How to Cut a Tempered Glass Screen Protector

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To be honest, cutting tempered glass is exceptionally difficult and you’re very likely to break your screen protector if you attempt to do this. Tempered glass is made by heating regular glass to high temperatures and cooling it while applying pressure to compress the glass and strengthen it, which makes cutting it exceptionally difficult. You could theoretically use an annealing machine to un-temper the glass or use a laser cutting machine, but this involves buying thousands of dollar’s worth of equipment all for a simple screen protector. If you can’t simply return the old screen protector or replace it, there are two options that may work when it comes to cutting a tempered glass screen protector.

Things You Should Know

Method 1
Method 1 of 3:

Sizing the Protector for Your New Phone

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  1. Take your screen protector and place it flat on your table or desk. Set the phone down upside down on the screen protector. Line the edges of the protector up so that they’re parallel with the edges of your phone to make cutting easier.
    • If you’re cutting the screen protector to put it on something other than a phone, simply measure the dimensions and draw them on the screen protector.

    Warning: Just as a reminder, the odds are high that your screen protector will shatter when you try to cut it. You can attempt to use either of these methods, but you’re better off just buying a new screen protector if possible.

  2. Grab a fine-tipped permanent marker. Without touching the edges of your phone, carefully outline the phone using the edges as a straight edge. Keep the plastic part of the marker against the phone to avoid getting ink on it. Cover the entire outline of your phone to transfer the size you need to cut on to the screen protector. [1]
    • Add a small notch at the bottom by hand if you have a home button. This notch will be a lot harder to cut out, though.
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  3. Regardless of how you are cutting the tempered glass, it’s important to take the proper safety precautions to avoid cutting yourself. Grab the thickest pair of gloves you have, throw on a long sleeve shirt, and get some protective goggles to keep your eyes safe. [2]
    • If you’re cutting the glass underwater to reduce the amount of stress on the glass and minimize the odds that it shatters, you probably don’t need to protect your lungs. If you’re going to trim the screen protector down with a diamond file though, you definitely need a dust mask or respirator to avoid inhaling the dust from the glass.
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Method 2
Method 2 of 3:

Trimming the Protector Underwater

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  1. Grab a container that is large enough for you to submerge both of your hands, your screen protector, and a pair of scissors. A 12 by 12 in (30 by 30 cm) box should be big enough if you have something like that. Fill the bucket up ¾ of the way using warm water from your tap. [3]

    Warning: This process may not work if you have a thicker screen protector. This process is best for thinner versions that have a little bend in them. This style of screen protector isn’t usually 100% tempered glass, which makes it easier to cut.

  2. A pair of craft or kitchen scissors probably won’t work for this. Grab a set of strong scissors with sharp blades. Hold the scissors in your dominant hand and submerge them underwater with your screen protector in the other hand. Hold them 2–3 inches (5.1–7.6 cm) below the surface. [4]
    • Don’t take your gloves off to do this. It may feel weird wearing gloves in water, but it’s a key part of staying safe!
  3. Start on any side of the screen protector. Hold it steady and keep your nondominant fingers at least 2 inches (5.1 cm) away from the cutting line. Carefully cut along the line that you drew on the permanent marker. Go really slow to ensure that you don’t put too much pressure on the screen all at once. [5]
    • It is thought that the water makes it easier to cut the glass by providing a cushion for the glass as you’re cutting it, which it reduces its overall strength and makes it easier to cut. Some people even compare the feeling of cutting glass underwater to cutting cardboard! [6]
  4. Once you’ve trimmed the first side down, turn the screen protector to the next edge and cut the next side out. Repeat this process for the remaining sides of the screen protector. Cut slowly and work carefully to ensure that you don’t shatter the screen. [7]
    • If you have a notch for your home button, use the portion of the blades that are closest to the handle, not the tips.
  5. Pick up a diamond file or dremel tool with a buffing tip. Use the flat side of the file to scrape each side of the screen protector using gentle back-and-forth strokes. Do this 10-15 times for each side to smooth the cuts out and remove any loose shards. If you’re using a dremel tool, hold the buffing tip underwater without submerging the tool itself. Turn the tool on and run the tip around the edges of the screen to buff it out. [8]
    • A diamond file is basically a long piece of metal with a textured edge use for sanding hard materials.
    • Diamond files have different grits, just like sandpaper. Use the finest grit you possibly can to do this.
    • A dremel tool is a small, pen-like power tool with a tip that spins. It’s used to trim materials down without cutting. If you use a dremel tool, only submerge the rotating tip in the water to avoid shorting the tool or electrocuting yourself.
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Method 3
Method 3 of 3:

