You can create intriguing art by melting bottles flat. You can use these flattened vessels as cheese platters or paint or hang them to create original art projects. Using a kiln, you heat the bottle to extremely high temperatures and melt (slump) the glass to get the shape that you want. This process may take some practice, as not all kilns perform the same, so it is best to take your time and have several bottles on hand to practice with.
Use a hair dryer to heat and peel the bottle's label off. Alternatively, place the bottle in a container of warm water, so that it can soak for a few minutes, and then scrape it off.
Clean the remainder of the bottle with soap and water and allow it to dry.
Spray the bottle with a devitrification spray, such as Fusemaster Superspray, to keep the glass from getting a cloudy or bubbly appearance.
Place fibre paper or kiln wash, available at ceramic and glass art suppliers, on your kiln shelf. This will keep the glass from sticking to the kiln when it melts.
Slumping the bottle
Place the bottle on its side and, if desired, stick a piece of 20 gauge twisted copper wire inside the neck. This wire becomes attached to the bottle and allows you to form it into a loop to hang the flattened bottle as a glass art piece.
Set the kiln temperature to 593 degrees Celsius (1100 degrees Fahrenheit) and hold this setting for 10 minutes. This holding time allows the complete bottle area to absorb the heat.
Raise the kiln temperature 121 degrees C (250 degrees F) per hour until it reaches 704 C (1300 F). Once reached, increase the temperature to 801 C (1475 F), as fast as the kiln can attain this point.
Keep the setting at 801 C (1475 F) until the bottle has melted (slumped) as much as you want it to. Use your kiln's viewing window to check the bottle or else quickly open the door to see the level of flatness. It typically takes 10 minutes at 801 C (1475 F) for the bottle to go completely flat.
Quickly lower the temperature to 593C (1100 F). The fastest way is to open the door (flash vent), so that the internal kiln temperature drops rapidly.
Cool the kiln back down to room temperature, at a rate of 65.6 degrees C (150 degrees F) per hour or slower, to anneal the glass. If there is a digital controller on your kiln, you can set an anneal program to meet this requirement. Otherwise, closely watch the progress to manually adjust the temperature, as necessary.
Remove your flattened bottle and make sure there is no kiln wash sticking to the body. If there is, simply remove it with soapy water. The bottle is now ready to use for your art project.
Vessels that are larger and thicker than typical wine bottles may need to have the kiln temperature raised at slower rates and will require longer annealing times. Experimentation is needed to determine what works best for your bottle and kiln. If your bottle cracks in the kiln, slow down the heating or cooling rate. Anneal the bottle longer if it cracks shortly after coming out of the kiln.