Introduction
If you're just starting out with glass fusing, one of the biggest challenges is understanding how to fire your kiln correctly. Too fast, and your piece may crack. Too slow, and you may waste time and energy. Every successful fused glass project relies on a well-designed firing schedule, especially when working with COE-compatible glass.
This guide breaks down the essential beginner-friendly firing schedules—full fuse, tack fuse, and slump—along with tips that will help you build confidence and consistency.
What Is a Firing Schedule?
A firing schedule is a programmed series of steps your kiln follows to heat, soak, anneal, and cool your glass. Every schedule contains:
- Ramp Rate (°F or °C per hour)
- Target Temperature
- Hold/Soak Time
- Controlled Cooling
Each stage supports a different part of the fusing process, from removing moisture to strengthening the final piece.
Understanding Key Terms
Ramp Rate
How fast the kiln temperature increases or decreases.
Soak/Hold
A pause at a specific temperature to allow temperature equalization.
Annealing
A slow cooling phase that relieves internal stresses in the glass.
Full Fuse vs. Tack Fuse
- Full fuse: Glass melts completely into one smooth layer (1450–1500°F range)
-
Tack fuse: Glass softens and bonds while keeping texture (1325–1375°F range)
Beginner Full Fuse Schedule (COE 90 or 96)
|
Step |
Ramp Rate |
Target Temp |
Hold Time |
Purpose |
|
1 |
300°F/hr |
1100°F |
10 min |
Remove moisture, prevent thermal shock |
|
2 |
600°F/hr |
1475°F |
10 min |
Full fuse melt stage |
|
3 |
Full (as fast as possible) |
900°F |
60 min |
Anneal—relieve internal stress |
|
4 |
100°F/hr |
700°F |
0–10 min |
Controlled cooling |
|
5 |
Kiln off |
Room temp |
— |
Natural cool |
What you get: Smoothly fused layers, rounded edges, and fully integrated glass.
Beginner Tack Fuse Schedule
|
Step |
Ramp Rate |
Target Temp |
Hold Time |
Purpose |
|
1 |
300°F/hr |
1100°F |
10 min |
Pre-process stage |
|
2 |
500°F/hr |
1350°F |
10–15 min |
Tack fuse: texture preserved |
|
3 |
Full |
900°F |
60 min |
Anneal |
|
4 |
100°F/hr |
700°F |
0–10 min |
Controlled cool |
|
5 |
Kiln off |
Room temp |
— |
Complete |
What you get: The glass pieces retain shape (e.g., dots, strips, designs), but fuse firmly to the base.
Beginner Slumping Schedule
Used to shape already fused glass into molds.
|
Step |
Ramp Rate |
Target Temp |
Hold Time |
Purpose |
|
1 |
300°F/hr |
1100°F |
10 min |
Preheat |
|
2 |
300°F/hr |
1250°F |
10–20 min |
Begin slump |
|
3 |
Full |
900°F |
45–60 min |
Anneal |
|
4 |
100°F/hr |
700°F |
0–10 min |
Controlled cooling |
|
5 |
Kiln off |
Room temp |
— |
Finish |
Note: Slumping temps vary based on mold depth and thickness—shallow molds need lower temps.
Tips for Fusing Success
- Use compatible COE glass - Mixing COE 90 with COE 96 will cause stress fractures.
- Keep glass layers clean - Dust, oils, and fingerprints can cause bubbles or devitrification.
- Fire with proper spacing - Allow airflow around pieces to avoid uneven heating.
- Record your results - Every kiln behaves slightly differently—tracking helps you improve.
- Use kiln wash or shelf paper - Prevents glass from sticking to shelves.
Common Beginner Mistakes (and How to Avoid Them)
1. Cracking during cooling
Cooling too fast—ensure proper annealing.
2. Devitrification (cloudy surface)
Avoid over-firing, use clean glass, and consider applying devit spray.
3. Uneven fusing
Place pieces in the center of the kiln and avoid thick variations.
Conclusion
A great fused glass project starts with a well-planned firing schedule. Once you understand ramp rates, hold times, and annealing principles, you’ll have the foundation to create beautiful, consistent work—whether full fusing, tack fusing, or slumping.
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