Allow the part to cool before topcoating. It is normal for the topcoat to slightly diminish reflectivity. To minimize this loss, only apply enough topcoat to hide the color of the base. To prevent the Gloss Clear from yellowing, prop the oven door open about ¼" while curing to enhance air circulation. If you are having trouble applying the topcoat, make sure that the ground clip is making direct contact with the metal part, that the emitter tip of the gun is clean, and that there is 1 ½ -2" of powder in the cup.