Specially designed brass covers to be inserted on the Ultra-Lite kiln for firing Keum-Boo.
This brass set of Keum-Boo Covers consists of two pieces: One brass circle has a depression in the middle and is designed for volumetric pieces (beads, rings, etc.) The other is flat, for flat pieces. Heat the Ultra-Lite kiln with the brass cover in place. The cover fits above the element and moderates the heat of the kiln, making it more pleasant to work over.
Keum-Boo is an ancient Korean gilding technique used to apply thin sheets of gold to silver, to make silver-gilt. Traditionally, this technique is accomplished by first depleting the surface of sterling silver to bring up a thin layer of fine silver. Then 24 carat gold foil is applied with heat and pressure - mechanical gilding - to produce a permanent diffusion bond.
Pure precious metals such as gold and silver have a very similar atomic structure and therefore have a good potential for bonding. Heating these metals to a temperature between 500-700°F increases the movement of the atoms. When pressure is added, this causes an electron exchange at the surface between the two metals, creating a permanent diffusion bond. This bond occurs far below the soldering temperature for either metal.
Learn more in this Keum-Boo on Silver book by Celie Fago.