can i paint flat slate roof tiles with masonry paint as advised by BnQ store wolverhampton. The tiles are on a canopy that covers my front door and stretches along the length of the house. They are not like normal roof tiles but very thin and flat. They look slightly aged and as we just brought the house we wanted to brighten them up. Please advise as I have painted 4 of the tiles today just to see how the paint sticks and looks b4 painting the whole lot. Thanks