Dontcha hate working with rusty parts? They are hard to clean the rust off of and it never seems to be 100% complete. Now, there's an easy to way to remove rust from parts using electrolysis! Basically, any metal part that can be immersed or is capable of holding water can be done. This includes gas tanks, wheel drums/disks, engine parts, suspension parts, anything!
note: This article was published in the july 2001 edition of The Antique Outboarder. Gary Nyberg of the Puget Sound AOMCI chapter was the author. It is copied below verbatim:
This is a presentation of a simple procedure for removing rust (iron oxide) from steel fuel tanks, steel tools, and steel parts that are not easily accessed or replaceable. Old timers may already use this procedure. If you have ever tried to get the accumulated crud out of a steel rowboat motor or a remote fuel tank and given hours of labor to marginal success, this process may be right for you. I take no responsibility for anything that may happen if users of these suggestions are not careful. In other words, I accept zero liability for damage to either the user or to the materials involved from your application or interpretation of these suggestions. They have been successful for me and for a lots of restoration hobbiests and artifact restorers. Be sure that you read the understand all of these suggestions before starting this process. Then, let the fun begin.
Materials needed:
Rubber gloves
Polyethylene or glass container
Full face shield
12 volt battery charger
Neck and chest protection
Stainless steel electrode
Some insulator to isolate the electrode from the work piece. (plastic lids work well)
Tap water
Vinegar
Washing soda (not baking soda) or lye (Drano or Red Devil)
Procedure:
1. Set out a tablespoon and tap water. You don't need a large quantity of sink drain cleaner or soda base. Wear a good pair of rubber gloves and face, neck and body protection from possible base solution splash. Take this seriously. The same bases quickly dissolve hair in sink traps. We can imagine what they will do to eyes and skin without putting this to a test.
2. Find a sturdy polyethylene or glass container large enough to submerge your rusty work piece. The solution will become pretty nasty looking, so don't use the wife's best pans if you like warm-cooked suppers. With the problem of a rusted interior of a steel fuel tank, I fill the tank with the solution to clean its inner surfaces.
3. Add base crystals at a ratio of one tablespool per gallon of water to your container to make the electrolyte. Add the crystals to the water. Never add water to the crystals. Always follow the instructions on the drain cleaner with regard to what order to add the ingredients.
4. Carefully stir the solution with some disposable: glass, or your stainless steel electrode.
5. You will need a working 12volt battery charger to power this up but DO NOT plug it into the power outlet yet. You will use a piece of stainless steel as an electrode. I use a 1/4 inch diameter stainless steel rod. Never use aluminium because it will dissolve. Stick with stainless steel. It can be used over and over. Even it will be etched by use.
6. Attach the red (+) positive charger lead to the stainless steel electrode and make certain that it is immersed in the solution but never in direct physical contact with the rusty work piece or the fuel tank. A short circuit would then occur and blow the breaker and maybe the charger too. I suspend the electrode from a plastic lid from a cottage cheese container. Any electrical insulator would work if it securely seperates the electrode from the work piece and the negative lead.
7. Attach the black (-) negative lead from the charger to the rusty work piece anywhere but securely so the piece is grounded well. Immerse it into the solution. Your charger is still not powered.
8. Check to make sure that the positive lead is clear of the work piece and not in contact with your rusty fuel tank and that your negative black lead is securely attached to the tank.
9. Power the charger and watch for a steady stream of bubble rising from the positive electrode. Enjoy the labor you are avoiding. The H gas produced by this is harmless and odorless. (I presume H means hydrogen; very explosive when mixed with oxygen. Be careful for no sparks and have good ventilation!) Proximity of the positive electrode to the work piece is important. If using a very small container for the cleaning of a small work piece, use a small electrode. If the container is too small and the + and - are too close, the heat generated can be a problem, so try to keep these leads safely APART. Avoid using a too small vessel to contain the working solution, which will heat up anyway.
10. Rust depth and the size of the object will affect how long it will need to cook. Check after a few minutes by turning off the power, gloving up and looking at the progress in order to estimate how much longer it will take. I have cooked large parts overnight.
11. When the part appears to be black and free of rust remove it from the solution, dry with a cloth, and coat with oil, primer or paint. The black coloration can be removed with a wire brush, a pot scrubber, soap, and tap water. Working with household chemicals can be dangerous but can also be fun and a great labor saver for those of us that restore these iron-laden machines.
