Stop Your Glassware from Shattering: A Better Way to Heat
If you’ve ever worked with glass, you know the dread of that sudden snap. You move a piece from a cold state into tempering or forming, the temperature spikes too fast, and boom—thermal shock. Sometimes it cracks right in front of you. Other times, it’s a ticking time bomb that shatters later. It’s a nightmare for your yield. The secret to stopping this is all about how you ramp up the heat. We use shortwave IR lamps to keep things under control.
Why speed actually matters
To keep glass safe, your heating system needs to react in milliseconds. Not seconds. Milliseconds. This is why we stick with shortwave IR lamps. They have very little “thermal mass.” In plain English? They don’t hold onto heat. If you use old-school resistive coils, they stay hot even after you flip the switch. But IR lamps? The moment you throttle the power, the output drops almost instantly. We pair these with SCR power controllers so you can dial the power from 0% to 100% on the fly. Instead of hitting the glass with a wall of heat, you can start low and slowly lean into it as the surface warms up. No steep temperature jumps, no cracks. Simple.
The “gotchas” of the hardware
Now, there are a couple of things that can trip you up. High-wattage IR tubes are great for fast cycles, but they’re hungry. If you’re running 2kW+ lamps, your wiring needs to be beefy. If it’s not rated for the peak current, you’ll get voltage drops. That leads to flickering lamps, which ruins your heating curve and puts your glass at risk again. And here is a big one:keep your hands off the bulbs. A single fingerprint or a smudge of oil on the quartz can create a hot spot. That little spot will eat through the tube and burn it out way before its time. We always treat installation like a clean-room job. It’s a bit of extra effort, but it’s the only way to make the lamps last.
Getting it right on the line
When we set up a preheating tunnel, the goal is total coverage. We position the lamps so the heat hits every inch of the glass evenly. If you have “cold spots,” the glass contracts unevenly, and you’re right back to square one. When it’s done right, the glass glides through the line, stable and ready for the final fire without any surprises.