2-Min Technical Tips: Understand How to Reduce Tempered Glass Defects
The dark colored spots visible with polarized sunglasses on car windows is a phenomenon called glass anisotropy. If you’re seeing similar defects in your glass products, watch this video! Uneven heating or cooling, quench movement and back lighting can all impact potential anisotropy and glass defects.
Watch our 2-minute technical video to learn how to identify tempered glass defects and understand how to prevent them.
Anisotropy is the stress or strain patterns in the glass that we see that commonly, we, we’ve always called it as iridescence. It’s caused by uneven heating or uneven cooling in the furnace of the quench. It commonly shows up, if you’re wearing polarized sunglasses, as dark colored splotches or spots.
Basically, what we want to do is have a lower convection temperature or convection fan speed. Lower furnace temperatures also help, lower oscillation speeds and randomness in the oscillation distance will help to reduce this differential stress in the glass.
If the problem is in the quench or if the iridescence shows up more in the quench as a quench pattern, which is the most common, normally the movement of the quench needs to be addressed.
The nozzle condition, the condition of the holes, the back-pressure slots; all of those items, which can affect the way the air impinges on the glass, need to be looked at.
The other issues like glass thickness, lighting conditions, viewing angle, elevation and even backlighting can also have an effect on the visual appearance of the stress pattern differentials.
We’re aware that anisotropy is “the latest buzzword” in the industry. Should you have any questions regarding this, please, give us a call.
If you are experiencing visual glass anisotropy and are looking for a solution, we’re here to help. Give us a call at 336-439-1715.