That potatoe technique is great! The end result looks good. I have used electolysis to remove the rust from my saws. I recently did a workshop in Brasstown, and rehabbed 16 back saws for the class. I made up a rubbermaid container (5 gal type with a wooden bar across the length to hold 8 saws at a time. Around the inside edge I placed rebar hooked in series. The saws were all connected to the negative wire from a battery charger and the rebar to the positive wire. The solution required sodium carbonate (aka washing soda, not to be confused with bakin g soda!). You can make this by heating baking soda in the oven for about an hour at 200 or 300 degrees to drive off a mole of water. The electrolysis took about 2 hours. The rust (ferric oxide) leaps of the saws and migrates to the rebar. I cleaned the sawplates with water and a scrubbie, then oiled them. If you have a brass backed saw, you need to carefully tape the brass part with some tape that will not slide off in water (I used duck tape). Also, no stainless steel parts! The solution can be reused, then just poured out (unless you had some stainless steel in there). Those backsaws were all 12" long, but now I want to do this with my panel saws, so I need to get a longer container (30" or so).