hi pip, do as the rest say, then when its all off i get a bucket of not so very hot water, put in a good capful fo dishwasher stuff, like finnish, but it must be the gel type, mix it about in the bucket then get a good cloth wring it out but not too much and rub all over window to wash, then get a squeegee like window cleaners use and take a swipe accross the top l to r after each stroke wipe the sqeegee i.e. after evey stroke, resul sparkling windows with no smears. i do it all the time. good luck and let us know how you get on.