Heat Treated Glass

Which image shows a Fully Tempered glass, and which is a Heat strengthened glass? (A/B) If you answered A as a fully tempered glass, and B as heat strengthen glass then you are correct! Did you know that both are produced in the same tempering ovens and even heated to the same temperature? The difference is how fast they are quenched or cooled with air?

The difference between the two types of glass are as follows.

With tempered glass, the cooling process is accelerated to create higher surface compression in the glass of at least 10,000 psi. This is the process that makes the glass four to five times safer than annealed glass. As a result, tempered glass is less likely to experience a thermal break. With heat-strengthened glass, the cooling process is slower, which means the compression strength is lower at 3500-7500 psi. In the end, heat-strengthened glass is approximately twice as strong as annealed glass. Although heat -strengthen glass is not as strong as fully tempered glass, it has the advantage that glass fragments are more similar in size and shape to annealed glass fragments. The fragments tend to stay in the opening longer than fully tempered glass particles when broken which prevents the glass from falling in injuring someone.

 

Graphics by Guardian Glass