The caustic without electrolysis takes care of the paint and goo. The electolysis converts the rust into a stable oxide of iron and is black in colour. In the photo below are 2 outer combat rims pieces. The one at the top of the picture has been stripped of OD by the process and the black on the lower one is the rust converted.They have just been rotated to treat the other half in the liquid. There is no danger of compromising iron/steel but the caustic will destroy zinc, aluminium etc. I lost a data plate on a j**p transfer case - is how I know.
Photo of pickle pot in action although its at a bit of a low tide at the moment.
I use a steel angle iron as the anode and pass the current through it with the circuit being completed with alligator clips on the object being treated. Have to clean spots back to clear metal for the contacts. I power it with a small variable current transformer which was being sold in a hobby shop as a doll's house transformer. In a smaller pot I got away with 6volts but in this larger version increased the voltage to 9v. Make sure the parts and the anode are not touching. Generally cleans the items over 24 hours.
Items require wire brushing after treatment to remove the black film - and need to be primed quickly before the red menace returns. Its our winter and I made the mistake of cleaning some parts and not getting back to prime them for a week and had to do some extra brushing to remove the surface rust formed on the areas where there had been no rust previously.
Cheers
