Making Bulletproof Wood [video] | Hacker News Reader

Making Bulletproof Wood [video]

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Regarding the interior of the wood not being soaked by the stuff when it was cut open. (35:32) I suspect moisture content of the wood is a factor. A similar challenge is faced when cooking French toast, with particularly thick slices of bread. When making French toast, you want the custard to fully soak the bread, but a similar effect occurs if you use moist bread, where the middle is not soaked as well as the outside, it looks almost exactly like that cross section of the wood in the video. The solution is to leave the sliced bread out overnight, to allow the moisture that is filling all the capillary fibers to dry out. Then you can make perfect French toast because the dry capillary fibers are much better at sucking the custard in to the center, like a bazillion little straws.

Thus, I suspect drying the wood ahead of time would help?

P.S.: on the thickly sliced French toast, to get it cooked evenly inside with a nice exterior crust, after custard saturation (don't overdo it) I recommend searing the slices quickly in a pan with butter, then throwing in an oven at 350degF for 3-4 minutes. My custard recipe per serving is approximately 1 cup dairy, 1 egg, 1 tablespoon of honey, and a little pinch of salt. Briefly zap the honey in microwave to make it easier to mix.

Thanks for explaining that! I didn't know why I was having the problem, even after soaking the bread in custard for a long time!

are you using the whole egg or just the yolk for the custard?

Either works - adding only yolks yields a richer custard I think, but it's my belief that the albumen carries some important quality to the end product - somewhat mysterious, but anyway I usually use the whole egg. I sometimes throw an additional yolk or three in there if I'm feeling luxurious, exactness is not key to the ratios. If you mix the custard the night before too it develops a lovely flavor profile by morning.

You can also skip the searing in a pan step and just bake all of the soaked slices in a casserole dish in the oven for bread pudding :)

I wonder if soaking it in a vacuum pot would help, similar to how a lot of epoxy craft people do it.

There are two potential issues that I wish he either explored or explained in more detail:

1. When he cut the post-treated wood and the middle looked very much like untreated wood. He kind of glossed over that and explained that he thought the chemicals were penetrating all the wood, but that shot looked really suspicious. I’d be surprised if the chemicals were really effective for that thick of a piece with only one soaking (which left a very dirty by-product by the way, suggesting the solution’s effectiveness may have deteriorated before it had time to work on the innermost part of the wood).

2. There didn’t seem to be any bullet-stopping until he decided to glue more than one piece together with a fairly strong glue. And oddly enough, the bullet seemed to stop near the boundary between pieces that had been glued. I’m sure the wood was strong, but how do we know the glue itself wasn’t a substantial barrier stopping the bullet? I can imagine many very thin slices of untreated wood with enough glue interfaces binding them together (depending on the glue) also potentially stopping a bullet.

In either case, it was a cool experiment and looked like it took a lot of time to pull off.

It actually did really well with just his one original panel. The back would have been completely blown out if it exited fully expanded at a high velocity.

I agree with your treatment observation and believe that shows room for improvement.

I suspect the benefit of the multiple layers was mostly from the different grain orientations stopping the splintering. I agree that more layers of thinner boards would have performed better, but I'd wager this would hold true even for the weakest of glues, or no glue at all.

That's some amazing amount of effort! I was hoping to see him contact the authors of the paper to get their comments on his methods, and in particular on the seemingly incomplete chemical treatment shown in the cut block.

He could try starting with e.g. 3x thinner blocks to ensure chemical treatment reaches the core, and then glue 3 of those together to end up with the same thickness as his single layer. Curious to see the bullet performance of that.

He even mentions that the paper found that treating the wood for longer lead to worse results. That combined with the incomplete treatment of the middle leaves me suspicious how much the chemical treatment really contributes, compared to just compressing and heating wet wood.

Another curious material if ballistic protection is your fancy, is fiber reinforced closed cell foamed concrete at a proper density and thickness.

While not suitable as personal armor due to thickness (generally around 1.5ft/45cm), it’s something can provide rapid and cheap local access to protection from shrapnel and rifle bullets, which unfortunately is still a genuine concern around the world.

