I get a little carried away with it. I inspect the pleats, then wash them in a bath of varsol, agitating for several minutes, then I take a neodium magnet from an ID badge on the end of forceps and stir up the varsol, making sure to slide the magnets along all the surfaces, for several minutes. I end up with a light coating of ferrous mud and maybe a few ferrous specks. The dirty Varsol I pour into a black plastic tray, leave it to settle, then drain it carefully and look at what's left in the bottom like panning for gold, which shows up as mostly very fine non-ferrous specks easy to see against the black. Then I breathe another 50 hour sigh of relief.