Frequently asked questions:
What about galvanized surfaces?
I have cleaned galvanized steel this way and it has been absolutely immaculate when finished and not discolored. I suspect that some zinc was lost in the cooking process. The process will remove only the rust (iron oxide) from steel. No solid steel metal will be lost. I have never tried it on other oxidized metals.
Will the process change the color of the metal?
Steel will appear black when done, but don't despair. Wash it off with a hose or in the sink. It may need some scrubbing with a brush or something mildly abrasive. You will clearly see rusted through holes in a tank bottom if there are any. I just solder them at this point, using a torch to dry it out. Be sure to coat the now freshly clean steel surface immediately so it doesnt begin to oxidize all over again. One can use petroleum based oils, wax, paint or whatever to keep the rust from again attacking your prized work piece.
Are there alternatives to this electrolytic process?
Yes. Once can also choose to not remove any more than loose rust, buy sloshing compound for inside of fuel tanks (KREEM) and seal the interior of outboard tanks. Some sloshing compounds are alcohol (methanol) tolerant. If you decide to go in this direction, you will still need to disassemble the fuel strainer, sight gage, and the other parts from a remote outboard tank before sloshing, so why not just remove all of the rust instead of simply covering it up? We can also wire brush or bead blast and then paint with POR-15 which bonds permanently with rust, sealing it off permanently from further damage. This product is excellent under water, in fenderwells, or anywhere than isn't in direct sunlight. But it isn't as much fun as removing rust electroltically! If you bead or sandblast it is nearly impossible to get every abrasive particle out of the crevices in tank seams.
Can one re-use the base solution?
Yes, many times, if one can stand to do so. It is so cheap and easy to get rid of safely, I just toss it out after one use.
How do I dispose of the solution when I am finished?
Neutralize it by adding common vinegar (mildy acidic) to the base solution. It will probably take more vinegar than lye to safely neutralize its PH. Vinegar won't hurt the yard or mother earth if you hose it off and lessen the acidity of the solution, if you're concerned.
How long do you leave it cooking?
Small, lightly rusted steel pieces will be done in an hour or so. I did a few rusty old wrenches in about that same amount of time the other day. I also cleaned a 5 gallon OMC remote tank in 36 hours with a 6 amp, 12 volt charger, making it clean enough to eat out of after scrubbing it with a rag inside and hosing it out. Just glove up, turn off the charger, and pull out the piece, rinse it off in tap water or wire brush it, and examine things carefully. You'll be able to estimate how much longer it will take to remove all rust.
Will the process damage my part?
The process will not remove any of the solid steel but it will remove absolutely all rust, so be patient. If there is grease, paint or something foreign preventing contact between the solution or negative electrode and the rusted steel, remove this before starting the electrolytic rust removal process.
How do I clean up my messy fuel tank after all rust is cooked off?
Hose it out with water and lightly use a fiber bristled brush to assist in difficult areas. If you arent certain that you have removed all of the particles from a tank or passage, install a filter. When motor designs permit, I often plumb a small, precautionary sediment bowl into the fuel line between an engine-mounted tank and carb in motors that I value, in addition to performing this rust removal process.
That's about all there is to it. Be safe.
So as you can see, doing it this way saves a lot of time and aggravation over conventional methods. Even though the article talks about fuel tanks, anything steel that can be covered in the electrolyte can be derusted.
Additional notes:
Use scrap wire from the battery charger clamps to the stainless steel bolt and to the rusted part. This prevents corrosion of the clamps. The strands in the wire get corroded so be sure to check occasionally. I've found that it's ok if the wire that connects to the rusty part is underwater. The process still works but don't let the wire to the stainless steel bolt get near the water as that connection will corrode quickly.
The best way to make this process go faster is to use the biggest piece of stainless steel you can find. A fourteen inch long SS 4 sided rod was used which MUCH better results. In one instance, the reaction was so furious that the container was full of bubbles and smoke was rising from the water! Eventually, the solution and the part get warm from the reaction. Don't get too close as the solution bubbles like a carbonated drink and the vapors can make one sick. Using stainless steel plate would probably yield even better results due to greater surface area. Note that this process also removes paint which may or may not be desirable.
For cleaning use a Scotchbrite pad, preferably the industrial strength rust coloured ones. The kitchen type fall apart quickly.
Cast iron was tried, but didnt appear to work very good.
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