To melt a glass bottle in a kiln, place it on a kiln shelf, gradually raise the kiln temperature to 1425 degrees Fahrenheit and cool the bottle until it is safe to touch. This 18-hour procedure requires a kiln, safety gloves, kiln shelf paper, water, soap, a razor blade and paper towels.
- Prepare the bottle
Wash and dry the bottle. If it has a label, soak the bottle for 30 minutes, and scrape the label off with a razor blade. Dry the bottle with paper towels.
- Insert the bottle into the kiln
Line a kiln shelf with kiln shelf paper. Lay the bottle on its side in the middle of the shelf, and load the shelf into the kiln.
- Heat the kiln
Turn on the kiln. Every hour, raise its temperature by 500 degrees Fahrenheit. When the kiln reaches 1100 degrees Fahrenheit, maintain that temperature for 10 minutes, then resume gradually increasing the heat by 250 degrees per hour. When the kiln reaches 1300 degrees Fahrenheit, increase the temperature to 1425 degrees Fahrenheit as quickly as you desire.
- Inspect the bottle
When you feel satisfied with the bottle's shape, reduce the kiln temperature to 1100 degrees Fahrenheit. Put on heat-safe gloves, and expedite the cooling process by opening the kiln door slightly.
- Cool the kiln
When the temperature drops to 1100 degrees Fahrenheit, close the kiln door, and decrease the temperature by 150 degrees per hour. Leave the bottle inside until the kiln reaches room temperature.