Why Is Wood So... Woody?

Wood is truly an amazing substance. Relatively light, very strong for its weight, elastic, capable of being shaped to an extraordinary degree. Why is wood so... woody?

Wood Handbook, FPL-GTR-113: Forest Products Laboratory. 1999. Wood handbook--Wood as an engineering material. Gen. Tech. Rep. FPL-GTR-113. Madison, WI: U.S. Department of Agriculture, Forest Service, Forest Products Laboratory. 463 p.

It seems clear that competition between plants has a bunch to do with it: whatever plants can get their leaves higher and wider spread has a big advantage in photosynthesis and thus in fitness. It seems pretty clear that wind has a bunch to do with it: wind can put great stresses on plants--especially those that reach high and are widely spread.

But I really do wish that by now somebody had told me why wood is so... woody.

Tomorrow: I also wish someone would tell me why doping iron with carbon atoms changes its properties so much...

Comments

[VKW]

Not exactly up to date, but I enjnoyed J.E. Gordon's "The new science of strong materials or Why you don't fall through the floor" (second edition 1976). Very readable, and the man loves wood!

[DCA]

Second the motion: it is a very readable introduction to fracture machanics (why things do and do not break), with lots of good stories--and he does talk about iron and steel. Hint--it's all about cracks and how to stop them.

[A. Zarkov]

I highly recommend “Understanding Wood” by Hoadley

http://www.amazon.com/exec/obidos/tg/detail/-/1561583588/qid=1114917904/sr=1-1/ref=sr_1_1/104-3961694-2533519?v=glance&s=books

Although aimed at the wood worker it has a great deal about wood technology and very good graphics and pictures. I like the discussion of the different cuts. The oak doors you see nowadays with that “grainy look” are actually from made the inferior cut. The doors on fine old fine houses use quarter-sawn oak—far more elegant.

And fracture mechanics, another application of extreme value theory. Once again statistics has a lot to say about how the world works.

[shah8]

eeek, and I thought *I'd* be the first materials guy to show up!

and yes, there's alot of fun to be had in materials science ?;~)

[JR]

Redwoods are the SUVs of the natural world.

[Leszek Pawlowicz]

Why does carbon in iron have such a huge effect? Try these links:

Austenite: http://www.physicsdaily.com/physics/Austenite

Martensite:
http://www.physicsdaily.com/physics/Martensite

Steel:
http://www.physicsdaily.com/physics/Steel

[derek]

Damn, scooped by everyone else! J. E. Gordon's books The New Science of strong Materials, or Why You Don't Fall Through The Floor and Structures, or, Why Things don't Fall Down, were the reason I eventually went off to do a materials science degree.

Oh well, I suppose it was such an obvious response; you could almost have been leading us to recommend Gordon, with that particular choice of questions.

[derek]

You know your comment system sucks? Those long book titles were meant to be set off in italics. Let's try this again: that's _*The New Science of Strong Materials, or Why You Don't Fall Through The Floor*_ and _*Structures, or, Why Things don't Fall Down*_.

[Kevin Donoghue]

Somewhere in the above-mentioned books you will find the lines:

Plastics are made by fools like me
But only God can make a tree.

[Unstable Isotope]

Next materials science questions: why is glass so glassy and why is rubber so rubbery?

[obscure]

Speaking as a carpenter I wood have to say,

"Beats heck outta me... but it sure does cut, glue, nail & screw purty well."

Also, it's a hydraulic system built from Water, Sunlight & Sugar. What's not to like?

[Barry Freed]

"Why is Wood So... Woody?

Funny that, I woke up this morning asking myself the same exact thing.

[shah8]

about glass and rubber...

Defect travel. Like all ceramics like stuff, glass only has a very few paths for a defect to travel, and they quickly get knotted up, more quickly than metal would, for example...

Rubber has polymers and their properties are affected by how long the polymer string is and basic properties of the polymers, any sulfide bridges, any number/type of side groups, lots of hydrogen, etc, etc. Jeez, but I forget alot of stuff for rubbers though, those are really complicated. We have to judge by how *crystalline* any polymer solid is, to compare with other materials like metals or ceramics. Rubber can behave like a glass too, when it is very cold. Such things like rubber has solid stage, glass transition temp, rubber transition temp and all that lovely stuff.

[Cranky Observer]

> Next materials science questions: why is
> glass so glassy

That, in fact, turns out to be an exceedingly complex question, as even a quick perusal of the above mentioned /New Science of Strong Materials/ and Richard Feynmen's introduction to quantum physics for laymen will make clear (ha ha).

Triple the vote for both /New Science/ and /Structures/ - great books.

Cranky

[Michael Cain]

Brad: "It seems clear that competition between plants has a bunch to do with it: whatever plants can get their leaves higher and wider spread has a big advantage in photosynthesis and thus in fitness."

