Fixing the “Cold Spot” Problem in Glass Tunnel Kilns
Most infrared lamps stop at about a meter. That’s fine for small jobs, but if you’re running a massive glass tunnel kiln, it’s a headache. You end up stitching together a dozen small lamps, which leaves these annoying “cold spots” every time one lamp ends and the next begins. We figured out a better way. We build custom short wave infrared (SWIR) heating units that stretch past 2 meters. No gaps. No cold spots. Just one long, steady line of heat. The tricky part about going long You can’t just stretch a quartz tube and call it a day. If you do, the filament in the middle will either sag or just burn right out. To stop that from happening, we tweak the voltage and wattage. We usually bump up the voltage to keep the current steady across the whole length. It’s the only way to make sure the heat feels the same at the two-meter mark as it does at the start. If that voltage dips, your glass heats unevenly. And we all know what that means: internal stress and shattered glass. Dealing with the physics We use high-purity quartz to hold the tungsten filament, but when you go this long, the tube becomes a bit more fragile. It’s under more mechanical stress. To keep things from snapping during installation or when the metal expands from the heat, we use reinforced end-caps and connectors that actually fit tight. As for the heat itself—short wave radiation is really the only thing that can punch through thick glass quickly. If you need a specific wavelength, we can add coatings to the quartz. Just a heads-up: that usually costs you a little bit of total heat output. What to watch out for The best part here is the footprint. You get a smooth, continuous thermal profile across your entire tunnel. It just works better. But there’s a catch. A two-meter, high-wattage unit throws off an incredible amount of heat. A lot of it hits your kiln walls. Before you drop these in, double-check your cooling system. If your fans or vents aren’t up to the task, you might find your chassis warping under the pressure. It’s a powerful tool, so you’ve got to make sure your frame can handle the sweat.