Filling Tempered Glass

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  1. Lay a sheet of cardboard down near the edge of a table. Put your screen protector on top of the cardboard and hold one of the edges you’re filing 1–2 inches (2.5–5.1 cm) off of the table. Place another sheet of cardboard on top of the screen protector to keep shards of glass from flying everywhere if the screen breaks. [9]

    Warning: This is not a good idea if you need to remove more than 1 ⁄ 4 – 1 ⁄ 8 inch (0.64–0.32 cm). This process will work if you’re trying to remove a small amount of glass to make a screen fit better, but it will eventually shatter if you remove too much glass.

  2. Get a diamond file in the finest grit you have access to. Brace the top of the screen gently with your nondominant hand. Then, hold the file flat against the side you’re sanding down. Slowly and carefully move the file back and forth. It may take 2-3 minutes to remove enough glass to reach the line you drew on the screen protector. [10]
    • You have to be very delicate while you’re doing this. If you apply too much pressure, the screen protector may shatter.
    • You could theoretically use a dremel instead of a diamond file for this, but it will take a lot longer since you can only work in 1 ⁄ 2 inch (1.3 cm) sections with the small dremel bit. Your line likely won’t be as clean either.
  3. Once you’ve filed down your first side, lift the cardboard up and rotate your screen protector so that a new side rests 1–2 inches (2.5–5.1 cm) over the edge. File this side down the same way you did the first side. Repeat this process for each of the additional sides until you’ve removed all of the excess glass. [11]
    • You don’t need to sand the edges down since the diamond file is basically doing this for you as you remove the glass.
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      Warnings

      • You are highly likely to shatter the screen protector if you do this. It may work, but any attempt to cut tempered glass may simply lead to the entire screen cracking. [12] It’s much safer to just get a new screen protector.
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      Things You’ll Need

      Sizing the Protector for Your New Phone

      • Permanent marker
      • Thick gloves
      • Dust mask or respirator
      • Protective eyewear

      Trimming the Protector Underwater

      • Bucket
      • Water
      • Scissors

      Filling Tempered Glass

      • Cardboard
      • Diamond file

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      Expert Interview

      Thanks for reading our article! If you’d like to learn more about glasswork, check out our in-depth interview with Douglass Brown .

      References

      1. ↑ https://youtu.be/zKcIhZCCaSk?t=194
      2. ↑ https://youtu.be/VJBZsAewU-A?t=67
      3. ↑ https://youtu.be/3mMVerSJ9mA?t=72
      4. ↑ https://youtu.be/3mMVerSJ9mA?t=114
      5. ↑ https://youtu.be/3mMVerSJ9mA?t=114
      6. ↑ https://youtu.be/usZ8MQzbglk?t=130
      7. ↑ https://youtu.be/3mMVerSJ9mA?t=122
      8. ↑ https://youtu.be/3mMVerSJ9mA?t=191
      9. ↑ https://youtu.be/VJBZsAewU-A?t=102
      1. ↑ https://youtu.be/VJBZsAewU-A?t=117
      2. ↑ https://youtu.be/VJBZsAewU-A?t=117
      3. ↑ https://www.nytimes.com/2009/07/07/science/07glass.html

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