Hi Paul, nylon coating is when you heat the metal, and dip the part into a nylon powder, the nylon sticks to itself, like a sausage skin, if its damaged, water gets in and it swells up, where as powder coating is sprayed on and then heated up in a curing oven, this way the paint sticks to the metal. there is a chap in long eaton, MHP coatings, that do powder coating, and he gets all the parts blasted before coating, very reasonable prices as well, his number is 0115 9464496