I painted a bathroom last week, and I've just noticed that it wasn't just the bathroom that I painted. I've got a patch of painted hair-ends. I've washed my hair several times since I did the painting, so it's not coming off with just washing. It's Farrow and Ball modern emulsion (water-resistant, and for heavier-traffic areas, so it's probably a bit more likely to stick than some paints). Any ideas please?