How to Cut Glass Mirror

Are you planning on working with a mirror or glass on your next project? Then you’ll need to know how to cut glass mirror. Considering glass is one of the hardest compounds on earth, and it’s so prone to breakage, the idea of working with glass is scary for many people.

Fortunately, it is easier to cut glass than it may seem at first. Today, we’re going to cover how you can use some basic tools to learn how to cut glass mirror for your next project. By the time you’re finished with this guide, you should be feeling confident in your ability to cut glass.

What You’ll Need

When it comes to cutting mirrors or glass, you’ll only need a few hand tools to get the job done. Here’s what you’ll need:

Step I: Measuring For Your Project

Before we can get to the cutting part, you’ll need to measure the size piece of mirror or glass you’ll need for your project.

Use your tape measure to accurately determine the exact size mirror or glass you’ll need for the project. Then, use your straight edge and a marker to mark the surface of the glass.

Step II: "Cutting" the Glass

Now that you know exactly where you’ll need to cut, we can proceed to cut the glass.

Lubing Up

If you want to prolong the life of your glass scoring tool, you’ll want to lubricate the surface before you begin your cut. You can do this with kerosene or with glass cutting lubricant, which should be available at whatever store you purchased your glass scoring tool from.

Of course, if you’re working with a cheap glass scorer, or if you don’t anticipate doing too many glass cutting jobs in the future, you can skip this part.

All lubricating the glass will do is preserve the cutting edge of the glass scorer. In my case, I don’t bother, since I’ve only used my glass scorer a handful of times in the last twenty years.

But, if you like to keep all your tools in tip top shape, this guide on glass scorer maintenance has some great tips.

Anyway, let’s get back to the task at hand.

Clamp and Score

Bring the glass or mirror you need to cut over to your workbench (or a table) and set it down somewhere that you’ll be able to attach clamps to the glass. Next, grab a set of clamps and use them to hold down your straight edge at the line in the mirror that you’ve marked. Make sure the clamps are tight enough to secure the straight edge, but not so tight that they end up breaking the glass.

If you don’t have clamps handy, you can also just hold the straight edge down with your free hand. Now, grab the glass scorer with your free hand. You’ll want to apply firm pressure as you slide the glass scorer against the mirror.

If you’ve done this step properly, you’ll be rewarded with an absolutely horrible noise when you slide the glass scorer against the mirror. If you don’t hear anything, you aren’t applying enough downward pressure on the glass scorer. Just run the scorer along your line again until you’ve achieved that signature nails-on-a-chalkboard type sound.

Keep in mind that you can also press down too hard on the glass scorer. If this is the case, you’ll notice tiny pieces of the mirror chipping in the area where you’ve scored. You’ll want to remove any chips you see immediately by blowing them off the glass. Otherwise, they can damage the blade on the glass scorer.

Now you can remove the clamps and take the straight edge off your mirror. You should see a distinct scratch in the glass on the line you’ve just marked.

Step III: Breaking the Glass

Before beginning this step, you’ll want to put on some work gloves and safety goggles to protect yourself from any flying glass.

This next step is a bit of a leap of faith, and at first, it seems a bit scary. But, trust me, as long as you have a nicely scored line on your mirror, this is going to go exactly according to plan.

Put your mirror on the end of your table so that the line you’ve scored is directly over the edge of your table. Use one hand to secure the glass that’s on the table. Take your other hand and grab the glass that’s hanging over the edge of the table, and apply even downward pressure towards the floor as if you’re trying to break the glass (which is exactly what you’re doing).

The glass will then break exactly along the line you’ve scored, and you should be left with a perfect “cut.”

Step IV: Cleaning Up the Edge

While your edge should be perfectly straight, it’s likely to be a little rough. If you’re mounting the mirror inside a frame, the rough edge won’t matter, and you can skip this step. But, if the edge of the mirror is going to be exposed, you’ll need to sand and seal the edge.

You can quickly sand off the rough parts along the edge with a bit of 100 grit sandpaper. Once you’re finished, you’ll want to apply a mirror sealant to the edge to prevent the mirror from flaking at the edge.

Final Word

Learning how to cut glass mirror can seem like a tall order at first. Fortunately, it isn’t nearly as hard as it looks, and you can get the job done with a few simple tools. Be sure to wear gloves and safety goggles to protect yourself whenever you’re working with glass.

About Gus Donaldson

I built houses for over 30 years and recently retired. I've made lots of mistakes and hopefully teach you not to make the same ones. I still love to build and have a garage workshop that I use for hobby projects like the walnut bookshelf I made for my wife. I like to write and let people know that working with your hands and tools does not need to be intimidating.

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