Tempered safety glass can be temperamental. While there are many benefits to tempered glass, some of them have consequences. Here’s what you need to know about tempered glass.What is tempered safety glass?Tempered safety glass is made when a piece of regular annealed glass is put through a tempering furnace. It’s called safety glass because of it’s resistance to breaking, and because of the manner in which is breaks. Regular annealed glass breaks in big, sharp shards. Shards of annealed glass can be so large, that the force of their own weight can make them lethal. Tempering the glass makes it safer, because when tempered glass breaks, it “pops” breaking the entire pane evenly into tiny pieces. It might cut and scrape a person, but it’s not likely to sever an artery. You’ve probably seen broken tempered glass at the scene of a car accident. It’s used in the side and rear windows of cars to prevent serious injury during accidents.What are it’s properties?Tempered safety glass is much stronger than regular annealed glass. It’s impact resistance is up to 10 times greater, but it’s got a secret Achilles heel. The same principal that makes tempered glass so strong, also makes it’s edges very weak. While you could probably bounce a baseball off it’s surface, if you hit the edge with the same baseball, the pane would likely pop. This is the temperamental property I was talking about, it makes working with tempered glass very tricky business, and it’s responsible for making the glass impossible to modify in the field.
How’s it made?
To make tempered glass, you must know the exact size you need before you cut the glass. This is because once the glass has been tempered, it can no longer be modified. It can’t be cut, trimmed, drilled, or sanded. Once the piece of glass is cut, then it’s put into the tempering furnace, heated to 720 °C, and then quickly cooled.
Where do I need it?
Federal Law’s passed in 1977 require tempered glass in two locations. Any glass located within 24” of a doorway must be tempered. That includes, glass doors, glass windows in doors, and any glass above, or next to a door. The other place tempered glass is required is within 18” of the ground. Any pane of glass which extends at all below a point 18” off the floor must be tempered.
