The walls may not look as if they need a bath — after all, dust and soot fall to the floor, right? Most of it does, but just enough clings to vertical surfaces to warrant a seasonal or preholiday bath. Use a sponge and hand dishwashing detergent, washing the surface in sections. A sponge mop makes it easier to reach higher spots. Use two buckets: one for dishwashing detergent solution and another for wringing your sponge. Dry the walls and woodwork with a clean cloth.