DIY Guide to Cut Tempered Glass for Table Top

 Many people ask the question, what is tempered glass? Tempered glass is a type of glass that is toughened so it doesn’t break easily and even if it does, it will not shatter into shreds that could cause serious injuries. Instead, when tempered or toughened glass breaks, it crumbles into tiny pieces that are a lot safer.

Because this glass is toughened, it’s tough and tricky to cut. To cut the glass properly, you need to deploy certain methods and tools, if not, you might end up breaking the glass while making the cut. We have made a good outline for you to follow and cut tempered glass yourself for your table tops.

How to cut tempered glass

Necessary tools needed:

Here are the tools you’d need for preparing the glass and making your cuts:

  • Heat resistant vessel
  • A cooling rack
  • Tongs
  • Water (two cups)
  • A kiln for annealing
  • Thick gloves

Next, gather the tools listed below for cutting the glass:

  • Permanent marker
  • Safety goggles
  • Dowel (1/4 inch)
  • Ruler
  • Leather gloves
  • Coarse sandpaper

Prepare your glass:

Annealing is the trick used to cut tempered safety glass. If you don’t know the meaning of annealing – it is a heat treatment process that alters the microstructure of the glass in order to remove the internal stress and toughen the glass. You should start the process by using a kiln – the use of a kiln will help you make a cleaner cut and without a kiln you cannot safely cut the glass.


  1. Place the glass inside a kiln

The intense heat of the kiln will help soften the coating of the glass so it can be annealed. If you cannot afford to buy a kiln for just the purpose of cutting glass, you can simply borrow a kiln from a community college art department or any glass workshop near you (same applies to every other tool you’d need).

Note: process of annealing will toughen the glass and remove the stress points from the glass. It is only when these stress points have been removed that the glass can be safely cut and will not shatter or crumble while cutting.

2. Place the glass in a heat resistant vessel

You can get these heat-resistant vessels at a glass store or an art store. Place your newly annealed glass in the heat resistant vessel and cover it with 3 to 4 cups of water.

3. Allow the glass to soak inside the kiln for 30 minutes

This is an important part of the process as the kiln needs to be set at a temperature that is high enough to anneal the glass.

Use a temperature controller to help you maintain a constant temperature inside the kiln.

4. Cool the glass gradually

Cool the glass inside the kiln for about 3 hours. Here are the things you shouldn’t forget while cooling your glass.

  • You need to cool the glass gradually. Cooling at a too fast rate will cause the development of additional stress. This, in turn, weakens the annealed glass.
  • Don’t forget the importance of the strain point. During cooling, the strain point is the internal pressure that decreases inside a sheet of glass. Ensure the glass cools below the strain point so the glass doesn’t break.


5. Remove the tempered glass from the kiln

After cooling the glass, remove the glass sheet from the kiln. Use tongs to remove the glass, as it will still be very hot, and wear thick hand gloves when using the tongs and removing the glass.

Before you try cutting the glass, place it on a cooling rack, and leave it overnight. Don’t try to cut the glass while it is still hot as you might break the glass and even injure yourself.

Note: As the glass cools inside the kiln, the outer part of the glass will cool quicker than the inner part. Therefore, if the outer part feels cool, it doesn’t mean the glass is ready. Gradual glass cooling will help reduce any build-up of stress and will lead to a uniform cut.


6. Cut the tempered glass

Now, it is time to cut your glass to your preferred shape and size for your table top. Follow the below steps to ensure a successful cut.

  1. Clean the glass surface: clean the glass surface with windows spray and a clean cloth. Always clean your glass first to ensure a smooth and precise cut.
  2. Make a straight line with a permanent marker and cut the glass: After making the lines of how you want to cut your glass using a metal ruler and a marker, keep the ruler in place to give you a guide for cutting the glass. Now, place your glass cutter at the start of the line then move the glass cutter over the total length of the marked line. When cutting, press down moderately, never run the glass cutter along the line more than ones.
  3. Sand the cut glass. Use sandpaper to smoothen the rough edges. Skipping this step may cause injuries to the handler, always ensure you smoothen the edges for safe handling.

Note: place a dowel beneath the lines after scoring. This will prevent you from breaking the glass. Additionally, when cutting your glass, use both hands to apply equal pressure on both ends of the dowel. This will ensure a smoother cut.


Renowned misconceptions about using tempered glass

Tempered glass can stop bullets

This is a very serious and dangerous myth. While tempered glass may not shatter into pieces when a bullet goes through it, a bullet will certainly pass through. Bulletproof glasses are top level versions of protective and safety glass; it is much stronger than the tempered ones.

It is unbreakable

False! Tempered glass is sometimes called toughened glass but that does not mean it is unbreakable. Just like normal glass, toughened glass can break – the only difference is that you might require a larger force to break a toughened glass than you’d need to break the ordinary glass.


It is impossible to cut tempered glass

Shaping and cutting your glass should be the first step in the construction process and tempering the glass should be the last step. However, you can still cut this glass after using specialized tools and methods and converting to annealed glass.


Final thoughts

You should cut your tempered glass to your preferred shape and size first before annealing it because it is easier that way. Remember, to cut tempered glass, you need to anneal it for easy cutting and to avoid breakage.