Having grown up on the Great Plains, I was always fascinated that grass won there in large part by adopting fire as a tool. A prairie fire burns off the built-up thatch, putting trace nutrients back into the soil, and kills off any saplings that have gotten started. Since a typical stretch of native prairie got burned over every five years or so, trees couldn't get established. Except along the rivers and streams, where it was too damp for a good grass fire.

Why doesn't Brad allow italic or bold tags in comments? Does he fear empowering his readers? Just kidding...

[media in trouble]

xylem and phloem baby
its all about the x and p

aka fiber

otherwise perhaps you should ask a termite

[dilbert dogbert]

Next question. Why does fracture mechanics predict small critical defect sizes in low carbon steels when the actual ciritical defect size is very large?
Or has this problem been solved. My last experiece with this was in 1986 when we found a 114 inch long crack in a pressure vessel that had operated for 40 years at pressures varying from vacuum to 75 psig. Fracture mechanics at that time predicted an 18 in long crack would lead to explosive failure.
The lession from this is don't hydrotest pressure vessels and and belive that the vessel is safe to operate if a crack does not open.

[John Emerson]

Bamboo is more amazing than wood.

"The Coming of the Age of Iron" by Theodore A. Wertime and James D. Mulhy has tons of stuff about the history of iron and steel production back to the beginning, though only a little bit about the physics of iron and steel. Up until recently people thought steel was purified iron, but actual it's contaminated with copper.

[Egg]

Brad:

"It seems clear that competition between plants has a bunch to do with it: whatever plants can get their leaves higher and wider spread has a big advantage in photosynthesis and thus in fitness."

. . . and cooperation, and context. It's all about occupying a niche in the local environment that allows a plant (or animal) to be fit or successful enough to pass on its genes. If a big tree becomes so 'succesful' in its niche that it crowds out the necessary sun for the plants on the forest floor (which used to grow, die and decay and provide nutrients for the big tree) to continue, then that 'successful' tree goes extinct in that area and you've never heard about it.

You can also take that great, dense pine tree growing in Northern California that makes wonderful construction lumber after it's grown to 100 feet high in 70 years; transplant it to Maui to take advantage of tropical rains and year round sun in order to get it to 100 feet high in 35 years and find that the wood is soft, pulpy and not suitable for any commercial purpose. But the tree may still be "fit" and "successful" enough in its new context to allow it to continue to pass on its genes.

Fitness or success relative to usefulness to man is a very specific and narrow context in biology (or geology or chemistry or . . .). So, whenever you're asking questions about how the world works -- how it "works" and how it "works for" the benefit of specific men at a specific point in time are completely different questions. But, then you are an economist. . .

Sorry to complicate a simple fun question -- recently, I can't help it.

[Josh Narins]

What is a tree is a fun question.

A tree is a solar powered machine for turning air into wood.

The carbon of the woodiness of wood comes from C02.

[Josh Narins]

Some Annenberg/CPB biology video series had that quote. "solar power-machine for turning..."

[Karlsfini]

Some years ago a boatbuilder showed me an original copy of the Wood Handbook. It was from the late 1930's, I think. He said it was out-of-print and I took his word for it.

I kept thinking I'd try to track down a copy someday. Now I don't have to.

Thanks, Brad

[dca]

To tie together two topics on this blog: another example of different tree responses to different climates comes from the pine, Pinus Radiata. When visiting New Zealand I was told by friends that they had planted several acres with this because, after 25 years, they could harvest it to help cover their retirement (so, the tie to Social Security). They also said the tree was a California native--but I had never heard of it. Turns out this is Moneterey pine, which in Monterey looks like giant bonsai, not useful at all, but in NZ grows fast, straight, and tall. Not the world's best lumber, but fine for shipping crates and such.

[MonkeyBoy]

Wind actually makes wood strong. I've heard that indoor dope growers have to use fans to ruffle their plants. Without wind the stalks are weak and often collapse.

[JimPortlandOR]

"Why doesn't Brad allow italic or bold tags in comments? Does he fear empowering his readers? Just kidding..."

I'd get woody about italics and bold being permitted here.

Why Oh Why does Brad hate commenters and fear their self-expression?

Oh, and why do slugs prefer Begonias above all other plants?

[John Emerson]

"What is a tree is a fun question.
A tree is a solar powered machine for turning air into wood.
The carbon of the woodiness of wood comes from C02."

Another fun thing is to compare the leaf structure of trees to the structure of gills (especially external gills of creatures like nudibranches) and of lungs. I imagine there's a technical treatment of it but just looking at pictures and diagrams a similiarity is noticed.

[Dubblblind]

Egg started down the path I was headed. New growth "managed" trees grown in artificial circumstances grow faster but are decidedly inferior. The coming question will be "why is wood so...less woody".

[Karsten M. Self]

Q: What's brown and sticky?

