I have several small irregular parts that won't lend themselves to being cleaned with steel wool very well. Electrolysis/molasses method seems messy and id still have to manually remove scale after. I'm thinking a tumbler would work well in my case BUT I have a question about it. The parts in question are wire clips and battery cable hold down clips. Very irregular shapes and small. However being that these clips are essentially spring steel, I'm concerned the tumbler might work harden them. Is this a real concern with this method or should I not be too worried? Is there anything I can do to help prevent work hardening? Also I'm thinking walnut shells for the media. Is there another media I should use. (surface rust removal, NOT concerned with polishing as I will oil stain these parts later). Thanks guys.