Fixing those annoying “Dead Zones” in Glass Annealing
Ever notice how glass containers with weird shapes—think deep bases, tight necks, or sharp shoulders—always seem to have those stubborn cold spots? We call them “dead zones.” The problem is that standard convection heating just doesn’t cut it. Air is lazy; it can’t squeeze into those tight curves. If you want the heat to actually soak in everywhere, you need short-wave infrared (IR) lamps. They don’t rely on air. They push heat directly into the glass. Getting the heat right When you’re working with borosilicate or soda-lime glass, you can’t just guess the temperature. We use high-wattage quartz halogen elements to get precise. By tweaking the voltage—switching between 230V or 400V, for example—you can control exactly how much heat is hitting the glass. Higher voltage is great because it lets you keep the equipment compact without losing the muscle needed to heat up those thick-walled sections. But be careful. If you cram too many watts into one tiny spot, you’re asking for trouble. You’ll end up with localized overheating or, worse, thermal shock. It’s a balancing act. The gear that actually works We use high-purity quartz envelopes. Why? Because we want the IR radiation to hit the glass, not get absorbed by the lamp itself. Depending on the job, we might use coated elements. This shifts the spectrum so the heat penetrates deep into the vessel instead of just scorching the outer skin. For the plugs, we stick with R7s or SK15 connectors. They’re simple, drop-in replacements. More importantly, they won’t melt your contacts when things get hot. Real talk from the shop floor Now, IR lamps are great, but they aren’t magic. They only work if your setup is dialed in. Check your reflectors. If they’re pitted or slightly crooked, you’re just trading one cold spot for another. And one last thing: these high-density tubes pull a lot of power. Double-check your wiring. Make sure it’s rated for the peak current, or you’ll be replacing burnt-out sockets right in the middle of a full-load cycle. Not a fun way to spend a Tuesday.