Fixing Those Pesky Cold Spots in Your Annealing Kiln
Ever pull a piece out of the kiln only to find it cracked because one specific spot didn’t get enough heat? It’s frustrating. We call those “dead zones.” They usually happen when the shape of your glassware is just too complex for the heat to flow naturally, leaving some parts of the vessel stressed and prone to breaking. To fix this, we use clear quartz infrared (IR) tubes. Think of it as a direct line of sight. Instead of just heating up the air and hoping for the best, these tubes beam radiant energy straight into the glass, hitting those tricky contours that usually stay cold. Why quartz? Because it’s practically invisible to short-wave IR radiation. The heat doesn’t get trapped in the tube wall; it shoots right through and hits the surface of your glassware. If you’re working with weird shapes, don’t just put one tube in. We set them up in multi-angle arrays. This way, the heat wraps around the piece. The neck, the base, the shoulders—everything gets hit at once, keeping the temperature steady across the whole thing. The nitty-gritty on power To get the kind of heat flux you need for fast annealing, these tubes run hot. Really hot. We use high-purity quartz because standard glass would just melt under the pressure of the filament. You can pick the lengths that fit your specific kiln, but keep an eye on your power. More wattage means more heat, but it also puts a bigger strain on your electrical setup. Double-check your wiring and breakers for that peak startup current. You don’t want to be smelling burnt wires in the middle of a run. A few things to keep in mind Here’s the catch: the more tubes you add to kill those dead zones, the hotter the outside of your kiln gets. You’ve got to find a balance between your IR lamps and your cooling system. If you cram too many heating elements in there without enough ventilation, you might fry your control electronics. And a quick tip for those irregular containers? Try a staggered layout. It breaks up the symmetry of the heat flow, which is actually a good thing. It makes sure no part of the glass is left out in the cold.