Luv2Wrench
Polarity note (see edit history)

[michaelod]

I have done electrolysis rust removal as well. Your setup is very nice but an alternative and simpler solution can be setup in less than 5 minutes. All you need is a non-smart battery charger, plastic tub filled with water in which to place your part, a couple of pieces of rebar from home depot, some Arm & Hammer washing soda (baking soda will work just as well) and you are in business. I have done this many, many times, always with success. The rest of your observations are correct.

Thanks,

[Guest danceswithpumps]

Great topic and pics! I restore old gas pumps and have found electrolysis works great in removing not only the rust but the many layers of paint many old pumps have. I've used acid dip, paint remover chemicals, sand blasters and I have been real pleased as it is much cheaper and I can be doing other things while the battery charger and Arm and Hammer are doing their thing.

This is one of the best thing I've learned about on the web. The pros really outweigh the cons in my opinion.

I might add that the process works best with 70ish degree or warmer is used.

Rod

[Rusty_OToole]

Dont know if this is significant or not but the electrolysis also seems to keep off rust. As an experiment I cleaned an old wheel this way about 5 years ago. Then painted it and hung it up outside for a garden hose reel. It never rusted and the paint never peeled or cracked.

[Guest rsd9699]

Nice setup - I use baking soda and dumb charger and a little soap - love to sleep while it is working away. It will pull paint if there is poor adhesion - love that part too. Water gets dirty but when not in use it settles to the bottom so your plug is handy. Flash rust is a problem for me - does that before my very eyes - so you got to be quick.

Ron

[JV Puleo]

I've been doing this now for three or four years. I'm up to my "MK V" model tank, a long plastic bin from Lowes and an equally long clamp that holds 6 pieces of rebar. I have a 2nd tank made from a fiberglass sink. I especially like rebar because the process rots the anode away... rebar is cheap and easy to replace. I find I get the best results if I pull the anodes out every day and clean them off. I've never had the fast results people report though most of what I work on are excavated medieval and earlier arms. I usually scrape a very small clear spot in some inconspicuous place and wrap copper wire around it. The wire is then used to suspend the piece or pieces from a copper tube with the battery charger connected to it.

This is the preferred system in the museum world, often done for very long periods of time and under very controlled conditions. For instance, distilled water is recommended (I use the runoff from a bid dehumidifier).

Right now I have a jug from a 1908/09 Mitchell in the tank hoping to get the valve cage out and I expect the piece to be in there for weeks, if not months.

Edited August 7, 2011 by JV Puleo (see edit history)

[Luv2Wrench]

Great info from others, thanks for posting.

I've decided to do the body parts with this technique as well so I will be building one or two large tanks. I've got 6 of these 12VDC power supplies so that will not be a problem. The wife isn't thrilled with the idea but a couple nice dinners out should help with that.

For flash rusting after removal I found something that works well for me. I spray the part with Phosphoric Prep and Etch and give that a gentle wash/brush. It will protect against rust for days/weeks and gives me plenty of time to get primer on. Wear goggles and gloves. I like to do this outdoors and have the hose running. Any splashes can be washed off real quick and I haven't had any skin issues.

Edited August 8, 2011 by Luv2Wrench (see edit history)

[Guest rsd9699]

Even if off topic - I would like to see some of JV Puleo results. I would guess that the rust of a couple of hundred years might take a little time to dislodge.

You are correct about needing to clean the rebar as they get covered with less conductive trash that slows the process down big time.

Ron

[JV Puleo]

I'll snap a picture of the 16th century spur I just finished. I have a whole collection of much older excavated bits I'm about to start so I'll take you a before and after.

The nature of rust has much more to do with the material than it does the time its exposed. Cast iron, for instance, is almost rust proof. I rebuilt a big lathe that stood out in the weather for 15 years. Some of the steel parts... nuts, bolts and 2 gears were so eaten away they had to be replaced. The iron itself, even the ways, was hardly effected. The same is true for wrought iron... the less it is alloyed with other materials, the more resistant to oxidation it is, which is why things like 10th century spear heads survive. Cast Iron made in the last 50 years from scrap having steel inclusions is much more likely to pit than cast iron made 80 years ago from ore. Hardening also provides some rust protection. A hardened gear will hold up much better than an unhardened one

Its all very interesting stuff and worth knowing about if you're interested in really old cars. I wouldn't hesitate to buy a rusted solid engine that had been sitting out in a field for 60 years if all the main castings seemed intact... you can almost guarantee it would be restorable although lots of work to get it apart.

[Rusty_OToole]

When not in use cover the container. I didnt and kept finding drowned rodents.

[Willys77]

..........but, "Rusty" ~ I just have to ask, ........"were the RODENTS rusty or not?" Awaiting your reply! Thanks for letting us know!

[KenHupp20]

cheaper than D-Con !