As stated above, cover what needs to be and spray ammonia on window. Place a black garbage bag over the sprayed ammonia to keep it from evaporating and place in the sun to help it work quickly ( 30 minutes to an hour depending on outside temps ) WARNING!!! ammonia is very bad to inhale, get in eyes or skin contact. Also, ventilation is your friend, do not do in an enclosed garage and have both doors open. May take more than one application. HTH