It is absolutely imperative that a hairdryer or heat gun is used in this area to seal the edges. The heat serves two purposes. First, it helps evaporate the remaining alcohol/water solution from under the edges, and second it makes the plastic more pliable so that it can contour to the shape of the light. Be careful if you are using a heat gun to warm the plastic. It takes only a small amount of heat to apply the material. If you apply too much heat you can damage the surface of the plastic.