At lower density foamed concrete also makes for good insulation that doesn’t have the toxic offgas and flammability problems of petrochemical foams.

my back of the napkin math only puts this around the same stopping power as plywood of similar thickness. Sand bags work a lot better and are a hell of a lot easier and cheaper to produce

A 45cm thickness of plywood would be an enormous amount of plywood, unless you're only covering a very small area.

From my experience shooting plywood, the 9mm would have no problem going through the same thickness. He is legitimately on to something with his process.

A 9mm would get through 45 centimetres of plywood???

Nilered didn't use 45 centimeters of densified wood, he used maybe four centimeters of it.

What are you on about. 45cm is INCREDIBLY thick, and a solid plywood block of that thickness will probably stop high caliber rifle bullets.

I've used telephone books as backstops in the past and abour 3-4 of them is enough to stop a handgun bullet easily.

We use 10mm mild steel plates for targets, and they don't even dent when shot with a 9mm round.

What are anybody in this thread on about with 45 centimeters? He stopped a 9mm with about four cenitmeters. Skip to 53:00

You are literally replying to a comment thread where OP said [about plywood] "While not suitable as personal armor due to thickness (generally around 1.5ft/45cm)"

Did you skip that entire part of the conversation and just went to the final comment in the tree?

Spacebacon said:

> From my experience shooting plywood, the 9mm would have no problem going through the same thickness. He is legitimately on to something with his process.

He's obviously talking about nilered's result. I have no idea what you people are on about with 45cm, 45cm of anything besides styrofoam will stop a bullet.

I have no idea how you read this comment thread and conclude that obviously he's talking about nilred's result and not the comments he was replying to. It's not obvious at all, in fact I don't know how you arrived at this conclusion.

I have no idea how you could read spacebacon's comment and conclude that he believes damn near half a meter of plywood would be insufficient to stop a 9mm bullet. That's so absurd it should have stopped you in your tracks and had you reevaluate what it was spacebacon was saying. How can you seriously believe he was claiming to have experience shooting at half a meter of plywood? The very premise is absurd.

Either spacebacon is completely insane, or he was talking about nilered's video. You chose the 'he's insane' interpretation. I say you're obviously wrong.

When you say "his process", you're talking about nilered's process right?

Plywood rots unless protected. But if you're going for engineered solutions then plywood layers spaced apart with something a bit more flexible/compressible would be more effective and possibly lighter than a solid block of wood.

https://shocklayer.com/blogs/news/bulletproof-material-under...

Would a wet sandbag have more stopping power than a dry one? Or does that reduce the sheering strength?

Water is very effective at stopping bullets, so I would assume so.

What I am talking about is a concrete based foam, with small fiber reinforcement. Basically a bullet catch, that uses space to slow things down, rather than the harder job of stopping it outright. The 45cm number is if one uses a very low density mixture, since it’d be best used when space isn’t a concern. So it’s actually somewhat comparable to styrofoam, but doesn’t burn. That said, there is a wide range of potential mixtures, ranging anywhere from straight concrete to pure foam, so one can increase the density, and make it more compact, but it’s about what you are optimizing for. So that yes the actual capabilities of whatever is being referenced will be a bit confusing unless density is explicitly mentioned. A big prefabricated slab of what I am considering is human movable, and everything needed for on site application fits in a pickup truck. Not quite suitable for frontline application, but would be a great option for those in defensive positions farther back.

Something as simple a spraying a few to several inches some over a tarp would offer huge overhead protection from things like drone grenades or suicide drones in a trench, were implementing wood and sandbags isn’t as widely viable as just dropping a slab that supports it’s own weight.

At 45cm thick, I would hope it will be protecting me against shells, not just rifle bullets...

That’s not really what I’m proposing. It’s not solid concrete, it’s a concrete based foam, with small fiber reinforcement. The point is it’s quite lightweight, both the materials and finished pieces are movable by people without heavy equipment outside of a pickup truck.

Basically it requires a small portable cement mixer, a foam generator and a pump. As an example, one could layer it over defensive fortifications rather quickly, or fabricate human movable slabs which could be placed over trenches. It can even potentially even on vehicle roofs/sides, providing some degree of protection from drones grenades and suicide drones.

