Glass is commonly used for installation or repair on door and window inserts and in picture frames and other craft projects. Most of these require that you cut glass, but with so many different types of glass out there, you need to know the exact tool and technique you should use to avoid breaking the glass and that’s why we’re going to take you through a guide on how to cut glass.
To cut regular and mirror glass, you have to use a glass cutter to score the surface and then snap it in two. For glass tile, you should use a wet saw to achieve clean and accurate cuts, whereas tempered glass needs to be annealed before it can be cut.
In this guide, we’re going to teach you everything you need to know about how to cut glass, from the tools you have to use, to the step-by-step instructions you should follow.
Tools and Supplies You’re Going to Need
- Masking tape
- Permanent marker
- Cutting oil or kerosene
- Glass cutter, straightedge or steel ruler, and duct tape (for smaller pieces of regular glass)
- Variable-speed power drill with carbide-tipped glass-cutting drill bits (for cutting holes in regular glass)
- Wet saw and washable marker (for glass tile)
- Fine sandpaper, sharpening stone, or round file
- Kiln and glass cutter (for tempered glass)
- Work gloves and safety goggles
Broken glass is no joke. It should go without saying, but take the necessary precautions to ensure you’re working in a safe environment. Keep children and pets away from your work area, and don’t forget to wear work gloves to protect your hands from sharp edges, and safety goggles to prevent injury to your eyes.
The first stage of this project involves preparing your work area and getting your piece of glass squeaky clean. So, once you’ve found a large flat surface that won’t scratch your glass, such as a sturdy workbench or thick piece of plywood, you need to vacuum it to remove any dust, dirt, or debris that might be covering it.
We recommend covering the work surface with a thin, damp cloth to avoid any accidental damage to it and to create a non-slip layer for the glass.
Use a window cleaner and clean cotton rags to wipe both sides of the glass and remove any dirt or grit that can interfere with the tool you’re using. Make sure that your tool is clean as well.
Now, put your work gloves and safety goggles on, and let’s start cutting!
How to Cut Glass
The traditional method for cutting glass requires using an inexpensive tool called “glass cutter”. I know, pretty creative, right? The name, however, can be a bit misleading, as the tool doesn’t actually slice through the glass. Instead, this pencil-sized instrument scores the glass with a carbide- or diamond-tipped wheel.
Glass cutters are suited for scores up to 2 ft. long (60 cm). Longer pieces are more prone to breaking unevenly, so keep that in mind when choosing the tool for the job.
Here’s how to cut glass using a glass cutter:
- Place the glass on your prepped work surface and use a framing square, ruler, or tape measure to determine the length of the cut you need to make.
- Use a permanent marker to mark the cut. You can also mark the cut on a piece of white paper and place it underneath the glass, making sure that all the edges are in the right position.
- Dab cutting oil or a small amount of kerosene to lubricate the wheel, or simply dip the cutter into the oil. This will help you produce cleaner and more accurate cuts. Another option is to apply the oil to the specific area of the glass that you’re going to cut.
- Place a straightedge or steel ruler along the marked line to serve as a guide for the glass cutter.
- Secure the straightedge with two strips of duct tape to prevent it from shifting out of position as you score the glass.
- Hold the glass cutter as you would a pencil, and pull it toward you in one smooth glide. It’s crucial to keep the pressure constant to obtain a uniform score. If you’re applying the correct pressure to the cutter, then it’s going to sound like ripping silk. A gritty sound indicates that you’re pushing too hard and need to ease up. (Watch the video below these instructions if you want to hear exactly what the scoring should sound like.)
- Use the head of the glass cutter to elevate the glass, and hold it firmly with your hands on each side of the cut.
- Twist your wrists to break the glass along the score.
Now you just need to run a piece of fine sandpaper or a sharpening stone along the sharp edge left behind after the cut to dull it.
A final tip we can give you is to try to leave about 6 inches (16 cm) of glass on each side of the marked line to be able to grip it comfortably. If you want to cut a small piece of glass, you’re going to need another tool to break it off, such as pliers or a light hammer.
DIYers and sometimes stay away from projects that require a hole to be cut in glass, mostly out of safety concerns or simple lack of knowledge about how to do it. While there are certain things you need to consider, it’s not really a difficult endeavor.
To cut a hole in glass, you’re going to need a variable-speed power drill and a 1/8-inch or 3/32-inch carbide-tipped glass-cutting drill bit.
This technique works with regular glass, but it’s not suited for safety or tempered glass. In addition, attempting to drill these two types of glass will result in them shattering.
Now let’s get started on how to cut a hole in glass:
- Measure and mark the place on the glass where you want to make the hole. Avoid drilling within ¾ of an inch (6 cm) from any edge to prevent glass damage.
- Use masking tape to draw a large ‘X’ over the spot you’ve marked for the drill point. The tape will provide the necessary traction to prevent the drill point from slipping.
- Lubricate the drill tip with cutting oil.
- Set the tool at low speed, and drill a starter hole by aligning the point of the drill with the center or the marked spot on the glass.
