Lay down drop cloths. Put on mask. Brush fireplace with wire brush to loosen grit and scuff the surface, to help paint adhere. Vacuum up grit, then wipe down bricks with damp sponge to remove any lingering grease or dust.
Apply primer to grout lines with nylon brush, then to bricks with roller; let dry completely.
Apply two coats of paint; let dry completely after each coat. (Tip: For a frosted effect and covered storage, we painted the backs of these glass doors a pale blush.)