Fused glass is such a fun and rewarding medium to work with—but when you’re just starting out, it can definitely feel a little intimidating.
I still remember my first few projects: I had no idea which glass types worked together, I didn’t fully understand kiln schedules, and I definitely didn’t know how much glass would spread during a full fuse. (Let’s just say… some of my early pieces had a mind of their own.)
The good news? A lot of those beginner struggles are totally avoidable once you know what to look out for. So if you're just getting started, here are 10 of the most common mistakes new fused glass artists make—plus tips on how to avoid them.
1. Mixing Incompatible Glass
Not all glass plays nicely together. If you fuse glass with different COEs (coefficient of expansion), it can crack as it cools—even if it looks fine at first.
✅ How to avoid it:
Stick to one COE per project (usually 90 or 96), and make sure all your glass is clearly labeled which COE it is.
2. Skipping the Cleaning Step
Oils from your fingers, dust, or leftover adhesive can cause devitrification (a dull, cloudy finish) or bubbles.
✅ How to avoid it:
Clean every piece thoroughly before firing—lots of glass artists use different types of cleaners. My preferred cleaner is Spartan window cleaner and handle with clean hands.
3. Firing Too Quickly
Rushing your kiln schedule can result in breakage, bubbles, or distorted pieces. Glass needs time to heat up, fuse, and cool down safely.
✅ How to avoid it:
Follow a tried-and-true firing schedule—and don’t skip the annealing step! Slower is often better, especially when learning.
4. Stacking Glass Too Thick
Too much glass in one area can create uneven melting or even overflow off the shelf.
✅ How to avoid it:
Aim for an average of 1/4" thick for a full fuse. Use a glass weight chart if you’re stacking unusually shaped pieces.
5. Placing Pieces Too Close to the Edge
Glass spreads as it melts. If your design is right at the edge of your shelf, it may drip off.
✅ How to avoid it:
Leave a small border around the edge—especially on full fuse designs—to give your glass room to move.
6. Not Understanding Color Reactions
Some glass colors contain metals that react chemically when fused together—like sulfur-based yellows reacting with copper-based blues.
✅ How to avoid it:
Read up on glass reactions (or run small test pieces first) to learn which combinations create unexpected effects—and which to avoid.
7. Not Testing New Designs or Materials
Jumping into a big project with a brand new type of glass, firing method, or mold can lead to surprises.
✅ How to avoid it:
Test first! Make small sample tiles or pendants before committing to a full-sized piece.
8. Forgetting the Kiln Shelf Prep
Glass will stick to uncoated shelves or mold surfaces if you skip kiln wash or fiber paper.
✅ How to avoid it:
Always prep your shelf or mold properly—kiln wash, ThinFire paper, or fiber will protect both your glass and your ceramic surfaces.
9. Trapping Air Bubbles Between Layers
Air bubbles can be a cool design feature when intentional — but more often, they're an unwanted surprise. Beginners sometimes stack glass in a way that traps large pockets of air between layers, especially when placing small pieces between two large sheets or creating sealed “pockets.” This can lead to distorted designs, uneven surfaces, or even cracked pieces.
✅ How to avoid it:
To reduce unwanted bubbles, avoid sandwiching small pieces inbetween two large sheets of glass. Conside using a bubble squeeze firing schedule when needed.
10. Expecting Perfection Right Away
Fused glass has a learning curve. Your first pieces might not look how you imagined—and that’s okay!
✅ How to avoid it:
Treat each project as part of the learning process. Even the “imperfect” ones teach you something—and often, they still turn out beautifully in their own way.
Final Thoughts
If you’re new to fused glass, don’t let a few bumps in the road discourage you. Every artist (myself included!) started with pieces that cracked, bubbled, or didn’t look quite right. That’s part of the process—and honestly, part of the fun.
The best way to get better is to keep creating. Try new things, ask questions, and celebrate the little wins. Every kiln opening is a chance to learn something new.