Thinner films tend to crack or even melt when too much heat is applied. It is very difficult to achieve a consistent, uniform temperature using a propane torch or a heat gun, but the steamer makes this task easy. When the steam is applied, the vinyl is rejuvenated and more pliable, and thus easier to remove. First, test the steamer on a non-visible surface, such as the wheel well, to make sure you won't damage the vehicle's paint. If there are no problems, you're ready to start the removal.
Good technique is essential.
It's best to begin on one corner of a given graphic. Hold the end of the nozzle, with the proper attachments, to the corner for about five seconds. Use your finger, a pin or a plastic putty knife to lift the corner of the film and adhesive away from the surface. In doing so, you will prevent adhesive from remaining on the surface. During removal, you will see that the adhesive usually becomes stringy.