Magnafluxed, now what the F

Ok just got done checking for cracks on a pair of heads and a block with magnaflux. Everything checked out just fine. I started to clean up the block and noticed some of the iron filings were standing up on the corner of the deck. I'm thinking I just turned my block into a magnet, not good.
I read I can wrap the block with the positive lead from an AC arc welder with 5-6 wraps, and then weld on some scrap. The scrap should be clamped on block with ground on opposite side of the scrap. The wraps make a coil and should induce current and a magnetic field. Ground wire should take care of induced current, I think. Anyone ever try this or another method that worked?