Well, 2 1/2 year old grandson did his usual treatment of the glass patio doors with his sticky fingers. This time I used a spray bottle of 1 part rubbing alcohol and 1 part water to clean the windows. I use this mixture on the athroom mirrors, but never on windows before this. Welllll, the stuff works great and doesn't smear at all. I will be using this 50-50 mixture everywhere from now on. Great on granite too.