Homemade Bulletproof Glass, Built and Tested

Hackers tend to stash away lots of stuff that seems useless, right up until it saves the day. This includes not just junk in our parts bin but brains full of tips and tricks for the shop. With that in mind, you might want to file away a few of the tips in [AvE]’s video of how he made bulletproof glass for a rainy day.

By his own admission, [AvE]’s video is a little disjointed, and the topic of the bulletproof glass is only covered at the beginning and again briefly at the end. Most of the video concerns the machining of a stout stand for the glass for testing on the range. There’s plenty to learn from the machining, though, and [AvE] is always good for a laugh, so the video is worth a watch. The bulletproof glass itself is part of a long-term project that [AvE] is releasing first to his Patreon patrons – a ridiculously over-built flashlight dubbed “The Midnight Sun”. His first two tries at laminating the Lexan discs were less that optimal, as both brands of cyanoacrylate glue clouded the polycarbonate. Stay tuned to the end of the video for the secret of welding Lexan together into an optically clear sandwich.

As for testing under fire, [AvE] sent the rig off to buddy [TAOFLEDERMAUS] for the hot lead treatment. The video after the break shows that the glass is indeed bulletproof, as long as the bullet in question is a .22LR. Not so much for the 9mm, though – that was a clear punch-through. Still, pretty impressive performance for homebrew.

If you want something that can stop an arrow, there’s a lot of materials science to be learned from the ancient Greeks.

35 thoughts on “Homemade Bulletproof Glass, Built and Tested

  1. Polycarbonate, Glass, Acrylic use all three in a sandwich with an epoxy, de-gas the epoxy with a vacuum pump and vacuum the layers in a vacuum bag. a 2″ layer 1/4 acrylic, 1/2 glass, 1/4 poly should stop most anything for at least one shot, several shots for handguns. There are also companies that will make custom glass sandwiches should you need quantity.

        1. I think he was suggesting that, as in most zombie movies, the real problem is other people.

          Also, some people use “zombie apocalypse” as a code word for “racial holy war.” :V

    1. Bulletproof is just short for high-energy projectile proof. And you might need that for all kinds of purposes and experiments not related to any guns or violence.
      Anything rotating at high speed for instance can get quite nasty if it goes wrong.

    1. Demo Ranch just did a video with a one inch think piece of titanium. Went all the way up to 50 BMG black tip armour piercing round. He does a lot of other videos testing armour plates and such. It’s quite interesting.

  2. Acetone welds polycarbonate and acrylic very well/clear (the hardware store kind, not nail polish remover). All you do is put a few drops on one sheet, press another sheet against it paying attention to press any air bubbles out. You only need to press hard enough to get the bubbles out. If you press it like he shows in the video it’ll probably squish out the plastic itself as the acetone is actually dissolving the polycarbonate/acrylic. Hold the sheets together until it sets (takes a few minutes). A book works well. I’ve used this method to construct robot chassis. You can also make a glue out of the polycarbonate/acrylic itself by dissolving it in acetone. This method forms very strong joints.

      1. Yeah acetone is cheap, and it typically comes in a 32+ oz can. That lasts indefinitely considering it only takes a few drops to make a weld. It takes some practice to get right so try it on scrap first. Super glue works too, but I found that acetone was more forgiving because it takes a little while to set. I also found out that super glue vapor bonds to the oil left behind by your fingers – as the glue dried the vapor caused perfect white raised reproductions of my fingerprints every everywhere I touched on the acrylic. Neat actually.

        Here’s an example that’s very similar to how I used it: https://youtu.be/qKHbKlq7aPg?t=1m29s

        If you’re careful you can make crystal clear joints (or bond sheets). I did some rudimentary tests and the acrylic breaks before the joint does.

      2. Acetone washes away the plasticizers so the joint is harder and more brittle than the base material.

        If you dissolve a bunch of the plastic and leave it in a cup to solidify, the piece that drops out is like glass – except on the inside where it’s porous. The acetone+plastic glue shrinks a hell of a lot when it dries, leaving a porous bubbly structure in between.

        Always cracks at the seams on me. That’s why I started doing heat welds instead of solvent welds.

  3. Isn’t part of the design of bulletproof materials based on alternating layers with different speeds of sound (a phonon equivalent to https://en.wikipedia.org/wiki/Dielectric_mirror ), high density and high breaking energy? If he’s solvent welding these sheets together it’s really no better than a thick piece of material and likely would just result in a plug of material being sheared out of the bulk. He would get much better results alternating plate glass and 1mm polycarbonate glued with a flexible adhesive.

    I think even better results are achieved with multiple thin air gaps that allow the intermediate fragments to diverge more quickly.

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