How to Finish Fireplace Boxes

Put on a pair of work gloves. Scrape the entire fireplace box vigorously with a wire brush. Get into the small cracks in the front to remove all ash buildup, but be careful about chipping or gouging the interior fireplace brick, as long-term exposure to fire can make this brick delicate. Scrape until all pieces of creosote or ash have been removed.

Soak one section of a rag in mineral spirits and rub it vigorously over the fireplace box. Reapply mineral spirits to the rag as needed and work to remove the dark buildup of ash and soot on the fireplace bricks or stones. Continue until the brick is no longer getting cleaner. Allow fifteen minutes for the fireplace box to dry.

Apply high temperature primer using brushes in even, smooth strokes. Fill even the small gaps in between cracks with primer so that the surfaces are completely sealed. Allow primer to dry for six hours.

Apply a coat of high temperature paint to the fireplace box using even, smooth strokes, painting whenever possible in the same directions as the previous coat. Ensure that the paint enters even the smallest cracks, penetrating areas that may not have been coated thoroughly before. Allow paint to dry for six hours and add another coat. Allow second coat to dry 24 hours before having a fire in the fireplace.