[Chilinot]

This seems to be the research behind it: https://www.fpl.fs.usda.gov/documnts/pdf2018/fpl_2018_song00...

And there are only smaller comparisons towards steel. They are more focused on how it compares to regular wood.

In summary, what they are doing: 1. Boil the wood. 2. Press the wood. 3. Done.

[enopod_]

This seems to be the original research paper: https://www.nature.com/articles/nature25476 [edit: whoops, it's the same paper]

"First, natural wood blocks were immersed in a boiling aqueous solution of mixed 2.5 M NaOH and 0.4 M Na2SO3 for 7 h, followed by immersion in boiling deionized water several times to remove the chemicals. Next, the wood blocks were pressed at 100 °C under a pressure of about 5 MPa for about 1 day to obtain the densified wood"

Pretty simple and straightforward.

[scythe]

The real question for practical purposes is how much of these fine chemicals are actually consumed during the process and how much can be reused. The foul-smelling Kraft process has held on to its title in paper production because the chemicals it uses can be recycled within the plant itself. There are many better, less polluting ways to make paper, but they consume an impractical amount of chemicals which drives the price way out of economic usability.

This process will need to regenerate almost all of that sodium hydroxide and sodium sulfite, or it's just peracetic paper again.

[accrual]

I wonder if this can help offset the weakness of new growth wood - trees and wood specifically designed for fast growth and quick turn around.

https://brenthull.com/article/old-growth-wood

[hatsunearu]

https://www.youtube.com/watch?v=CglNRNrMFGM

Here's a NileRed video replicating the process.

[metalman]

There is a great deal of prior art in aviation and automotive engineering for densified wood, which have all proven to be non competitive with metal. Lighter, stronger, but not quickly adaptable to new designs or refinements.....the molds are large, complex, heavy, and expensive. And a simple no go for beams is that they(wood) burns and steel does not, will instantly remove them(wood) from bieng used in most building codes past a certain hight, where minimum times for evacuation durring a fire can not be met.

[IgorPartola]

So what size will a 2x4 be after that? 0.75x1.25 just doesn’t roll off the tongue, does it?

In seriousness, nominal vs actual sizing is just terrible. Do places outside of North America do this too?

[0x1ceb00da]

So I guess boiling and pressing will get rid of the trapped air inside wood and it won't work very well as an insulator?

[scythe]

Steel, itself, is a material with a wide range of properties. In terms of tensile strength, which is the simplest kind of strength to measure, steel ranges from mild steel at 400 N/mm^2 to piano wire alloys at about 2500 N/mm^2. "Stronger than steel" is a flashy appellation that usually means you have just reached the bottom end.

A similar phenomenon occurs sometimes in papers about ceramics research. A very tough ceramic will often see a comparison of its fracture toughness to that of aluminium; as you've guessed, this usually refers to the toughness of pure unalloyed aluminium.

[tapia]

If that is the case, then I don't see any novelty here. This has been done for a long time. In Germany, this is called "Panzerholz" (something like "bulletproof wood")

[nic547]

Modern Panzerholz (Kunstharzpressholz, 'synthetic resin densified wood') is manufactured with resin - this new material doesn't seem to rely on resin, but only on the cellulose contained in the wood.

[meindnoch]

Yes, but Panzerholz is plywood. They seem to be doing the same, but with bulk timber.

[brador]

Why isn’t panzerholz wood used everywhere? What is the article missing?

[mml]

"armor wood"

[kragen]

Liangbing Hu at UMD, checks out. Fantastic find! This should at least be the top comment on this thread to offset the content-free journalist pablum that's linked.

The strength is 483–587 MPa, I seem to see when skimming, which is indeed superior to ASTM A36 structural steel (250MPa yield strength). In Extended Data Figure 1c, they reported the density as 1.3g/cc, a sixth of the density of steel. (Extended data figure 2f plots density against lignin removal percentage.) Of course high-strength steels are stronger, but not six times stronger.

As for the process, they didn't just boil the wood; they boiled it with lye (2.5M, the "food industry chemical") and sodium sulfite (0.4M, technically also a food industry chemical, used for example as an antioxidant in wine) for 7 hours before densifying it with 5MPa for "about a day", removing optimally 45% of the lignin. This is similar to the sulfite chemical wood pulping process that preceded the Kraft paper process, just carried out at high pH and not taken to completion, so in a sense I guess the result is sort of like Masonite, which is also made from cellulose fibers from wood bonded with the wood's natural lignin.

Environmental concerns may be an obstacle; sulfite pulping is nasty. Also presumably to mass-produce the stuff they'll want to find ways to shorten the cycle time, and maybe already have.

The burning question that arises in my mind is why nobody was doing this in 01890, 135 years ago. Sulfite pulping was going gangbusters, building materials were booming, environmental concerns were largely unknown, and there was a rage for everything newfangled, modern, and "scientific". The scientific discipline of strength of materials, needed to calculate the benefits, was already well developed. Mason put Masonite into mass production in 01929, with a process involving autoclaving wood chips at 2800kPa. So what prevented someone from selling Superwood back then? Did nobody try partial alkaline sulfite pulping and pressing the result?

