Glass artists call melting glass in a kiln "slumping." Slumping a wine bottle into a flat surface makes an excellent cheese board. It is a fairly easy process if you have the right equipment. You must understand glassworking terminology, such as annealing, thermal shock and devitrification. Connie Brown of glass-fusing-made-easy.com recommends the steps below to give you a basic understanding of these terms and enable you to slump a wine bottle into a cheese board.
Clean the wine bottle well with soap and hot water and allow to completely dry. Any water, residue from the label, adhesive or soap can cause problems in the kiln later.
Line the kiln shelf with kiln paper to keep the melted glass from adhering to the inside of the kiln. Alternatively, spray it with kiln wash.
Place the bottle inside the kiln and close it.
Warm up the kiln slowly, increasing the temperature around 260 degrees C per hour until it reaches 593 degrees C.
Keep the temperature constant at 593 degrees Cor about 10 minutes. This is known as "soaking" and allows the all the glass in the bottle to reach the same temperature.
Raise the temperature about 250 degrees each hour up to 1,300 degrees. Then turn up the heat and reach 1,425 degrees as fast as possible. If your bottle slumps to the shape you want before 1,425 degrees, stop increasing the temperature.
Cool the kiln as fast as possible to 0-11.667 degrees Celsius; partly opening the lid at this stage will prevent a matt appearance on the bottle called devitrification.
Cool the bottle at about 65.6 degrees C per hour to anneal it. This removes stress from the glass. Turning off the kiln and letting it cool on its own is usually the best way to do this.
Remove the bottle, wash it and serve your cheese on it.
You can use "devit spray" on coloured bottles before putting them into the kiln to stave off devitrification, which is a crystalline layer that can form on the bottle. This dull or foamy finish is not as desirable as a glossy one. Instead of kiln paper, you can use kiln wash, which may also be referred to as separator or shelf primer. You can usually buy this in powder form and mix with water to spray the kiln shelf before firing. To make a hanger for your cheese board, place a looped length of 20-gauge copper wire inside the neck of the wine bottle before it goes into the kiln. The melted glass will secure it in place. These instructions may vary with your kiln, so change them as needed. Each kiln has its own idiosyncrasies, so modify these steps and keep good notes Try other shapes of bottles for different styles of cheese boards. Leave enough room in the kiln for sufficient air circulation around the bottle.
No water should remain in or on the bottle for firing. It could explode. Melting different bottles together is not a good idea. Glass expands at various rates depending on its composition. The rate of expansion is known as COE, or Coefficient of Expansion. Only glasses of the same COE should melt together or cracking will probably occur. According to Brad Walker of Warm Glass Studio in Clemmons, North Carolina, heating up the kiln faster than 500 degrees per hour can cause breakage. Up to about 1,000 degrees, glass is still solid but expanding. If the temperature rises too fast, cracks can occur. This is known as thermal shock.