Dealing with the Headache of Cold Spots in Glass Tunnel Kilns
Most infrared lamps top out at a meter or two. That sounds like plenty until you’re running an ultra-long glass tunnel kiln. Suddenly, those little gaps between the lamps become a real problem. You get these annoying cold spots, which means your glass tempers unevenly and you end up with internal stress. It’s a nightmare for quality control. We figured out a better way: building custom continuous heating units that push way past that 2-meter mark.
The trick to length and power
You can’t just stretch a quartz tube and call it a day. If you do, the ends of the lamp run cooler than the middle because of the voltage drop. No one wants a “dip” in their heat profile. We spend a lot of time dialing in the wattage and voltage so the heat stays flat across the entire length. To keep things stable, we wire them in a series-parallel setup. If you just shove too much power into one long tube, you’re basically asking for a burnout at the connection points. Not a great way to start a shift.
Keeping the quartz from sagging
Here is the tricky part: quartz gets soft when it gets hot. A tube longer than two meters will actually start to sag under its own weight. If that filament touches the tube wall?**Pop.**The lamp is gone. To stop that from happening, we use heavy-wall quartz or specialized supports to keep everything centered and steady. Depending on what you’re making, we can tweak the coating too. Shortwave is great if you need to ramp up the heat fast. But if you’re working with thick glass and need the heat to soak deep inside, we’ll switch you over to medium-wave.
A few things to keep in mind
These long units cover a massive amount of ground, but they’re hungry for power. You can’t just plug these into a standard circuit and hope for the best. You’ll need to make sure your electrical panels can actually handle the load of a continuous array. And one more thing—these things put out an incredible amount of heat over a huge area. If your kiln’s ventilation isn’t up to the task, you’ll end up cooking your own wiring. It’s worth double-checking your airflow before you flip the switch.