|When glass beads are made using a torch, internal stresses can form, particularly in large beads. These stresses can cause the beads to crack or break – even years later – if they aren’t eliminated. Removing the stress is called “annealing” and is easily accomplished using a kiln, a pyrometer and a little patience.|
- Complete all the steps in “How to Make Glass Beads” (see Related eHows).
- Place your beads on a kiln shelf in a room-temperature kiln, making sure they don’t touch each other.
- Close the kiln, and begin slowly heating it at a rate of about 6 degrees F per minute. Monitor the temperature using a pyrometer (a thermometer that measures high temperatures).
- Wait until the temperature reaches 940 degrees F, then hold this temperature for approximately 30 minutes. This time period is known as the “soaking” time.
- Begin lowering the temperature at a rate of about 5 degrees F per minute until it reaches any temperature below 600 degrees F.
- Turn the kiln off and allow it to return to room temperature before unloading.
Temperatures listed in this eHow are a general guide for Moretti/Effetre-brand glass and for beads up to 2 inches in diameter. Different-size beads will have different soaking requirements, with the largest beads needing the longest time. Always use a soak time to match the largest bead in your batch, as you cannot oversoak a bead.
Different brands of glass have different annealing time and temperature combinations. Get specific information about your particular brand of glass from your supplier.
Different kiln configurations allow for different loading methods. Specialized annealing kilns will allow loading of hot, freshly made beads while still on the mandrel (see step 10 of “How to Make Glass Beads”).
An electronic kiln controller will greatly simplify and standardize the annealing process.
Different brands of glass expand and contract differently when heated and cooled. Avoid mixing different brands of glass rods in the same bead, or stress-related cracks will result regardless of annealing.
Kilns can produce heat of up to 2,000 degrees F, which will burn any organic material.
Quickly applying ice to mildly burned skin will help prevent blistering. For serious burns, get professional medical assistance right away.
Resist the temptation to peek into the kiln before the process is complete. Rapid temperature changes will defeat the annealing process.