[dotancohen]

  > The burning question that arises in my mind is why nobody was doing this in 01890, 135 years ago

  > Mason put Masonite into mass production in 01929

Thank you for taking into consideration that for us readers, 1890 was 135 years ago. Just so you know, people from this era haven't started writing 4-digit years with the leading zero yet.

[neomantra]

Part of the strength is from Cellulose Nanocrystals (CNCs), which are modern (mid-01900's) and still being heavily researched. I was just at a conference where people were presenting work on making CNCs (and lots of other biomass conversion) more sustainable: H2O2 instead of SO4, greener versions of DMF like Cyrene, etc

My daughter recently started researching extracting/converting CNCs from fabric blends (currently cotton/elastane like spandex). Reading this post made me wonder if we can then remake fabric from CNCs, strong against knives or bullets?

[happosai]

Apparently it's not just me who thinks when someone says "food processing chemicals" that "hey, lye is food processing chemical too" - used to industrially peel mandarins. Weaselwording to make things sound benign.

[Maarten88]

> why nobody was doing this in 01890, 135 years ago

Maybe because at that time tropical hardwood was readily available at low cost?

[nine_k]

IIRC wood processed for strength was used in aviation until 1940s, so maybe somehow similar processes were known.

I suspect that the problem us, as usual, in the price. Also possibly with the high anisotropy of the material

[littlestymaar]

The antibacterial properties of penicillin had been discovered many times before it was eventually realized what a big deal it was in 1940 (Howard Florey's role is much more important than Flemings' for that reason).

So it's entirely possible that the process was found, and discarded straight away because they didn't realize how cool their invention was.

[permo-w]

why are you making the choice to place leading zeroes on your years?

[yubblegum]

> 01890 .. 01929

curious: What's with the funky date notation? Is this the new cool thing?

[zokier]

> This should at least be the top comment on this thread to offset the content-free journalist pablum that's linked.

The posted Techcrunch article directly links to the Nature paper, it is the very first link of the article

[cassepipe]

Total layman but I assumed that lignin was the molecule that was actually making the wood hard ? How does removing it improves hardness ? Why is there an optimal amount ?

As for the reason it wasn't my wild guess would be that they were already mining for coal so it may have been more economical to just dig the ground with quasi-slaves rather than having more competition on the wood resource and waiting for it to boil whereas you can just produce steel bar by the kilometer in a factory.

[sharpshadow]

There was a inventor in Germany which got featured in a science show on television, which did something similar. He build a big pressure cooker where he placed the wood and a liquid mixture inside and let it cook for many hours. The wood got soak through completely, which gave it, as he claimed, resistance against rotting at every layer. For outdoor appliances the wood would not need any coating and not deteriorate. There was no mention about the hardness, but he also didn’t press it.

[jefb]

Pressure treated wood is a very common outdoor building material.

[rajnathani]

InventWood's research paper mentions not just boiling, but boiling it with an "aqueous mixture of NaOH and Na2SO3", which also helps with "partial removal of lignin and hemicellulose".

[moffkalast]

That seems to really only provide benefits in use cases where weight isn't an issue, since this is conceptually just taking out air and adding more wood into the same amount of space to increase strength.

Correct me if I'm wrong, but almost all use cases for wood rely on it to be somewhat light, for which the lattice structure is already fairly ideal.

[kragen]

No, density is doubled, but strength is increased 11×, according to the paper. Sandwich panels with strong, stiff face sheets will always beat relatively homogeneous material like natural wood for the kinds of applications you are talking about.

[wolfi1]

in Finland they seem to have a similar method, where they bake the wood (they don't press it), the wood is then stable against rot and pests. please note: don't experiment with your oven at home, it will be unusable afterwards (because of the evaporating resins)

[jorts]

Heat treated wood is used in the US as well. I’ve seen heat treated ash used for exterior purposes.

[fho]

I would have thought that they remove the Lignin and replaced it with a (structurally better) resin.

[aitchnyu]

Can this make, say, planks out of sawdust?

[peatmoss]

MDF includes some binders, but is essentially this. Doubt the glue-free version would stick together well, but maybe.

The sawdust planks wouldn't have the properties of the long-grain wood fiber planks though. The fibers that make up natural wood are what makes the wood tough.

[accrual]

This is kind of how plywood is made - take wood chips and glue and press them together. I feel it wouldn't work well with sawdust, even with the chemical and heat+pressure process, since there would be little natural cohesion between the particles (larger pieces = more strength, up until you have entire logs/boards).

[Tagbert]

probably not. This does not work by adding a binder, like a plastic. This process softens the wood and then compresses it. I'm not sure that doing that with sawdust would give you enough tensile strength.