Stop choosing between a strong sheet and a clean print
Here is the struggle when you’re trying to temper and anneal glass right after silk-screening: it feels like a tug-of-war. You need enough heat to get rid of those internal stresses in the glass, but if you push it too far—or use the wrong kind of heat—your ink starts to burn or, even worse, the pattern just bleeds into a mess. We’ve found a way around this using short-wave infrared (IR) lamps in a continuous tunnel. Getting the heat where it actually belongs The beauty of short-wave IR is how fast it punches through the surface. Instead of just baking the top layer, it targets the glass substrate itself. If you’re using standard convection or long-wave heat, the surface temperature creeps up way too slowly. By the time the core of the glass actually hits the annealing point, your ink has already been cooked. It’s frustrating. But when you tweak the wattage and the spacing of the lamps, you hit that “sweet spot.” The glass relaxes, but the ink stays exactly where you put it. The heat density trade-off Now, if you want fast line speeds, you need high-wattage IR tubes. They pack a punch. But there’s a catch. All that intense heat puts a massive load on your conveyor’s cooling zones. If your cooling system isn’t beefy enough to yank that heat away the second the glass leaves the annealing zone, you’re looking at warped glass or a ruined finish. It’s a nightmare to fix. To avoid that, we use a staged cooling profile. It’s a gentler way to bring the temperature down without shocking the glass. Making it work on the floor In a real-world setup, you want these lamps wired into a zoned control system. This gives you a lot more freedom. Instead of one flat temperature, you can ramp things up in the first third of the tunnel and then slowly taper off as the glass heads for the exit. This creates a gradient that keeps the glass strength uniform across the whole sheet while keeping those silk-screened edges crisp and sharp. And a quick tip: stick with quartz-envelope lamps. They can take a real beating in a loud, gritty industrial environment, but they give you the most consistent output, day in and day out.