Some tints are incorporated into the safety glass itself and cannot be removed. These are typical of factory-installed tinted windows. After-market tints are usually applied as a film, which can be removed, albeit with difficulty. These are usually glued onto the window surface and may be difficult to remove. Home-installed, discount tints are often applied without adhesives and can be peeled off fairly easily. The following information was obtained from a local company that installs after-market tinted films (http://www.derand.com/Tints.html): "Is it possible to remove old film in order to reinstall new film? Although the process can be challenging and time consuming, it IS possible. The tinting film has a layer of glue that sticks to the window. Once it dries, it is very difficult to remove this layer of glue. ALL of this glue has to be removed in order to reinstall new film. When peeling off the old film, the glue will certainly stick stubbornly to your window. It is an even more delicate job to remove film on the rear window; not only does the glue remain on the glass but there is also the possibility that the film will rip off your defroster lines."