- Remove the masking tape.
- Keep drilling at the marked spot at low speed, making sure to stop every now and then to clear the glass dust from the surface and lubricate the drill bit.
- Depending on the size of the hole you want to make, you might need to stop and replace the drill bit with the next size bit. Don’t suddenly switch from a small one to a significantly larger one, do it increasingly, instead, and make sure to lighten up the pressure on the tool with each bit change
- Drilled approximately ¾ through the glass thickness, and stop to turn the glass over.
- Start with the smallest drill bit again and repeat the drilling process at low speed.
But, first, don’t forget to smooth out the edges of the hole with a round file!
How to Cut Glass Tile
Glass tiles are a beautiful, durable material that’s commonly used for backsplashes and bathrooms accents. Like most types of glass, however, these tiles can be easily damaged and even shatter during installation.
There are several techniques you can use to cut glass tile, depending on the type of project you’re tackling. This time, we’re going to focus on teaching how to cut glass tile for large projects that require lots of straight cuts using a wet saw.
Using this tool allows you to achieve smooth cuts, as the saw releases a steady stream of water that helps reduce friction and cool the cut edge.
Before we start, we highly recommend creating a dry layout of your tile pattern so that you can make sure to palace them perfectly before attaching them to the wall. Also, don’t forget to position the cut tiles in those places where the sliced edges will be least noticeable, such as where the tile touches the underside of the cabinets.
Once you’re ready, this is what you should do to cut tile with a wet saw:
- Measure the place where you want to cut, and mark it with a washable marker that you can easily wipe away with a damp rag once you’re done cutting.
- Turn the wet saw on, and let it run for 15 seconds so the water starts flowing over the saw blade.
- Feed the glass tile through the wet saw by aligning it with the cutting guide on the saw.
- Cut along the marked line slowly, applying light and steady pressure.
And that’s it! Pretty easy, don’t you think? Just wipe away any remaining traces of the marker and your tile is ready to be installed.
Cutting tempered glass is tricky, as it can’t be cut using the same techniques as you’d use to cut regular glass without it shattering. Instead, to cut through a pane of tempered glass, you need to subject it to a process called ‘annealing’, which involves heating it to nearly 1,000 °F (538 °C), and then slowly cooling it to soften the tempered glass’ coating and weaken it.
Annealing should only be done if you have access to a kiln, and if the piece of tempered glass is smaller than 10 inches (25 cm) across. Otherwise, you’ll need to contact a professional glass cutter and hire them to cut your pane.
Take a look at what happens if you try to cut tempered glass with a glass cutter without annealing it first:
Now that you know why annealing is so important, let’s see how to do it:
- First, place the tempered glass pane in a heat-proof vessel and then cover it with warm water.
- Turn on the kiln to about 875 °F (468 °C), and soak the tempered glass until it reaches the temperature at which it will anneal. Depending on the size of the glass pane, the time it’ll need to soak will vary, but most types of glass will require about 30 minutes in the kiln.
- Cool the glass slowly to avoid excessively stressing it by lowering the temperature of the kiln to 800 °F (427 °C) and leaving the glass in for about 2 to 3 hours.
- Use a pair of tongs to remove the glass vessel from the kiln. Make sure you’re wearing thick gloves to avoid getting burned.
- Place the glass on a cooling rack and let it cool overnight. Don’t try to rush this step, because even if the outside of the glass feels cool, the inside might not be ready yet. Cutting hot glass is incredibly dangerous.
Once the tempered glass pane has cooled, you can clean it and use a glass cutter to make the cut.
How to Cut Mirror Glass
If you need a custom-sized mirror that’s no longer than 2 ft. (60 cm), you’ll see that, with the right tools, you can save quite a bit of money by cutting it yourself instead of having it professionally done. All you need is a glass cutter, and cutting oil.
After you’ve cleaned the mirror, this is what you should do to cut it:
- Lay the mirror with the glass-side up, and use a wax crayon to mark the place where you want to make the cut.
- Dab some cutting oil alone the line, and spread it with your fingers.
- Align a straightedge or steel ruler with the marked line to serve as a guide for the glass cutter.
- Secure the straightedge with a clamp or hold it firmly to prevent it from shifting out of position as you score the mirror.
- Pull the glass cutter toward you, holding the glass cutter like a pencil, to score the mirror. Keep uniform pressure and don’t backtrack or make multiple scores. (Watch the video at the very beginning of this guide to hear exactly what the scoring should sound like.)
- Position the score line along the edge of a table that’s longer than the mirror, and firmly snap the mirror in two.
Then, use 200-grit sandpaper to smooth the jagged edges, clean the mirror, and you’re done!
Learning how to cut glass might seem daunting at first. After all, broken glass is incredibly sharp and can be very dangerous if handled incorrectly. However, with the right protective gear and tools, you can easily get the job done yourself in most cases, without needing the help of a professional. In addition, you’ll be saving some money and learning new skills that could help you in the future.
Hopefully, you can use this guide to cut glass for your next DIY project safely!