Today I valeted a Burster that had been parked next to the owners garage, on inspection I noticed a lot of grit like substance down one side of the van. The owner told me this was from the tiles on garage roof "been up there eight years and still the stuff comes off" he said. The point of me posting is to warn anyone who is going to clean their van to be aware that if not washed off with plenty of water or better still snowfoam it could be the same as cleaning your van with Vim