Im just about to carry out a complete washdown on a house which has the old roots of ivy all over the frames and sills which are pvc,for that im going to use grade 0000 wire wool which is good for cleaning glass, pvc ect whithout scratching,but for brick this is a hard one ,how about a soft wire brush if that doesnt work then try 1 step up to a harder one ,hope this has been a little help
steve...