When a flat surface is decorated by applying enamel with a brush the result is painted enamel. In this technique, there are no separations on the metal base to contain the enamel. Several layers of enamel are applied using all the colors necessary to achieve the design. Each layer is fused in a kiln and polished. This method was developed in the 15th century but was not used much until the invention of counter enameling (enameling the reverse of the object to maintain the proper tension throughout.) It is also known as Limoges enamel because of its extensive use in Limoges France.