Primitive Archer
Main Discussion Area => Bows => Topic started by: upstatenybowyer on March 20, 2017, 07:59:25 pm
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So I was making dinner, staring out the window at the woods, and I started wondering... in ring-porous trees, what gives heartwood different physical characteristics that it's sapwood? I mean, wasn't the heartwood once sapwood? And if so, what process occurred that rendered the heartwood different than the sapwood? Thoughts?
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Yes, sapwood becomes heartwood over time. I believe the heartwood is denser.
Some woods (osage, black locust) do better with a heartwood back tough I've made bows of those woods with sapwood backs. Mostly because there was not enough heartwood for a bow.
With other woods (hickory, the oaks, maples, elms, etc) take off the bark and make a bow.
I don't know the why to all of this. I just know it works. :)
Jawge
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In TBB 1 Ron Hardcastle talkes about it for a little bit. Aparently the heart wood is where the tree sends all of its waste materials. These mineral/whatever deposits make the wood more dense and may somehow effect other properties.
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I hear ya Jawge. If something works I rarely ask why, but for some reason this topic was just giving me an itch.
gfugal, thanks man, that makes some sense. I guess those waste materials also account for the difference in color?
It gets me wondering about ERC too cause the purple heartwood "bleeds" into the creamy white sapwood with no regularity unlike osage where the difference is night and day.
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the sawood is new, and the heart wood is old,,,,????
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Does the heartwood do some kind of seasoning inside to become more dense?I've read that actually the heartwood is really not alive and that over time a trees' heartwood is nothing more that a big water canteen sealed in by the sapwood and cambium.
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This is a good start:
http://www.wood-database.com/wood-articles/what-is-wood/
Sapwood is still functional, holding and carrying moisture and nutrients (which is why bugs love eating it); heartwood is essentially dead, but contains "extractives" which can change its colour to darker and change some of its physical properties.
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Wood is dead. A skeleton for the tree. The only living part of a tree is the cambium and the buds. As the cambium lays down cells the sapwood is formed and as the sapwood matures it becomes heartwood in some trees. That's why the bark peels easily during the growing season. It is living but had no strong structure. In the fall the tree goes dormant and the cambium hardens off making the bark hold on.
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an excellent book for many such questions is.....
https://www. abebooks.com/servlet/SearchResults?sts=t&an=bruce+hoadley&tn=understanding+wood&kn=&isbn=
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Some of the main differences between the heart and sapwood is what PatB was getting at. The sapwood/xylem usually has more moisture in it than heartwood.mthe heartwood is kind of retired, it did its job and has been inaugurated in the heartwood club where it will stay. The heartwood is rich with sugars, oils and various minerals.
The sapwood often is not rot resistant and usually softer. I'm guessing that the rot resistance has to do with the heartwood being settled into its permanent state and the oils and such that are in it help prevent decay. Softwoods are non porous and hardwoods porous. Hackberry is ring porous, but it usually is hard to see much color change. I've wondered why Hackberry is good with a sapwood back and have not heard of anyone making a heartwood bow out of it. Which leads me to wonder if a heartwood hackberry bow would last longer? Hackberry can have really thick early wood rings sometimes and other times thin, I've noticed. I have processed two Hackberry trees recently and they are such opposites and they grew fifteen feet apart from each other. That kind of stuff interests me.
A fellow arborist was telling me the other day a tree that is completely rotten in the middle is by far safer to climb than a tree that has good heartwood and rotten sapwood. I've noticed this too while climbing/removing dead trees. It's been shown though the reason for this is not superior sapwood strength, but the cylinder shape that gives the tree strength. Like an empty coke can, very thin walls but it's the cylinder shape that gives its strength.
Often sapwood is more bendy, but it also has more moisture and is 'green'. I think about things like this a lot too upstate and when I'm working I am always testing and experimenting with trees. By the way Upsate I really enjoy your work, something for me to aspire to, take care.
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Heartwood is essentially infused with natural epoxy. If you pressure treat a softwood with epoxy you start seeing similar properties.
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Thanks so much Limbwalker. I love getting an arborists perspective. I've got a ton of respect for what you guys do. PatM, I was hoping you'd chime in. ;)
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Heartwood is essentially infused with natural epoxy. If you pressure treat a oftwood with epoxy you start seeing similar properties.
excellent way of formulating the difference.
Basically a tree (with clear heartwood demarcations) deposits in its dying sapwood various substances such as resins, gums, phenolic compounds (tannins), etc. Also, heartwood of many species has a higher relative lignin content, which gives it better compression properties. The process by which this lignin augmentation occurs, however, is poorly understood.
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Wow I learned me some stuffs