Do this outside, or burn incense to disperse the leftover product. Have the afflicted person lie down, and pass your hands lightly over their head, not touching it but rather attempting to 'rake" the area surrounding the head. Continue to the rest of the body, and finally touch the head lightly with a bit of
iron. As you rake, periodically toss the stuff off to the side (towards the smoke, if indoors) whenever it feels thick.