cant answer your question directly but we used to magnetize/ demagnetize screwdrivers with a car battery and a length of wire. get a piece of 12 gauge coated wire and leave a tail as you start wrapping up the barrel like a barber pole. touch the tail end to the positive terminal of the battery and the other end to the negative terminal of the battery for a split second, just enough to make the spark. if it was magnetic it now wont be, if it wasn't it now will be.