Even a fucking tank isn’t going to protect you from a direct artillery shell hit.

45cm of almost anything with similar density will provide suitable protection. Sand bags, bricks, wood, glass, paper etc.

"Computer Shopper" magazines made for great backstops when zeroing scopes in a .22lr rifle.

I suspect layering paper with a squishy resin in multiple layers would be very effective armor. Is paper close enough to call it "from wood"?

Layering paper and resin makes a material called “Micarta” which has been around for awhile.

til: https://en.wikipedia.org/wiki/Micarta

that appears to be pressure injecting resin so it blends with fibers and makes a solid. Early reinforced bakelite.

I'm thinking layers of interleaved paper and a resin. Free to move internally, slightly; with some fluidity remaining in the goo. It'd need a hard shell layer too but im thinking "spiderweb" shock resilience might come from the fluid component.

like Air between the pages of the magazines.

My grandfather was a gun smith and he hated going outside in the winter to test out guns so he had a thick stack of old phone books in his basement outside his gun room and he'd fire into them semi regularly while building/repairing guns.

Those phone books would easily stop even semi 'serious' rounds.

What is missing is comparing against other types of wood of same weight, some wood floor laminates, or the same food without treatment for example.

It looks like the wood after treatment is not much better than the same weight of plywood.

Testing Penetration With 30 Layers of Wood: 9mm vs. .357 Sig vs. .45ACP https://www.youtube.com/watch?v=j4EeZUPDaNc

How much wood will a 9mm bullet go through? https://www.youtube.com/watch?v=9A6ZLDEooEk (full metal jacket 9mm 115 grain is not going trough 4 inch plywood).

how many 2X4s does it take to stop a bullet? https://www.youtube.com/watch?v=1-rTvzHQa1Q (answer 4)

He did the comparison at the end of the video no?

Ah. He did against the same wood.

YouTube has been pushing me this video all day. I guess we’re all in the same “hacker” algorithm bubble

This channel is one of the "positive outliers", since it's gained popularity amongst many people worldwide even outside of science minded people

Another observation about the band saw cut...

I don't think that was an indication of weak penetration into the wood. The solution did not darken until later in the process and that means it was penetrating back into the material after it had changed color.

It seems there was a conflation of two expectations. The first being a material so hard that bullets just bounced off of it. The second being a material so effective at dispersing energy that bullets could not penetrate it. Kevlar is the well known example of the second category. In the end, the compressed wood seemed to improve a little in both categories, but not much. For reference from the video the same bullet that was stopped by 7 untreated boards of wood only required 3 treated pieces.

I was disappointed that the 7 untreated boards were not glued together.

I hate to rain on his parade, but as a bulletproof material that stuff is effectively worthless. An equal density of plain transparent polycarbonate has substantially more ballistic resistance, and is far easier to make and mold to shape. The same can be said for equal densities of steel, aluminum, magnesium, titanium, etc.

However... As a material for musical instrument construction, that hyper-densified wood might be very interesting.

It was never about practicality, it's more about the interest and whether it can be done.

Otherwise just go buy a normal bulletproof vest and be done

exactly. this is the same guy who bought lab grade reference materials to make a cookie. Think that cookie cost thousands. Where as you can follow the recipe off the back of a bag of chocolate chips and get a better cookie for cheaper. He knows it. He is just playing around with fun things.

Hmm. I wonder how a violin made out of hyperdense wood would sound like, especially if you used a custom mold for each section so that it was perfectly fitted together?

Or maybe the front plate of an acoustic guitar? I bet the density would mute the highs a little but then the rigidity would increase the overall projection.

Great video but I was more interested in the aspect of using this high-density wood structurally instead of steel for example. It would be nick to see some examples to that

This may interest you: https://www.washingtonpost.com/climate-solutions/interactive...

I would have liked to seen a baseline comparison against just a regular piece of denser hard wood like ebony, bull oak or lignum vitae

I guess if your goal is to bloat up a video until it's an hour long, then you have to add a segment about how to open a crate. Then literally show a video of reagents dissolving.

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