Cooling beads slowly is a must. When purchasing Lampwork beads for your jewerly designs, you should make sure your Lampwork Beads have been correctly annealed. Here is why:
To prevent cracks, beads are cooled in a kiln, where temperatures can be closely regulated. The beadmaker anneals the bead as soon as it comes out of the flame. That means the bead is left to soak up heat in the kiln so that all glass within it is the same temperature.
The soaking temperature is high enough for glass to flow on some molecular level, but not so high that the bead ends up in a puddle on the kiln floor. After annealing, the artist begins to reduce the heat in the kiln, taking several hours to bring the beads to room temperature.
The slow reduction in temperature produces glass beads with fewer stress points, so they're less likely to crack. Very small glass beads are sometimes slowly cooled between layers of insulation. It's not the same as annealing, but the process is usually successful because the small amount of glass in tiny beads cools at a more even rate.