Denny the black residue is just magnetite. It can be painted over and doesnt have to be removed. But if your concerned tank the parts again in phosphoric acid and that should get rid of anything left over. Again almost every part so far has been tanked for a few hours, I give it a good scrub and let it sit overnight, softens that old paint right up and it comes right off.
Its also a good idea to either put your parts in the oven on low to make sure all the water evaporates since metal is so porous. A lot of the pieces Ive done are so big I use my large propane torch to warm them slowly, constantly moving and making the part good and hot, but not hot enough to distort anything. I far prefer 30 minutes of scrubbing the hell out out of my parts then with using the darn blaster.
The dangers of inhaling sand and lead dust arent there. I make sure I wear good rubber gloves when scrubbing the parts and I do it out in the driveway far away from our garden so any residual lead sits in the bucket of water or is washed out into the driveway where it shouldnt effect anything.
Another plus is that while sand can remove good metal, the electroysis doesnt. After tanking and scrubbing a 60 year old part you can still read the orignal part numbers off it most of the time.
Joe thanks for the links apparently I lost some of those...
Good luck, Jeff
