Brass covers for Keum-Boo on the Ultra-Lite kiln.
This brass set of KeumBoo Covers consists of two pieces: One brass disc has a depression in the middle and is designed for rounded shapes (beads, rings, etc.) The other is flat, so suitable for flat pieces.
Put the disc you want to use on your Ultra-Lite kiln above the element, when cold. Heat it with the brass cover in place. You do not need a temperature controller for this, just fire your kiln "un-controlled".
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 - with fine silver metal clay we have the luxury of it being ready to go as soon as it has been fired! Then you apply 24 carat gold foil using pressure combined with heat, which gives you a permanent diffusion bond.
Our Gold Foil is especially thick compared to most on the market, making it easier to handle, and giving a stunning gold surface.
What is diffusion bonding?
Pure precious metals like gold and fine silver have a similar atomic structure. Heating them to a temperature above 350-500°C increases the movement of the atoms in the metal. Add pressure to that (using a burnisher) and an electron exchange takes place at the surface between the two metals - in very layman terms (as we understand it), this basically means the gold and silver atoms starts swapping places. This creates a permanent diffusion bond.
Learn more in this Keum-Boo on Silver book by Celie Fago.