Dave, I use old rusted seat frames for my electrode. Due to the large amount of surface area available it derusts your part quite quickly. When its so rusted it slows down a good deal, you just pull it out and drop it on the ground a few times. the bounce of the springs knocks almost all of the rust off and you can use it again. I usually do that several times until the seat frame breaks into pieces. Ive got a pallet of old seat frames lying around just for this.
Bill mentions above that the sediment isnt toxic, but I'd be leery. You'll be dealing with a bit of lead from the old body seams plus the paint residue that flakes off. Best to just wear gloves.
Jeff
