After you hit the dent (Dentmaster offers fixing a dent at affordable price) from the out side in, then you should immediately cool off the area with your sponge, and then repeat if you need to, you’ll notice the affected area getting smaller, and smaller.Once you satisfied with the outcome your done with the process, this is a process called heat shrinking, and it does a very good job of removing stubborn dents, and creases in your cars body, it is and advanced technique that I would practice before using on your car.Hopefully this will help you get the stubborn dents out of the body of your car, the ones that just a hammer and dolly can’t do, such as creases, some of these get next to impossible to remove, but if you know how to heat shrink a dent you can remove almost any dent from your car.