does anyone use soap for there wfp .I can recommend a brand which we have been testing for a couple of weeks , put a little on the really dirty windows A. it cleans your brush out B.. its definitely seems to dry quicker the soap it is an Evans brand of neutral ph called High Class neutral hard surface cleaner costs £4.00 for 5 litre's is mega for cleaning trad windows as well just thought we would pass this on if it helps.we clean about 4 houses without soap then just one window to give the brush a clean gets all the spider crap off,and any window with bird crap on well it works for us happy cleaning Edd