A small amount of copper wire, screen, sheet or foil can be added to fused-glass creations. For best results, the copper should be limited to no more than 20 percent of the total size of the piece and the copper should be laminated between the glass.
Clean the copper with acetone to remove any dirt or residue that could contaminate and react with the glass. Rinse with water.
Use scissors, a knife or a craft punch to cut out your designs from copper foil, screen or sheet.
Use a wire cutter or jewelry saw to cut copper wire can be cut with a wire cutter or jewelry saw. Form the wire into the desired shape. Depending on how you shape wire, air may be trapped when the piece is fired and bubbles may form. If you do not want bubbles surrounding your inclusions, consider how the shape will allow air to be released from your piece as it fuses. For example, complete circles are likely to trap air. Open arcs are more likely to release air. Of course, sometimes the bubbles are part of the attraction and can add to the design.
Place the copper inclusion on the bottom piece of glass. Take care when placing the copper to not leave fingerprints. When you are done arranging your design, cover it with a clean, clear piece of glass. Do not place the copper near the edge of your piece. Copper inclusions that are close to the edge may interfere with the fusing of the glass.
You can use a touch of glue to hold the copper in place. If you choose to do so, it is important to wait until the glue is completely dry before putting the laminating piece of glass over the design and putting the project into the kiln.
Fire the piece in the kiln. Copper inclusions in glass must be fired very slowly in the first ramp. Heat the glass 150 degrees Fahrenheit per hour until the glass reaches 350 degrees Fahrenheit. Hold the glass at 350 degrees Fahrenheit for 30 minutes before proceeding in your fusing cycle.
Although it is best to wait until the piece is room temperature, you can remove it from the kiln once it reaches 300 degrees Fahrenheit. The best practice is to allow your fused piece to remain at room temperature for 18 to 24 hours before placing it in water and washing it.
Copper will oxidize and turn a reddish-brown during the fusing process. This is normal. Remember, the cleaner and less oxidized the copper inclusion is before it goes into the kiln, the brighter the color is likely to be after fusing. Copper can be embossed to add texture and depth to your piece. Place the copper sheet on a soft surface — a computer mouse pad or a magazine, for example — and trace the pattern you desire with a pen.
Always wear eye protection when cutting glass. Always wear a dust mask when working with glass particles. Glass, particularly vintage glass, may contain lead. Copper may also contain very small amounts of lead. To avoid thermal shock, do not open the kiln when its temperature is between 500 degrees Fahrenheit and 1000 degrees Fahrenheit in either the heating up or cooling down phases of fusing.