You may have to clean the windows the traditional way the first time. Then, on a regular basis, use the WFP. I know many WC'ers are doing houses more then once a year now that they have the WFP. As with any WC method, if you clean the windows regularly, the easier they are to clean the next time.

Micah Kommers
We Wash Windows micah@we-wash-windows.com
Greenville, SC www.we-wash-windows.com