Glass Art Education

Glass Art Education is the learning hub at Art Glass Supplies, built for fusers, stained glass artists, and kiln workers at every level. The guides here explain how glass behaves on the bench and in the kiln, so you can plan projects with confidence instead of guesswork.

Know your glass: COE90 and COE96

COE stands for coefficient of expansion, a measure of how much glass expands and contracts as it heats and cools. Fusible glass is sold in tested systems such as COE90 and COE96, and every piece of glass in a fused project needs to come from the same system. Mixing COE90 and COE96 in one piece can cause cracking during cooling or stress that shows up later. Bullseye set the standard for COE90 and tests its glass for compatibility at its own factory, while COE96 covers a range of fusible brands sold as a compatible system. When compatibility matters, stay within one tested system and test a small piece first.

Cutting and shaping

Good cuts start with clean glass, a sharp cutter, and one firm score. Score once, then run the break with running pliers rather than re-scoring the same line. Grozing pliers nibble away small edges, and a grinder refines curves and tight shapes. Wear safety glasses whenever you score, break, or grind, and sweep the bench often so stray shards do not end up in your next project or your hands.

Fusing, slumping, and firing basics

Kiln forming happens in stages. A tack fuse joins pieces while keeping texture and relief, a full fuse melts a stack into a single flat layer, and slumping shapes already fused glass into or over a mold at lower heat. Every firing needs a prepared shelf, a controlled ramp, a working soak, and a slow anneal so the glass cools without locking in stress. Published firing schedules are guidelines, not guarantees. Kilns vary, and thickness, layering, and glass color all change how a piece behaves, so test a small piece first when the result matters and keep a firing log for your own kiln.

Surface treatments and decoration

Beyond plain sheet glass there is a whole layer of surface work: etched dichroic and etched luminescent patterns, glass paints, decals, frit, and stringers. Coated glasses such as dichroic and luminescent have their own handling rules, including which side to cut and whether to cap with clear. Our Etching & Firing Tips page covers those rules in detail.

Troubleshooting common problems

Most kiln problems trace back to a few causes. Cracks usually point to incompatible glass or cooling that ran too fast. Large bubbles often come from air trapped between layers, and cloudy or scummy surfaces suggest devitrification or glass that was not fully clean before firing. Slowing the schedule, cleaning thoroughly, and changing one variable at a time will solve most of these.

Keep learning

Every product page at Art Glass Supplies carries specifications and working notes written for that specific glass, and many include firing guidance and frequently asked questions. Bookmark this page, since we keep adding new guides and project ideas, and sign up for our newsletter for fresh tutorials and firing tips in your inbox.