Whether you are buying glass for replacing windows, for a new glass table top, or for a shower stall, you are bound to come across the option of tempered or non-tempered glass. So what does that mean anyway? The differences between tempered and non-tempered glass are great and can mean the difference between a safe piece of furniture or home project and an unsafe one.
In the most basic sense, tempered glass is glass that has been treated to be four to five times stronger than untreated glass. This type of glass is used when the possibility of human contact is high. Tempered glass goes through a whole different process than non-tempered glass.
Specifically, tempered glass is cut to shape before it is treated. This is because, once treated, tempered glass cannot be cut or it will shatter into thousands of little pieces. This is the nature of tempered glass and it is a safety feature that makes it so popular. After the glass is cut to size, the edges are belt seamed or sanded to remove any jagged or sharp bits. Then, the glass slab is washed to remove any debris that may be left over. Finally, the glass is heated to almost 1200 degrees Fahrenheit and immediately cooled. This is what gives the glass its tempered effect.
A piece of tempered glass will be just as smooth and as clear as a non-tempered piece of glass, it will simply be treated with heat as described and stronger. Sometimes tempered glass will look or feel rough. This is common among poor quality tempered glass and is due to insufficient washing of debris from the sanding step. All glass that has been tempered correctly will be as smooth and as clear as untreated glass. In fact, the only way to tell tempered glass will be to look for the mandatory tempered glass stamp applied to each piece of tempered glass.
So why bother going through the trouble of heating and cooling glass? Because treated glass is much stronger and safer than non-tempered glass. Any glass that will be in human contact should be tempered. This includes windows, doors, shower enclosures, glass table tops and desks. When tempered glass is broken, it cracks into thousands of pieces rather than breaking into sharp jagged edges that can harm. Of course, this makes for a much more difficult clean up, but it is worth it for the safety component.
Nowadays it is almost impossible to buy non-tempered glass for home use. But it is still important to check for tempering in any glass that you purchase that is prone to come in contact with humans or animals. Never try to work with untreated glass unless you have been schooled on the nature of glass and are fully prepared for breakage. Knowing the difference between how tempered and non-tempered glass acts can mean the difference between danger and safety.