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  1. #1
    Forum Staff Travis's Avatar
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    How-To: Remove Rust with Electrolysis

    I've posted on other sites about using electrolysis to clean rusty gas tanks, and today I used the same process in a tub to cleaning some steel (and actually remembered to take pics), so I thought I'd share both setups here...

    Here's the setup to clean gas tanks:

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    You need a sacrificial electrode (steel rod), something to hold the electrode in the tank so that is doesn't touch the tank, something to seal the petcock, water, washing soda, and a manual battery charger. The rubber thing in the picture below is a toilet tank flap that I got at the hardware store for $1. The sacrificial electrode (steel rod) needs to be regular mild steel and not stainless steel. Apparently, using stainless will turn the electrolyte (water and washing soda) into a hazardous material because chromium is released into the solution. I've read it will also turn the water yellow and not the normal reddish color.

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    Seal the petcock and fill the tank with water. Add some washing soda and shake the tank a little. You don’t need much. About 1/4 cup in the tank should do. As far as I know washing soda is pure sodium carbonate. Don’t use baking soda. It’s not the same. I went to several stores looking for it but the only place I could find it was at the grocery store. The negative clamp needs a good ground with the tank. You need to make sure the metal rod you stick in the tank doesn't touch the tank. You might want to check with your multimeter to be sure that there is not continuity before you hook up your charger. The electrolysis process is somewhat “line of sight” so you want the rod to bend like I have it. You need a manual battery charger for this because "automatic" chargers won't work without a battery connected in parallel. Attach the positive cable to the sacrificial electrode. Remember the negative lead goes on the part you want to clean, and the positive goes to the scrap steel.

    When you plug in your battery charger, you should see two amps or more. I've read that if you have a 6 amp battery charger, you don't want to see more that than on the meter or you'll burn out your charger. How many amps you see depends on what your battery charger is set to, how much washing soda you have in the water, and how big the electrode and part(s) you're trying to clean are. I've had good results with anything from 2 to 6 amps (my charger is only a 6 amp charger) so I don't worry too much about the amps. Maybe someone else will have more insight on how many amps you want to have.

    Make sure you do this in a ventilated area and check it every few hours. You'll have to clean the electrode every now and then. How long it takes will depend on how bad the tank is. It might take anywhere from a few hours to a few days. Once all the rust is black you're pretty much done. You'll still probably want to do some kind of acid rinse after using this process, but this is a good way to get rid of a lot of rust without harming any good metal.


    Here's one setup you can use to clean parts:

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    If you’re using electrolysis to clean parts in a bucket or tub, you can use sheet metal to surround the inside of the bucket to create a large sacrificial electrode. The setup in the picture above has a piece of round bar welded to the sheet metal electrode, and the positive cable of the battery charger clamps to that. A lot of people use wire to hang parts from a rod set across the top of the tub and hook the negative cable to the rod. These parts were too big to fit into the tub so I'm doing them half at a time and not suspending them with wire into the electrolyte. Again the parts you're trying to clean can't touch the sacrificial electrode. There is a smaller piece of sheet metal in the bottom that only touches the two parts to be cleaned, and those parts are not touching the sheet metal that the positive cable is hooked to.

    The picture below shows one piece of steel after a couple of hours of "cooking". I used a piece of steel wool to lightly clean the center of each side. The left side was in the water and you can see how it turns the rust black.

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    This is after lightly scrubbing the whole piece with steel wool and drying it off (and flipping it around). You can clearly see the side that was in the water. The other part I was trying to de-rust needed a lot more time. I'll post a picture of both parts after they've cooked some more.

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    This process is great because it gets rid of only the rust and not any good metal.

    Again, make sure you do this in a ventilated area and check it every few hours. Also, I can not be held liable if you blow up or burn down your house while trying this out!
    - Travis

  2. #2
    Forum Staff Travis's Avatar
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    Ok so I haven't gotten those other pictures up yet of the other parts, and I probably won't any time soon because I'm heading out of town, but I did cook them some more and process is doing a good job of removing the rust, it just takes a long time when the parts are really rusty.
    - Travis

  3. #3
    I used this process to clean up an old vise several years ago. It took forever but it worked pretty good. I never thought about using it for gas tanks. I'll have to try that out.

  4. #4
    Forum Staff Travis's Avatar
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    Yeah it works well... especially when the tank isn't that rusty. I would still do some kind of acid rinse when you're done though. Doing both will mean the acid rinse won't take as long and eat away too much good metal. The nice part about electrolysis is that it doesn't hurt the good metal at all (from what I've read anyway).

    I've also read that you can use something like electrolysis to coat or plate the inside of the tank. Anyone know anything about that?
    - Travis

  5. #5
    CB750 Member Gunner's Avatar
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    Would you recommend this for a frame? I had planned on just sanding it down and using a wire brust but this seems like it would work better.
    Thanks!
    Last edited by Gunner; 03-27-2014 at 09:18 AM.

  6. #6
    CB750 Member Boulder82's Avatar
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    I've used this process on two really rusty tanks and it worked great. 82 CB750F and 74 MT125. I used a 3/8 rebar in a PVC sleeve with holes drilled in it for the electrode in the tank. It took a few days but removed 95% of the rust. Then I fill the tank with metal rescue or similar liquid rust remover for about 4 hours. Be sure to turn the tank upside down to get the rust in the top of tank. Flush with a little gas and your ready to go. I don't coat tanks anymore, it just doesn't hold up. I ordered Super Washing Soda from Ace Hardware. VJMC magazine had an article on the process a couple years ago.

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