dave
i have lots of windows that bead, just scrub a wee bit more and move the brush from left to right (or vice versa) a bit slower on this kind of glass. also a bit of common sense is needed with the brush on method for example- i keep my brushes as cleen as possible, regularly knocking the leaves/cobwebs etc off them.i'm not trying to say that a brush full of crap will make a good job, but for the people that say the brush is always contaminated and will leave dirty marks,in my experiance thats nonsense.to me there's more chance of contamination brush off.
