Fill a heavy-duty plastic container with water (so that there is no danger of over-spill). The size of the container depends on the size of the part or tool you intend to de-rust. A 5-gallon bucket works for small parts. Larger parts do better in large plastic storage containers.
Add 1 tbsp. of washing soda per gallon of water in the container. Pour the washing soda in slowly and stir gently to mix and dissolve it.
Insert an anode into the container. Use any long, flat piece of steel, stainless steel or iron (nothing galvanized). Stainless steel is ideal because the surface will not deteriorate during the process. The piece must be long enough that one end remains above the surface of the water. The more surface area the piece has, the more effective it will be (especially when removing rust from large items). Clamp it down to the side of the container. The anode and the metal part must never touch.
Hook the black clamp or wire to the piece to be de-rusted. Hook the red clamp or wire to the portion of the anode that sticks above the water. If your battery charger does not have clamps, or the clamps will not stay affixed to the anode or rusted piece, complete the circuit with wires. Attach a 10- to 14-gauge iron, steel or copper wire to the anode and then attach it to the charger's red wire or clamp. Then do the same for the rusted item on the black clamp.
Plug the battery in to an outlet connected to a working circuit breaker. If the circuit is closed and everything is operating properly, you will see bubbles rise from the rusted part and the anode. If the bubbles speed up for any reason, or the charger's meter goes off the scale, the anode and the part are likely touching. Turn the charger off and unplug it. Separate the parts and start again.
Allow the charger to do its work for several hours. There is no such thing as too much here. Once all the rust is gone, the electrolysis won't alter the metal anymore. Do not leave the charger and solution unsupervised for any extended amount of time especially if you have pets or small children. Do not interrupt the power at any time.
Unplug the charger once the rust appears to be removed. Remove the clamps and/or wires from the anode and rusted piece.
Run the part under running water. Scrub away the loose black oxide with a wire brush or a scrubbing sponge (a pressure washer works for larger items). If you encounter rust, place the item back in the bath for another hour or so.
Towel dry the part.
Prime the metal (if you intend to paint it) or rub oil over it immediately. If you wait, the rust will begin to develop again.
Things You Will Need
- Heavy-duty plastic container
- Washing soda (sodium carbonate)
- Squeeze clamp
- 10- to 14-gauge metal wire
- Wire brush
- Do not confuse washing soda (sodium carbonate) with baking soda (sodium bicarbonate). You can easily find washing soda in most grocery stores.
- You can link anodes together with wire connected to the red terminal and rusted parts together with wire connected to the black terminal -- as many as your charger can handle.
- Place very small parts in a wire mesh basket and then connect the basket to the black clamp or terminal. If a piece is too long to fit in the container, you can remove rust on one end and then on another (with some overlap).
- The anode will gradually deteriorate. Don't use anything you intend to use again.
- This method of rust removal will also remove the paint.
- You can pour the used solution out over the grass. It will appreciate the basic solution.