RUST REMOVAL USING ELECTROLYSIS

If you are working on old tractors you will be working with some old parts, the parts may be covered in rust, grease, old paint, and other (unmentionable) material. Search for Rust Removal on the web and you will find a wide assortment of solvents, strippers, oils, and converters. Most of these products range from mildly to highly dangerous. I mostly stopped using them. They never worked as well for me as the label on the containers claimed anyway. Plus, nothing seemed to work much better than plain old scraping, wire brushing, and sanding. Elbow grease is basically free. I'd rather spend a few more minutes with a wire brush than burn my lungs out breathing some nasty solvent.

But then I came across some web sites describing an inexpensive process that was supposed to remove ALL kinds of rust, grime, and paint using nothing more hazardous than washing soda and a low voltage electric current. The process is called electrolysis and it is by far the BEST way I have found to clean all sorts of iron and steel parts. Even some aluminum and brass parts can benefit from a brief dunking.

I started with a 5-gallon bucket. That was large enough to clean small parts that would fit in my powder coating oven and was a good size to see if the process was really as easy to set up as they said and would work for me. The setup is really very, very simple. Fill your container with water (I used water straight from the faucet). Stir in about 1/3 cup of Washing Soda for each 5-gallons of water. Place sacrificial steel electrodes around the edge of the container and tie them together with wire. Hang the parts to be cleaned from a steel or copper wire in the middle of the container. Make sure the part to be cleaned is completly immersed in the water and does not touch the sacrificial metal at any point. IMPORTANT! Connect your positive lead to the sacrificial electrodes and the negative lead to the part you want to clean.

My setup has moved up to a 25-gallon plastic trash can. I'm still using my 2/10-amp battery charger set on the 2 amp setting. It costs very little to operate, it works while I sit and relax or work on other projects, and my elbow is much happier.

Stick "rust removal electrolysis" in any search engine and it should take you to several pages of detailed information. One Problem, like much of the info on the web, apparently most of the people using and writing about the process have no idea what is really happening in their tank. I don't have a degree in advanced physics either, so I don't claim to know exactly what happens to the rust, but based on "expert" studies and my own observations, only the rust that is in immediate contact with good metal is being converted to iron oxide (a black powder). There is also some magnetite but. since that is also a black powder, I really don't care how much of each there may be. None of the rust is being converted to new steel. For really thick rust or painted items, much of the paint and rust is not converted into anything. The gas bubbles forming on the good steel help loosen and push this material off. Some of the rust appears to get "plated" onto the sacrificial metal.

DETAILS

ELECTROLYTE: Electrolyte is the washing soda and water solution in your tank. You only need about 1/3 cup of washing soda for each 5-gallons of water. That is enough to get the current flowing. Adding more washing soda will make the solution more conductive and increase the amount of current flow, but does not appear to speed up the process and may burn out your charger. This is a case where more is not better, it simply wastes energy. You can fine-tune the mixture by watching youe ammeter and stirring in a little more washing soda. If you see bubbles forming on the parts, the process is working.

The electrolyte will last indefinetly, it just gets more and more old rust and paint deposited as sediment at the bottom. If you don't stir it up, it can just lay there. You should have a lid for your tank to keep trash out. A lid also greatly slows evaporation loss. You don't need to add more washing soda when you replace water lost by evaporation. Only the water evaporates, the original washing soda stays in the tank.

The solution strength indicated with just washing soda is a bit caustic. It can be irritating if you have sensitive skin or if you leave it on your skin long enough to get a reaction. Don't splash it in your eyes! I wear safety glasses as a rule in the work shop. It is a good habit to get into. Some people add lye or other ingredients. I don't believe the health risk is worth any benefit these products may have. You might as well just use chemical paint strippers and rust removers.

Washing Soda:

The Arm-N-Hammer product is usually sold as a laundry booster and can be found near the laundry detergents. It's really pure Sodium Carbonate also known as Soda Crystals or Soda Ash. If you can't find the Arm-N-Hammer brand product, look in swimming pool supply stores for a PH booster sich as "ph-UP". Check the ingredients lable. What you want is 100% Sodium Carbonate, NOT sodium BiCarbonate (baking soda), or sodium hydroxide (lye), or any other ingredients.

STRENGTH: If you do find Sodium Carbonate in a swimming pool supply store, it may be PURE Sodium Carbonate. The Arm-N-Hammer Washing Soda may look like a dry powder, but it actually contains about 15% water. Start with much less of the ph-UP product or you may peg your ammeter and burn up your charger.

If you cannot find washing soda and want to try this on a small scale to test it, Arm-N-Hammer Baking Soda will work. It is less effective and there are other disadvantages, but I did it, and was pleased enough with the results to move up to a bigger tank with washing soda.

BATTERY CHARGERS: My power supply is an old Sears Craftsman automatic battery charger. It has a switch to select 2 or 10 amp output and a dial ammeter. I use the 2 amp setting. This is another case where more is not better. Any current flow starts the process. Using the 10-amp setting just wastes energy and makes more heat. Higher current settings may remove paint slightly better. But, once the paint is loose, taking the part out and brushing off the loose stuff works better and saves more time than using higher current settings.

Some automatic battery chargers do not work well for electrolysis. Electrolysis requires CLEAN DC power. Battery chargers convert 120 volts Alternating Current (AC) to about 14 volts Direct Current (DC) for charging. But, some modern automatic chargers do not filter the AC power as well as they should. Any AC power that gets through the charger into your electrolysis tank slows down or can even stop the process. If your system does not seem to work well, try putting a 12 volt car battery in the circuit as shown on the following diagram.

