
Super Wood (2018) - bingden
https://www.scientificamerican.com/article/stronger-than-steel-able-to-stop-a-speeding-bullet-mdash-it-rsquo-s-super-wood/
======
Robotbeat
It would be appreciated if they used actual units and photos of the "super
wood."

"Stronger than (some low ball grade of) steel" is not a unit as it's super
easy to sandbag the thing you're comparing to and mislead people about how
important the development is.

Are units like MPa or psi not commonly understood by the science-curious
public? Why would someone like Scientific American not use actual units? This
stuff is taught to basically everyone in high school.

(Maybe this is just the graduate student instructor in me, but it bothers me
to no end that regular units are not used...)

EDIT: The paper does, of course use proper units (annoyingly, not in the
abstract...).

The densified "super wood" gets a specific strength (strength per unit
density) of: 422.2 ± 36.3 MPa/(grams/cm^3).

It is an impressive figure. State of the art carbon fiber is ~3900
MPa/(g/cm^3), though, and lots of other fibers are higher than this "super
wood" (including the best grades of Balsa, I believe).

Very thin gauge high performance steel ("piano wire") can exceed this slightly
(428MPa/(g/cc))

Good list:
[https://en.wikipedia.org/wiki/Specific_strength](https://en.wikipedia.org/wiki/Specific_strength)

~~~
salty_biscuits
Are units like MPa or psi not commonly understood by the science-curious
public?

Well no, nor is the term "strength". Is it yield strength, fracture toughness,
youngs modulus, etc, etc? Is that tensile, compression or shear you are
talking about? Carbon fibre is strong, but how about if you hit it with a
brick, then normal wood is "stronger". And then there is anisotropic
behavior... This stuff is complex.

------
Jun8
Link to _Nature_ paper
([http://nature.com/articles/doi:10.1038/nature25476](http://nature.com/articles/doi:10.1038/nature25476))
with some nice photos.

This could be an interesting Science Fair experiment:

1\. Get the following from Amazon (or your favorite online store) NaoH, $14
([https://www.amazon.com/FDC-99-Pure-Sodium-
Hydroxide/dp/B013K...](https://www.amazon.com/FDC-99-Pure-Sodium-
Hydroxide/dp/B013KMNCJU)). Also get Na2SO3, $16
([https://www.amazon.com/Sodium-Sulfite-Na2SO3-Powder-Space-
Sa...](https://www.amazon.com/Sodium-Sulfite-Na2SO3-Powder-Space-
Saver/dp/B00WSJT19C)) and deionized water, $24
([https://www.amazon.com/Deionized-Water-Gallon-ASTM-
Type/dp/B...](https://www.amazon.com/Deionized-Water-Gallon-ASTM-
Type/dp/B07QDBSQVS))

2\. Get an oak block (See paper for other types of woods that can be used)
from Home Depot, $14 ([https://www.homedepot.com/p/Builders-
Choice-1-in-x-2-in-x-8-...](https://www.homedepot.com/p/Builders-
Choice-1-in-x-2-in-x-8-ft-S4S-Red-Oak-Board-O-BD10208X/206201578))

3\. Place 2.5M NaOH and 0.4M Na2SO3 in a pot, boil. Place small block of oak
in it. Boil for 7 hours. Of course, should do this outdoors or in a hood.

4\. In a separate container bring ionized water to boil, immerse piece of wood
several times in it.

5\. Press wood block perpendicular to the wood growth direction at 100 °C
under a pressure of about 5 MPa (~50x atmospheric pressure) for about 1 day

6\. You have your super wood to test

Step 3 is possible for hard-core science fans to do at home, Step 5 is
problematic for that scenario.

~~~
pacaro
You could probably make a bottle jack press for step 5, this is probably the
most obvious limiting step for size without access to industrial equipment
though

------
ethagknight
Link to actual paper, much more interesting than the article, lots of
pictures!
[https://www.fpl.fs.fed.us/documnts/pdf2018/fpl_2018_song001....](https://www.fpl.fs.fed.us/documnts/pdf2018/fpl_2018_song001.pdf#page1)

Prior discussion on HN:
[https://news.ycombinator.com/item?id=16331375](https://news.ycombinator.com/item?id=16331375)

------
scythe
> _Perhaps most importantly, the densified wood is also moisture-resistant: In
> lab tests, compressed samples exposed to extreme humidity for more than five
> days swelled less than 10 percent—and in subsequent tests, Hu says, a simple
> coat of paint eliminated that swelling entirely._

This is an improvement, but it doesn’t appear to solve the fundamental
problem: rain. In practice most structural materials must survive exposure to
not just humid air but liquid water — this is why Sorel cement is not used in
construction, for example.

~~~
hinkley
Rain and standing water caused by rain.

Wicking can be a bitch, and some wood products do not bounce back. Wet a 2x4
and as long as you dry it before rot sets in, good as new. Fiber board, at the
other end of the spectrum, ruined forever. There are a lot of things in
between.

So they said paint prevents swelling but they don't say what happens to the
swelled wood after it dries.

------
omegaworks
This is a great followup to the steel issue raised by Gates discussed earlier
here.
[https://news.ycombinator.com/item?id=20813496](https://news.ycombinator.com/item?id=20813496)

It seems like the carbon cost for creating this stuff might be much less.

------
newsreview1
"The material does not protect quite as well as a Kevlar sheet of the same
thickness—but it only costs about 5 percent as much" \- Incredible. Millions
could be saved to protect the military and police. Additionally it could
provide less weighty armor and improve performance. There has been a lot of
talk about the weight of full military body armor, and I wonder how much this
new material would weigh, and if comparable to kevlar but lighter, could
improve performance. [https://www.military.com/daily-news/2018/09/25/army-
body-arm...](https://www.military.com/daily-news/2018/09/25/army-body-armor-
may-be-too-heavy-combat-report-finds.html)

~~~
aidenn0
It's almost certainly heavier than the kevlar equivalent. It might be a good
material for quickly building fixed fortifications though, or more cheaply
armoring vehicles.

------
rectangletangle
I wish this article had some photos, particularly of the transparent wood.

~~~
hsnewman
[https://www.google.com/search?q=transparent+wood&rlz=1C1GCEA...](https://www.google.com/search?q=transparent+wood&rlz=1C1GCEA_enUS864US864&oq=transparent+wood&aqs=chrome..69i57&sourceid=chrome&ie=UTF-8)

------
Koshkin
There is also the so-called "delta wood" (resin-wood multi-ply veneer) that
was used in some of the WW2 fighters' airframes.

~~~
noir_lord
The Mosquito also known as 'The Wooden Wonder' \- fastest thing in the sky til
the Germans got the Me-262 off the ground.

Didn't do well in the far East because of humidity but they cracked that
later.

Brilliant bit of engineering since it used a lot of equipment/skills that
where under utilised at the time they started building them.

With the F18 and the Lightning one of my top 3 favourite military planes ever.

