Glass and form
Schedule
Presets
Output
Curve colour shifts from molten orange at the top to cold blue as the piece approaches room temperature.
Important
Simulation results are estimates for learning only. Actual glass behaviour depends on your materials, your equipment and your technique. Follow the manufacturer's instructions and take hands-on instruction before working with hot glass.
How it works
Annealing is the least visible and most consequential step in glassblowing. The piece goes into the kiln hot, is held above its annealing point until internal stress relaxes, and is then cooled through the strain point slowly enough that no new stress forms. Get the cooling rate wrong and the piece looks perfect for three days before it splits.
This simulator plots the full schedule as a temperature curve you can drag segment by segment. Press play and a marker walks the curve while a cross-section of the glass changes colour with temperature and shows where stress is concentrating. Push the cooling rate past what the thickness allows and the simulator flags it, because that is exactly the mistake that produces a delayed crack.
Controls
- Glass type
- Soda-lime, borosilicate or lead crystal
- Thickness
- Wall thickness, which sets the allowable cooling rate
- Annealing temperature
- Soak setpoint above the annealing point
- Soak time
- How long the piece is held at temperature
- Ramp rate
- Both heating and cooling rates in degrees per minute
What you get out
- Total schedule time
- Annealing point and strain point
- Segment by segment plan
- Internal stress risk
These simulations are a teaching aid. They do not make anyone competent to operate a furnace, glory hole or kiln. Real work requires eye protection, heat-resistant gloves, working extraction, a carbon monoxide alarm and hands-on instruction.