Glass fusing and slumping are some of the most captivating techniques in kilnforming, but the real magic happens inside the kiln, where temperature, timing, and patience converge. Understanding your kiln firing schedule is critical for achieving strong, beautiful, and structurally sound glasswork.
At Make Santa Fe, we want every member to feel confident working in the glass studio. Based on Bullseye Glass's industry-standard research, this guide breaks down how and why different firing schedules work and how to adjust them for your project.
A kiln firing schedule is a series of temperature changes --- how quickly you heat or cool your glass, how long you hold it at specific points, and when to let it rest. Each step affects the piece's final look, strength, and stability.
Bullseye Glass recommends thinking of your firing schedule as eight stages:
Each stage is carefully designed to avoid cracking, stress, devitrification (crystallization on the surface), or trapped bubbles.
Tack fusing joins pieces of glass just enough to stick them together while retaining their original shape and texture. Edges soften, surfaces may gloss over, but the glass doesn't flatten.
Use it when:
Common signs of a tack fuse:
📌 Example hold: 10--20 min at 1375°F (depending on glass and desired texture)
Full fusing melts multiple layers into a single, flat, unified piece. This is the ideal choice for functional or smooth decorative objects like coasters, jewelry, or blanks for slumping.
What happens:
📌 Typical hold: 10--15 min at ~1490°F; adjust based on glass thickness and kiln behavior
Slumping involves taking a pre-fused piece and reheating it just enough to let gravity gently shape it into a mold.
What to watch for:
📌 Soak temp: usually 1200--1250°F, held for 10--20 minutes or until desired shape is achieved
Bullseye emphasizes that glass behavior is based on heatwork --- a balance between temperature and time. You can get similar results from:
This interplay means no single "magic number" --- every project may need small adjustments.
|
| Step | Rate (°F/hr| Temp | Hold |
| 1. Initial Heat | 400°F/hr | 1250°F | 30 min |
| 2. Rapid Heat | 600°F/hr | 1490°F | 10 min |
| 3. Rapid Cool | AFAP* | 900°F | 30 min |
| 4. Anneal Cool | 150°F/hr | 700°F | 0 min |
| 5. Final Cool | Natural Cool | Room temp | DONE |