Automotive tinting specifics
Heat-Shrinking
Heat-shrinking is the step in window film installation where the installer uses a heat gun to shrink the film over curved glass so it lies flat without folds or fingers.
Modern automotive glass — particularly rear windscreens on coupes and SUVs — is rarely flat. Film delivered as a flat panel will not lie flat on a compound curve without pre-shrinking.
The installer wets the exterior glass, lays the film panel on it, and applies controlled heat to relax the polymer until it conforms to the curve. The film is then transferred to the interior side and bonded.
Heat-shrinking is the highest-skill part of a quality tint job. It is also the step where most amateur installs go wrong — too much heat damages the film, too little leaves wrinkles ("fingers") along the curve.