A Guide To Cutting Mirrored Glass

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It’s important to note that the term, ‘cutting mirror glass,’ is actually a bit misleading, since what you’ll be doing is more of a controlled break than a cut. This means that you’ll basically scratch — or score — the surface of your mirror, which will create a weak point in the glass. Then, after applying a bit of pressure along your scored line, you’ll get a clean break.

In order to cut mirror glass, start by cleaning the mirror with a glass cleaner, then use a wax crayon to mark the dimensions you want. Use your glass cutter to score the glass, and then snap the mirror in two with the help of a wooden dowel. Lastly, smooth down the jagged edge with sandpaper. 

Make sure you only cut mirrors that are shorter than two feet. Anything longer than that will be incredibly difficult to handle and might lead to inadvertent cracks or breakage. Let’s look at how you can cut mirror glass, which supplies you’ll need, and when you should hire a professional, so you can hang the right-sized mirror in your bathroom without shelling out hundreds of dollars.

What Supplies Do You Need?

The most important tool you’ll need to cut mirror glass (besides the mirror) is a strong glass-cutting tool (on Amazon). Most glass cutters are inexpensive and small, and you can easily buy a quality one for under $10.

They’re designed with a rolling cutter to score the glass, a balled tip to deepen the score mark, and a notched section to remove jagged glass pieces.

However, if you’re not comfortable using a glass cutter, you can use a steel file or a carbide scribe (on Amazon) instead. These are a bit more difficult to use than the rolling cutter and may result in a more jagged edge, but you can easily use them in situations where the edges of the mirror won’t show. 

Along with a glass cutter, there are several other supplies you’ll need to successfully cut glass:

How Do You Cut Mirror Glass?

Glazier measures the mirror

If you’ve never cut mirror glass before, then it’s advisable to visit a local framing or glass-cutting store and ask for a few pieces of scrap glass on which you can practice the cutting process before moving on to your final piece.

Once you’ve sufficiently practiced, here are the steps you need to follow: 

Prepare the Mirror

Before you start cutting mirror glass, make sure you have a flat work table that’s large enough to hold the entire mirror. Then, cover your work surface with a soft material to absorb all pressure. Lay your mirror, glass-side up, on the soft material, and remove any debris or dust from its surface with a glass cleaner.

Mark the Dimensions You Want 

Next, use a wax crayon on the mirror to mark the width and length you want. Pour a bit of mineral oil on top of these lines, and then use your fingers to spread the oil until there’s a thin layer coating the surface of your mirror. This layer of oil will ensure that the cutter remains cool while it scores the glass. 

Position and Secure the Ruler

Place and align a straightedge ruler along the marked line. However, make sure that the ruler is longer than the mirror. Then, grip it firmly, or simply secure it with a clamp, as the smooth surface of the mirror can cause it to slip.

Score the Glass

Next, take your rolling cutter, dab a few drops of mineral oil on its tip, and position it against your ruler. Apply firm, controlled pressure, and then pull the rolling cutter from the far end towards you. Make sure you use just enough pressure to leave a solid mark on the mirror, but not too much that it breaks the glass. 

Make sure you avoid backtracking or making multiple scores, as this could lead to a jagged break. Instead, cut only in a single direction and listen for a crackling sound as you score the mirror. 

Deepen the Cut

After making the line, use your glass cutter’s ball end to gently tap the glass along the score mark to further deepen the cut.

Break the Mirror

Before snapping your mirror into two, place a wooden dowel directly under the score mark, making sure that the dowel is longer than your mirror. Then, using one hand to hold one side of your mirror steady, firmly press down on the other side with your other hand. 

This should snap the mirror into two clean pieces. However, if you see any jagged pieces, remove them with the notches of your glass cutter. 

Sand the Edge of Your Mirror

File your mirror’s jagged edge with 200-grit sandpaper until it’s completely smooth and perfectly safe to handle. Make sure you also clean your workplace thoroughly, as there might be tiny slivers and shards of glass lying around. 

It’s best to clean the area with a wet paper towel and a vacuum to ensure you’ve cleaned up all the stray and hard-to-see pieces.   

Safety Tips to Keep in Mind

Worker cutting the surface of glass mirror

You can never be too safe when working with glass. So, to prevent any serious injuries or accidents, here are a few important safety tips to keep in mind:

Avoid Damaged Mirrors

Make sure you don’t try cutting mirrors that are severely cracked or chipped in multiple places. This is because a damaged mirror might not be able to handle the cutting process and may even shatter while you’re working on it. 

Practice First 

It’s better to buy a few pieces of inexpensive mirror glass on which you can practice and perfect your mirror glass cutting skills. Try starting with single-strength window glass, as it’s usually extremely cheap and easy to cut. 

Wear Protective Gear

It’s important to note that the breaking and scoring process will discharge tiny slivers of glass, which could potentially enter your eyes. For this reason, it’s extremely important to put on a pair of safety goggles whenever you’re working with glass. 

It’s also advisable to wear a pair of protective gloves, especially when you’re handling freshly-cut glass, as the edges will be incredibly sharp.

Should You Hire a Professional?

You don’t need to hire a professional if you’re cutting glass for smaller DIY projects, such as filling a frame or adding a few more facets to a simple rectangular sheet.  

However, if you have a piece of glass that’s longer than 24 inches, then it’s often best to hire a professional. This is because scoring and breaking such a large surface will be extremely difficult, not to mention dangerous, for anyone who’s not properly qualified for the job. 

Similarly, you should also hire a professional if you want to cut anything less than half an inch in size, as the restricted workplace significantly increases the risk of cutting yourself. 

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