Iam novice in glass tempering, only 3 years experience.
Recently we begin to have problems white white haze - a white abrasion on the bottom surface of the glass.
I know that are two reasons for this defect:
1. The glass is not flat at the begining of the heating phase.
2. The rollers are just clean and the contact betweem them and the surface of the glass is rough. Thicker glass increase this defect.
1. We ajust the settings and the glass stay flat during the heating phase.
2. We used SO2 gas according to the procedure described in the furnance manual: only during production, not on coating glass. The procedure say not to use gas excessively (to stop the injection when white haze disappear or when a bluish film is created on the surface of the glass).
But even we used SO2 gas (3 hours) the defect didnt disappear and the bluish film didnt form on the surface of the glass.
So, now I ask myself if is any gas in the recipient. The device shows that we have preassure and flow, but nothing happen. And I can not feel the smell. I know that SO2 gas smells like burned matches.
How can we check if the gas is ok? In winter we had -20 grd Celsius. Can low temperature desintegrate SO2 gas? How can we check if is any leak? How quicly the bluish film appears? 3 hours is not enough? I could not find pictures on the internet to make an ideea how it looks like.
Please help me in this matter with more information about the use of SO2 gas. The problem increase every day. First we had problems only with big sheets of glass, 8-12 mm, but now white haze appears also on 4-6 mm, small pices (400x1000 mm).