Wrap films (just like paint) are degraded by prolonged exposer to sun and atmospheric pollutants, particularly on horizontal surfaces such as the hood, trunk lid, and roof. Whenever possible, store the vehicle in a garage or at least in a shaded area during the day. At night, protect the wrap film from dew or rain, which may contain acidic pollutants (a common problem in many large metropolitan areas. When a garage is not available, consider using a cloth car cover at night. If your wrap film starts to discolor or turn brown (which is caused by acidic pollution), immediately have a professional remove the wrap film from the vehicle to avoid staining the underlying paint.