You need
- A plastic tank with enough space to hold your part.
- A battery charger capable of at least 2 amps of constant current.
- Sodium carbonate, also known as washing soda.
- Water
- Steel rod to act as an anode.
- Mix the washing soda in the tank at a solution of 1 teaspoon of washing soda for every pint of water.
- Place your part in the solution and hook up the negative lead of the charger to the part itself.
- Hook the positive lead to the steel rod and set that into the solution. Make sure that the steel rod is not touching the part to be de-rusted.
- Set your battery charger to a constant 2 amps, and walk away from your part for a couple of days.
When the process is finished, the part will look black. All of the rust will be gone, and none of the original metal will have been removed.