Tempered glass, also called safety glass, is designed in such a way that it shatters into small pieces (not into shreds) when it breaks. Glass shreds can be very dangerous, but small pieces are a lot safer. 

Tempered glass may be hard to cut because it’s resilient and strong. It is prepared via thermal tempering which makes the glass harder and stronger than the conventional glass. The process causes compression on the outer surface and tension inside the glass. This is the reason that it shatters into small pieces, preventing accidents and injuries.

Tempered glass is used for various household and commercial purposes. It’s preferred in the architectural and decorative application of the house or apartment, due to its safety. It can often be found in shower enclosures, glass railings, windows, etc.

So, can you cut it and how? It can be rather difficult if you are a beginner but don’t worry. Here are a few steps to safely cut tempered glass. Continue reading these tips and we guarantee you will end up with accurate cuts.

Tools You Will Need

If you have decided to cut the tempered glass yourself, rather than using professional service, that’s a great choice for a few reasons. First of all, it will be cheaper and you can make any modifications without extra cost. Not to mention that you will be cutting tempered glass to your precise specifications and according to your needs. All you need is some tools to prepare and cut the glass. For preparing the glass, make sure you have:

  • Heat-resistant vessel
  • A kiln for annealing the tempered glass
  • Two cups of water
  • Work gloves
  • Cooling rack
  • Tongs

Here is the list of tools you will need to cut tempered glass:

  • Leather gloves
  • Safety goggles
  • Ruler
  • Glass cutter
  • Permanent marker
  • Dowel (¼ inch, never larger)
  • Coarse sandpaper (10-grit)

Preparing Tempered Glass

The process used to cut tempered safety glass is called annealing. It is a heat treatment method that changes the microstructure of the glass in order to make it easier to cut. Here is a simple guide to help you prepare the glass in the best way.

Make sure you start by using a kiln. This is very important since you can’t cut safely without it. Place the glass inside a kiln. The intense heat shall soften the coating of the glass and the annealing process can begin. If you don’t own a kiln, try borrowing one (you may find it in the art department at college, for example). 

The annealing process must remove the stress points from the glass, preventing it from breaking and making it safe to cut. Place the tempered glass in a heat-resistant vessel, which you can buy at many art and glass stores, then put the annealed glass in the container, and don’t forget to cover it with water. Let the glass soak for 30 minutes and we recommend you use a temperature controller.

Cool the glass gradually, for about three hours. If the cooling is too fast it may weaken the annealed glass. Remove the glass from a kiln once it is cooled, using tongs (it will still be extremely hot, so you should wear thick gloves).

The last step is to put it on a cooling rack overnight. Don’t cut it while it’s still hot, you may seriously injure yourself.

Cutting The Glass

Now that your glass is ready, follow these steps to successfully cut safety glass. Let’s begin!

The first step is to clean the glass. Don’t worry, tempered glass is very easy to clean with a simple window cleaner and a soft, dry cloth. Don’t forget to wear gloves and safety goggles. Your safety is the most important thing, so don’t risk injuries.

Draw a straight line with a permanent marker, using a ruler, keeping the ruler in place. This is the moment you should use a safety glass cutter. Place a wooden dowel (about ¼ inch) beneath the line. This important step will prevent the glass from shattering. Use both hands and apply even and sharp pressure on either side of the dowel. The glass will snap along the line.

The last step is to sand the cut glass. Use sandpaper to remove rough edges and prevent injuries. The glass will be safer and easier to handle.

Now that you know everything about safely cutting tempered glass, it’s time to grab your tools and get started! Consider inviting your friends over to help you, everything is more fun when you have company! You will be surprised how much money you will save by doing this on your own. But it also feels great to make something with your own two hands.