While the film is best applied with the windows removed, satisfactory results can be achieved with the windows in place. It can be applied over rear window heater elements.
The film can be often cut to size by using the outside of the glass to create a profile of the window: Lay the film onto the outside of the glazing, cut the film to size, then remove the liner and apply to the inside.
When applying to a vehicle window with double curvature, ‘darts’ will appear. Working the film with a squeegee from the centre outward, it is best to ensure that ‘darts’ appearing in the film due to excess material are worked into a horizontal ‘fingers’ at the left and right edges of the material. This enables the darts to be cut, and any cuts can be aligned with heater element lines. Vertical fingers can be removed by using a heat gun to remove excess material, being careful not to blister the film.