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Author Topic: Hardness of Lumber  (Read 1138 times)

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Offline newoodguy78

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Hardness of Lumber
« on: September 02, 2016, 10:06:43 pm »
Hopefully this is in the right section. I've been reading the Magicman post about the loss of his champion Oak, very impressive tree for sure. The age stated for the tree is 150 years. In the northeast where I hang my hat that tree would be much older I would guess simply because of slower growth rates. That leads to my question. Would two trees of the same species have the same hardness on the janka? scale, if one grew in the north and one grew in the Deep South. Also does the fast growth effect the quality?
I'm not questioning the age of the tree in any way it simply got me thinking.
Thanks in advance for any replies.

Offline Okrafarmer

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Re: Hardness of Lumber
« Reply #1 on: September 02, 2016, 10:12:07 pm »
Wow, those are great questions! Some of the more educated people on here can give you scientific answers, but I'm pretty sure the short answer is, yes, there is some measurable difference in overall hardness, and quality, depending on the size of the growth rings. This is because the early wood and the late wood in each year's growth ring do not maintain the same proportion to each other when comparing a narrow growth ring to a wide one, and the early and late growth wood have different strength characteristics. They definitely behave differently, both in load-bearing as well as in warp resistance.

Now to see if one of the really scientific people can chime in to explain it better.
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Offline WDH

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Re: Hardness of Lumber
« Reply #2 on: September 03, 2016, 07:51:24 am »
Not sure about "hardness".  As to density, in ring porous hardwoods like oak, faster growth means denser, heavier wood.  I know that sounds counter-intuitive.  In slow growing ring porous hardwoods, there is proportionally more of the large earlywood pores that the tree puts down in the Spring to jump start the movement of water to the crown and get photosynthesis up and running, versus the smaller pored, denser latewood that the tree puts down after that initial, early growth spurt.  The fast growing trees put down proportionally more denser latewood versus earlywood, especially when the growing season is longer, like in the South. 

But, what is "quality".  The slower growing Northern red oak, for example, has a more pleasing grain pattern that the fast growing, Southern red oaks, in my opinion, and more heartwood.  The density difference does not mean all that much in red oak, so "quality" can be more visual and "in the eye of the beholder". 
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Offline newoodguy78

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Re: Hardness of Lumber
« Reply #3 on: September 03, 2016, 10:08:38 pm »
WDH thanks for the info. It's surprising to me that the northern trees are less dense, but that's why I had to ask.

As far as the "quality" I was referring to stability upon milling,drying and the overall workability and "eye appeal" of the wood.
I've only dealt with northern hardwoods hopefully someday I'll get my hands on some hardwood to try from other parts of the country.

I hope I didn't come across as sounding like one region is better than the other. Thanks again

Offline Okrafarmer

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Re: Hardness of Lumber
« Reply #4 on: September 04, 2016, 12:11:01 am »
eye appeal is in the eye of the beholder, and I prefer the looks of narrow-ring wood. However, I've been told (and it makes sense) that faster growing (wider-ring) wood is stronger. However, it does seem that wide growth rings in some cases can tend toward wood that warps more easily. Sometimes when planted in lawns that get fertilized and watered regularly, some hardwoods (and softwoods) can have phenomenal annual growth around here and farther south. Sometimes water oaks and yellow poplars in this area can put on an inch or more per year of diameter under the right conditions.
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Offline Ianab

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Re: Hardness of Lumber
« Reply #5 on: September 04, 2016, 02:23:10 am »
There are various issues with fast growing trees.

But it's mostly to to do with "juvenile" and sap wood, which behaves differently. So if you have a tree with ~1" growth rings, the first 5 are probably "juvenile" wood, which can shrink more in length. The other 5 rings are sapwood, that can also be unstable. So you have a nice looking 20" log, that produces pretzel wood, because the tree is only 10 years old, and hardly more than a sapling.

Where a slow growing tree might reach 20" in 50-100 years, and only that center 1" is juvenile, and the outside 1" is sap wood. Means lots of good stable wood in the middle.

But it depends a lot on species. A lot of tropical woods have that high growth rates, and a tree is "old" at ~60 years. But they produce hard and stable timber.
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Offline longtime lurker

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Re: Hardness of Lumber
« Reply #6 on: September 04, 2016, 03:52:11 am »
This is one of the issues that is beginning to face the hardwood industry here.

There is a strength difference between plantation sourced material and forest sourced material that is attributable to the age of the tree at harvest, plus location etc etc.  Thing being that it is difficult to tell what came from where when you're assigning a structural grade. Because of the way the visual grading system we use works what they're beginning to talk about is reducing the maximum strength grade that some species can gain because of the chance that its plantation material.

Theres not a lot of machine proof grading in the hardwood industry here, but based on some samples that we supplied to a trial a few years back "my" old growth tropical timber was grading two strength grades higher then the same species sourced from a plantation in a temperate area by machine testing, but visually it all had to be lumped together.
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Offline Okrafarmer

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Re: Hardness of Lumber
« Reply #7 on: September 04, 2016, 09:06:44 am »
Ianab, that's probably why cherry is so difficult to deal with in my area. Not enough heartwood percentage compared to juvenile and sapwood. Could also go a long way toward explaining sweetgum's problems-- heartwood is often octopus shaped, to put it kindly. Octopus shaped, surrounded by a school of minnows.

But I have found that large diameter sweetgum logs (over 18") tend to be much more stable to dry than the smaller ones.
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Online Magicman

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Re: Hardness of Lumber
« Reply #8 on: September 04, 2016, 07:43:06 pm »
This is a good question and certainly "food for thought", newoodguy78.  It's nice to see my old (now dead) Champion Tree still living in a sense and provoking questions.  I had never considered growth rate vs hardness.   :P

I have no idea as to the actual age of that old tree or whether it was fast or slow growing.  My only gauge is that I am 73 years old and I have no memory of it ever being anything except big.  When it was measured in 2010 at 233" the next larger tree was less than that.  That tree now measures 242" six years later, so my new Champion Tree is certainly still growing.  It has grown ~4" in diameter in 6 years.  I also need to measure tree #3 and check it's growth rate. 







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Offline Okrafarmer

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Re: Hardness of Lumber
« Reply #9 on: September 04, 2016, 09:55:39 pm »
Your new champion is 6'4" DBH! Wow!  :o  :o  :o  :o  :o  :o  :o  :o  :o  :o  :o  :o

And to be adding 1/3 inch growth rings each year (2/3 inch diameter growth), it's really still kicking!
No matter how conventional wisdom may fly in the face of radical thought, it's still the most popular type.

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Offline newoodguy78

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Re: Hardness of Lumber
« Reply #10 on: September 05, 2016, 09:37:50 pm »
This is a good question and certainly "food for thought", newoodguy78.  It's nice to see my old (now dead) Champion Tree still living in a sense and provoking questions.  I had never considered growth rate vs hardness.   :P

I have no idea as to the actual age of that old tree or whether it was fast or slow growing.  My only gauge is that I am 73 years old and I have no memory of it ever being anything except big.  When it was measured in 2010 at 233" the next larger tree was less than that.  That tree now measures 242" six years later, so my new Champion Tree is certainly still growing.  It has grown ~4" in diameter in 6 years.  I also need to measure tree #3 and check it's growth rate.
[/quote

I think sometimes not knowing the exact age of trees adds to the mystique and allure. I've never been in your area much but it's great to think about how the changes and occurrences that tree has "seen" . Glad to hear you have a healthy one already taking its place