Guidance of troubleshooting: How to get rid of white haze during glass tempering
Apr 18, 2026
White haze is the one of those optical defects you can frequently during tempering. At most time, it comes down to mechanical friction or heating parameters that just not set correctly. This guide walks you through what causes white haze – both lengthwise (in the middle of the panel) and crosswise (at the ends) – and what to do about it.
1.Lengthwise white haze - down the middle of the panel
When you see white haze running lengthwise through the center of a glass panel, it's usually a mix of two things: mechanical alignment issues and unbalanced heating.
On the mechanical side, common culprits include:
The equipment isn't level
Ceramic rollers have runout (they're not spinning true)
O-belts are slipping
The main shaft coupling keyway is damaged
On the heating side, look for:
Not enough heat balance pressure
The upper convection furnace temperature is too low
Glass oscillation speed is too high
The bottom of the radiant furnace is too hot
What to do about it
Start with the mechanical checks. Verify the equipment is level. Check each ceramic roller for runout. Make sure the bearing housings have enough high-temperature lithium grease. Inspect the O-belts for looseness or slipping, and check that main shaft coupling keyway for damage. Repair or replace anything that's worn or broken.
Now move to the process parameters. Increase the heat balance pressure and run time. Speed up the upper convection fans. Slow down the glass oscillation speed inside the furnace. And turn down the bottom radiant furnace temperature so it's not overheating the glass.
2. Crosswise white haze - at the panel ends
White haze showing up at both ends of the panel is usually a temperature curve problem. The most common causes are too big a temperature difference between the top and bottom of the furnace, or the bottom temperature being set too low.
Different furnace types also have their own specific causes:
Radiant furnaces: heat balance pressure is too high, and the run time is too long.
Jet convection furnaces: the upper convection fan speed is too fast.
