This is something I have been wanting to try for a couple years. I finally got around to it today. The general technique is well known. See, for example, the following:
My victims experimental subjects were a pair of files:
Here is the setup:
My anode (positive terminal—note the red clip) consisted of two mild steel rods connected by the green wire. This was so the current could connect to the file (the cathode) from both sides. The process depends on the flow of electric current, so to treat both sides of the file both must have a clear line of sight to the anode
The DC power source is an auto battery charger:
8.75 volts (according to my multimeter), and it ran at 5 amps.
I was using ordinary salt rather than washing soda as an electrolyte. Since this gives off a little chlorine gas, I opened a window and started to set up a fan, but then decided to move the whole apparatus outside. Before I started I was worried about whether I could tell it anything was actually happening. Not a problem!
Later:
Each file was in for about 2 hours. After removal from the bath I dried them with a cloth, cleaned the loosened crud off with a wire brush in an electric drill, then sprayed them with WD-40. The results:
The rust is gone. I am pleased.
From Hilbert Space to Dilbert Space, and beyond 