Wed Jan 12, 2011 9:58 pm by slindo
I have had mixed results with electrolytic cleaning. It works great at first but seems to do less the longer it runs, so you never really seem to finish. Also, it leaves a pervasive black iron oxide residue, that must be scrubbed off or pressure washed off. Seems I end up beadblasting most of the things I electrolytically strip to get rid of the residue, but if the part is really cruddy the electrolytic stripping first can save a lot of blasting.
Oh, the anode should ideally be as large as the area being stripped/derusted. Not usually possible with a tank, but the more anode you get inside the better. Also it works line of sight, the anode must "see" the area being stripped.
For light rust phophoric acid/surfactant mixes from the hardware store work well. Phosphoric acid, unlike many others, won't attack good steel. Problem with slower acting acids is they end up taking so long you forget about them, and come back and find the part all rusted or eaten to hell.
Sometimes when you got just one part the easiest way is to take it to an automotive machine shop and have them hot tank it.