Do not try to use one of the little battery tenders. These small devices cannot keep up with the current draw and you will just be burning it up.

The "fish" swimming in the tank illustrate that the solution is non-toxic, but I doubt real fish would actually be able to survive in it, GRIN.

STAINLESS STEEL: There are some warnings on the web that using STAINLESS STEEL for the sacrificial anode may create hazardous waste. Stainless steel will certainly last much longer than plain steel. The warnings claim that, as the stainless steel breaks down, it releases chromium and other toxic substances into the electrolyte, turning it into toxic waste. I seriously doubt if these warnings are completly true (probably 1% truth, 99% exaggeration). In my ignorance, I am going to stick with plain steel for my sacrificial anode. Mostly because I have an abundant supply of used welded wire fence fabric. You shouldn't use galvanized metal, for the sacrificial steel. but the galvanizing has almost completely weathered away on the old fence material I am using. The fence fabric has a much larger surface area than using a few pieces of rebar. That creates many more "sight" lines to the rusty parts and works great for me.

Other substances like copper, zinc, oil, grease, paint chemicals and alloy metals may eventually contaminate your electrolyte. If you notice strange colors being deposited on your parts, it may be time to drain and clean your tank. I don't bother. The tiny bit of electroplated foreign material seems to have no effect on any of my parts (so far).

MONITORING: Electrolysis with washing soda requires very little monitoring. Iron and steel parts can be left to cook indefinitely with no damage. They may get a little warm, but the process only removes rust and loosens most paint. Once all the rust is removed, the parts just hang in the vat with a little current going through them. I have often left parts cooking overnight. Be very careful with parts made with aluminum, brass, and other metals. Plated finishes could easily be ruined. I have not had any problems using my tank to remove paint from the few non-steel parts I have tried, but you could ruin some non-steel parts if you left them cooking unattended.

LINE-OF-SIGHT: Electrolysis is largely a line-of-sight process. The sacrificial metal needs to be able to SEE the rust. The larger your tank and the more distance you put between the part and your sacrificial metal, the better your tank will be at cleaning odd-shaped parts. Loose paint and dirt can block the process from working on the rust. Most paint is conductive enough to allow the process to work through it and loosten the paint. I have found that it helps to occasionally pull the parts out for a moment and brush most of the loosened stuff off by hand. It can be a bit tricky to get all the rust out of cracks and crevises. I usually still need to do a little wire brushing and scraping before the parts are clean enough to powder-coat them.

It is possible to clean inside something (like a gas tank), you have to set up an inside-out version with the sacrificial metal inside the part you want to clean. I have done this by attaching an insulated wire to a piece of sacrificial metal (big rusty bolt) then wrapping the sacrificial metal with a porous insulating material (PVC pipe drilled full of holes works good). Put the insulated sacrificial metal inside the part you want to clean. Attach the negative lead to the part, and the positive lead to the insulated wire coming from your sacrificial metal, then fill the tank with electrolyte, or sink the whole works into your tank if the part won't actually hold water.

NEGATIVE LEAD: PLEASE make sure your good part that you are cleaning is ALWAYS connected to the NEGATIVE power lead! Hook it up backwards and your vintage part will become sacrificial metal. Remember the RED lead Collects RUST!

FINISHING: The rust attached to good metal is converted to an iron oxide and magnetite. This looks like a black powder on the parts. This residue should wipe off easily as soon as you pull the part out. The clean metal will immetiately start rusting if you don't use something to prevent it. Let it dry on there and it will help keep the parts from rusting if you aren't going to finish them immediatley. You can later put the part back in the tank for a while to loosen the black stuff, or just prime and paint over it. Most of my parts still need some wire brushing and/or light sanding before I feel like they are ready to be finished.

Heavily rusted parts do not come out smooth. The rust is loosened from the good metal, most will fall off. After cleaning, the part will have pits and valleys where the rust was. Electrolysis will not fill those pits and valleys with new steel. For a smooth finish you may need to apply a skim coat of filler.

EXPLOSIVE GAS:

FREEZING

My tank sits outside all winter and usually does not freeze. The washing soda lowers the freezing point slightly below the average low temperature for VA. If the temperature will be significantly below freezing for several days, my tank will start to freeze, unless it is in-use.

This is my tractor grill after an overnight dunking. You can see that it has a dark finish. This is the black iron oxide/magnetite coating that is left as the rust is converted. Layers of paint literally bubbled right off. It finished overnight while I slept! It would have taken many hours for me to strip and clean around all those bars by hand. This is the largest part I have been able to do so far. It obviously has a large surface area, so the current was a bit higher than I liked. I checked on this one a few times to make sure nothing was getting too hot before leaving it to cook overnight. The biggest problem with large pieces is keeping them from making contact with the sacrificial electrodes. Electrical current will always follow the path of least resistance. If the part touches your sacrificial metal it shorts out. This could ruin your charger.

Some people have provided physical protection to prevent the sacrificial metal from touching parts. One of the best ideas I have seen was to cut a piece of 3/4" PVC pipe for each piece of rebar. Drill a series of large holes in the pipe about 1" apart and put the piece of rebar inside. The rebar can still "see" your parts through the holes, but the PVC helps keep them from actually touching.