Why Your Heating Lamps Are Ruining Your Glass
Ever wonder why some batches of glass come out perfect, but the next one has weird internal tension or just snaps for no reason? Usually, it comes down to the kiln. Specifically, how the heat is hitting the glass. When you’ve got a row of IR lamps in one zone, you’re relying on them to act as a team. But if one lamp is pulling a bit less power than the one next to it, you get “cold spots.” In the world of glass, a couple of degrees isn’t a small deal. It’s the difference between a stable piece and one that’s a ticking time bomb of stress. The problem with “standard” lamps Here’s the thing: most standard IR lamps have a power tolerance of around ±5%. That sounds tiny, right? But in a massive annealing tunnel, it’s a nightmare. Imagine one lamp putting out 1100W while its neighbor is only hitting 900W. Your glass surface temperature starts bouncing around. You end up spending half your day fiddling with PID controllers, trying to “trick” the system into compensating for a few weak lamps in the line. It’s a headache you don’t need. That’s why we obsess over consistency. We tighten those specs so every single lamp delivers the same amount of heat. It just makes the whole process… quiet. Heat, power, and burnout Now, shortwave lamps are great because they react fast. You can ramp the temperature up and down with real precision. But there’s a catch. Pushing that much power into a small space puts a lot of stress on the lamp ends. This is where a lot of people get tripped up. You have to make sure your wiring and connectors can actually handle the current draw. If a connector is loose or under-rated, you’ll hear that snap, see a bit of arcing, and suddenly you’ve got a burnt-out lamp. A quick tip on replacements If you want your system to stay stable, stop mixing and matching. I know it’s tempting to just swap out one dead lamp with whatever brand you have lying around, but don’t do it. A different spec breaks the thermal balance of the entire zone. The best way to handle this? Replace your lamps in matched sets. It keeps the heat flow smooth and saves you from introducing new gradients that could wreck your glass.