Clean the copper piece with scouring powder and water. Rinse well and dry. This removes any oil on the surface that remains from the manufacturing process.
Place the copper piece on a flat item such as a coin to raise it slightly from the work surface. This makes it easier to pick it up after you apply the powdered glass.
Hold a small, fine mesh sifter over a catch paper. Pour some colorless powdered glass into it. Colorless powdered glass is known as flux. Do not hold the sifter over the copper piece because some of the glass will fall through when you fill it.
Shake the sifter gently over the copper piece. Cover the copper surface entirely. The layer of powdered glass must be even across the copper. It should be about the same thickness as the copper piece.
Heat your kiln to a good firing temperature. The temperature will be between 1300 and 1500 degrees Fahrenheit, or 750 and 820 degrees Celsius. The proper temperature will depend on the size of the kiln and the piece being fired. It also depends on which layer of glass is being fired. For example, you should fire flux, or the first layer, hotter than other layers. The last layer should be fired hotter and longer than the others as well. A good indicator for firing the flux and the last layer is when the kiln is yellow inside, not dull red.
Place the copper piece on a firing trivet. The piece should contact the trivet in as few places as possible and only on the sides. Place the trivet and copper piece into the kiln using a long-handled fork. Fire it for a minute or less, depending on the size of the kiln and the copper piece, which layer of powdered glass you are firing and the finish you desire. For example, colored layers of the artwork should be fired to an orange peel finish, but the flux and last layer should be fired hotter and longer to produce a smooth surface. You can see the surface finish in the kiln as the piece fires.
Take the fired copper piece out of the kiln with the long-handled fork. Let it cool for about 10 minutes.
Repeat the procedure for all the layers necessary to complete your artwork.
Repeat the procedure to enamel the back of the copper piece. Use odds and ends of powdered glass from previous projects or a layer of flux. The layer of powdered glass should be about 1 ½ times the thickness of the glass on the front. Fire to an orange peel finish.