We strongly recommend that first-time customers clean both the inside and outside of their windows for two reasons. Often, the inside of the windows are dirtier than the outside, so customers who clean only the outside notice smudges, light film, etc. on the inside more than before the cleaning. Also, over the counter spray-on products do not clean windows as thoroughly as soap and a squeegee and may be harmful to the environment. Once we clean the inside of your windows, further appointments may include only the outside for complete customer satisfaction.