I sponge painted my red brick gas fireplace with a light cream latex paint that I had used on the paneling in the same room. I painted the black grout between the bricks solid cream. No fillers, no base coats. It has a rustic mottled look since some of the original brick shows through, and you can show more or less brick, depending on taste. This is not for someone who wants a smooth look. No problem with too much heat from fire.