i've tried alsorts of things over the years. our window cleaner stopped coming about 12 months ago so we've just had a go at cleaning them ourselves, and have to say a bucket of warm water with a little fairy liquid in, and a cloth to wash them first, and then dry with a chamois leather, is the best and easiest method yet. i don't know why it's taken me so long to find out! we've done the inside and outside by the same method. forget any spray on stuff, or even those windscreen-wiper blade things.