You can see the different layers under the topcoat. Working from the center out, you can see a factory corrosion-protection layer, the lighter gray is original primer, the first blue is the original paint, and finally, a respray build-up primer, the newest old Barbados Blue, and a clearcoat. These layers create quite a ledge between the repair area and the topcoat, requiring the feathering with the 150. A light skim of metal glaze must be applied directly to the dent and carried out beyond the edge of the topcoat. Otherwise, you get a dip between where the paint ends and the glaze begins. The glaze on the original paint will sand off easily.