The slabs of slate are cut to size, shaped, moulded, carved, or incised as may be required, then polished with sand and water to a fine surface. The enamel is then carefully and regularly laid on, or the slab is marbled to a design, then stoved in an oven capable of being heated to 350° F. Some colours require less heat than others. The time necessary for stoviug depends on the colour; experience will teach this. The colouring is then polished with rottenstone and sand and, when a very fine finish is required, completed with the hand.