A: A stick.

Yes, wood (and other natural materials) are pretty amazing. I was ruminating over properties just a couple of days ago -- chanced by a bit of ply on the side of a road while biking, thinking about the properties of plywood, straight lumber, pressboard, and other wood-derived materials. It's a bit odd noting the things that will keep your mind occupied at times....

Nice diversion, Brad.

[Big Al]

Glass is "Glassy", because it is a supercooled liquid. Have you seen desert glass where the sodium ions have been moved by the radiation and the glass has changed color? And finally an excavation in London, came across a Roman Glassworks with a large pile of cullet.

[jm]

"Why Things Break" by Mark Eberhart discusses not only the materials science, but also defects in our current system for supporting scientific research. I strongly recommend it.

[Hedley Lamarr]

Squirrels rely 100% on wood products.

[Keith M Ellis]

"Glass is 'glassy', because it is a supercooled liquid."

According to some definitions of "liquid" and not others. The materials scientists above (almost certainly) do not think of glass as a liquid (they would classify it as an "amorphuous solid"). Phycisists do, on the other hand, tend to consider glasa a "supercooled liquid". But then, they consider quite a few other things "liquids" that no one else ever would. For ordinary purposes and regarding real-world properties of glass, the materials scientist view of glass as is much more correct and avoids the extremely unfortunate implications of the term "liquid" that lead to popular fallacies about the behavior of glass—for example, the myth that old glass sags downward in windowpains due to gravity. That myth, and the general idea that in any practical sense glass "flows" like a liquid is authoritatively, undoubtedly false. (And it is. Please don't argue about it here; do an extensive Google search to verify my assertion.) On the other hand, the definition of "liquid" and "solid" and, well "glass" is not so much a matter of empirical fact as it is nomenclature and that nomenclature varies from discipline to discipline.

[Saam Barrager]

RE: Competition with other plants...

Wood that works best for exterior uses is that which has had to contend with tropical pests. Southeast Asian hardwoods (like Teak or Kembra) or Brazilian (Ipe or Cambara) are durable, retain their color, and are pest resistant - even with little or no treatment. Redwood seems to be the best choice among North American woods - but even so needs much treatment.

Wood also expands and contract, which gives it properties that are both desirable and undesirable given the context. Water absoption bad! Conform to minor seismic shifting good! A table in a controled environment is a perfect use for wood - outside that same table needs gobs of chemicals to make it work. Fencing and decking both require clever water management.

For these reasons wood can't really be seen as better or worse than other building materials, just that it has properties that require special handling.

[P.M.Lawrence]

Down at the molecular level, wood is made of the natural versions of higher sugars like cellulose and lignin. These end up with different crystalline behaviour along their length in such a way that they do block copolymer-like stuff. That allows a great deal of fine tuning, unlike what you get if you reconstitute cellulose to make rayon. Google for the stuff on synthetic rubbers like ABS to see the sort of fine tuning man can do in this area.

On doping iron with carbon, the short answer is that it doesn't make that much difference on its own - the main difference comes from all the other things that it opens the door to, that get done as well. It all adds up, but the original "science" was so unpredictable that metallurgy is an "-urgy" and not an "-onomy" let alone an "-ology".

[agm]

ARRRGH. Never, ever come here straight after reading Bitch. PhD. Also, thanks for the titles, sound fun.

And, Keith Ellis, glasses do indeed flow, all solids do to some extent, it's just that the timescale for this to be noticable this may be, oh, on the order of the age of the universe. Why yes, I am in physics, why do you ask? =)

[PHG]

RE: Competition with other plants ...

Can you prove that wood isn't woody because of intellegent design? I DEMAND equal comments refering to wood being woody because God (and remember that's MY God not your god) made it woody.

[The Bobs]

Trees are pre-stressed structures. The outer portion in in tension and the inner part in in compression. This makes a tree much more resistant to bending than it would be otherwise. It's also why wood warps.

[Randolph Fritz]

Light, gravity, air, water, and carbon, making use of energy at the bottom of the sky.

[Dano]

This is why I read this blog. I have a forestry degree and came late to this post. Scanning down the comments, I see that I have nothing of substance to add, and see lots of stuff that I did not know.

Thanks Brad.

D

[calmo]

Not one connection to music. All those stringed instruments and some of the woodwinds beg for your attention to their lovely bodies that accounts for those lovely tones.

[ogmb]

These are of course all preliminary answers, and for the final answers we have to wait until the Fafblog Science Team weighs in.

[Erick]

Wood is so woody bacause it's made of wood!!!!

[California Refinance]

An improved knowledge of wood material behavior in hot-pressing environments can provide the benefit of an increased understanding of material properties during the manufacture of wood-based composites as well as insight into the development of new processes and products which manipulate the viscoelastic nature of wood.

[hairstyles]

I like wood. It gives more energy than metal.