A glass fusing firing schedule looks intimidating the first time you see one, full of segments, ramp rates, and holds. But every schedule is built from the same handful of stages, and once you understand what each one does, you can read, tweak, or build your own with confidence.
| Stage | What it does |
|---|---|
| Initial ramp | Slow climb through the thermal-shock zone |
| Rapid heat | Fast climb through the devit zone to process temp |
| Process soak | Hold at fuse temp — the point of the firing |
| Rapid cool | Drop fast back down toward anneal |
| Anneal soak | Hold to relieve internal stress |
| Final cool | Slow, controlled drop to room temp |
The process soak is your fuse. A tack fuse (pieces stuck but still distinct) needs a lower temperature than a full fuse (everything flowed into one smooth sheet). The anneal is what keeps your piece from cracking days later. Skipping or rushing the anneal is the single most common reason a fused piece breaks after it comes out looking perfect.
Always start from the schedule your glass manufacturer publishes, then keep a firing log. Every kiln behaves a little differently, and your notes become the most valuable reference you own.
When in doubt, anneal longer, especially for thick or large pieces. You cannot over-anneal, but under-annealing will crack your work. And never open the kiln early to peek; a rush of cool air causes thermal shock that splits glass straight across.
A glass kiln with a programmable controller makes multi-segment schedules effortless. I'll help you pick one sized to your work. Spencer — (801) 839-5882.
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