5 tips for better glass tempering
Apr 25, 2026
During glass processing, tempering can give glass strength and safety. But there are some small and easy overlook details in daily production can have a surprisingly big impact to the final result. This article runs through five practical tempering tips, covering heating control, shop floor temperature, drilled glass, and shaped glass. Put them to use, and you'll see better quality and efficiency.
1. Stage your heating - don't cook the glass unevenly
Inside a tempering furnace, heating usually happens in two stages: a fast ramp-up first, then a soak phase. If you don't manage this right, you get temperature differences across the glass. That kills flatness and weakens tempering strength. Setting up a smart heating curve is step one toward good quality.
2. Watch your shop floor temperature - it affects air pressure and cooling time
Tempering isn't just about what happens inside the furnace. The outside environment matters too. In winter, or any time your shop floor is cold, you can actually dial down the required air pressure and blow time. That still gives you good tempering quality, plus it saves energy. Win-win.
3. Drilled or slotted glass needs extra heating time
When glass has holes or slots, the heat path changes. The local thickness varies a lot, so you need to give it more time in the furnace. A good rule of thumb: add 2.5% to 5% more heating time compared to the same glass without holes. Skip this, and those areas can get too hot or too cold – leading to cracks or warping.
4. Pointed glass needs careful placement
If the glass has an angle smaller than 30°, heat builds up right at the tip. That can cause local overheating and distortion. For these pieces, shorten the heating time a bit. When you load them, point the tip toward the furnace exit. And here's a pro trick – sandwich some scrap glass pieces nearby as heat buffers. That keeps the pointed glass from sucking up heat too fast and warping.
5. Patterned glass needs a different heating strategy
The texture on patterned glass messes with heating uniformity. General rule: put the non-patterned side facing up. Then base your heating time and air pressure settings on the thickest part of the glass. That way the whole piece tempers evenly.
