Notes on wood care, use, and drying.

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Chris Hall
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Re: Notes on wood care, use, and drying.

Sat Mar 11, 2017 6:36 pm

Daruma wrote:I am still curious why sap in Maple trees only moves in above freezing temperatures.
So do scientists it seems. Quoting Gene Wengert again:
It is my understanding that turgor pressure refers to the minute action within a cell, but does not account for sap flow itself in a tall tree, especially in a species like sugar maple in the early spring before leaf growth starts. In fact, we need to recognize that virtually all cells in the stem of a tree are dead. Further, the cells of a tree are filled with about half water and half gas... If they were all water, trees or logs would not float, as wood itself is 1.5 times heavier than water. Unfortunately, the literature is full of theories on sap flow that are incorrect when applied to tall trees, but do work for short plants.
In a tree, does water flow up in the sapwood and down in the bark? Or is it the other way? In other words, how do the sugars of photosynthesis get down the tree? Another comment is that wood cells, when first formed in the cambium layers (which was once thought to be a single layer of cells) are full size and do not grow longer or fatter. In fact, soon after creation, most of the cells die... Maybe some ray parenchyma cells remain active.

Joyce Kilmer may have said it best:
I think that I shall never see
A poem lovely as a tree.
A tree whose hungry mouth is prest
Against the earth's sweet flowing breast;
A tree that looks at God all day,
And lifts her leafy arms to pray;
A tree that may in summer wear
A nest of robins in her hair;
Upon whose bosom snow has lain;
Who intimately lives with rain.
Poems are made by fools like me,
But only God can make a tree.
I think every woodworker should have a moisture meter. It's an essential tool.
Matt J
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Re: Notes on wood care, use, and drying.

Sat Mar 11, 2017 7:03 pm

Thanks Chris,

I do get a kick out of hokey religions and ancient weapons, but at the end of the day I want a good blaster at my side.
though there remain unsolved mysteries -
This reminded me of The Hidden Life of Trees: What They Feel, How They Communicate—Discoveries from a Secret World by Peter Wohlleben,
which I'm sure many here have read. For those who haven't I highly recommend it!
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Chris Hall
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Re: Notes on wood care, use, and drying.

Sat Mar 11, 2017 8:01 pm

I wonder if after years back in America where time equals money he realized people just won`t pay the cost of air drying
I doubt it - in regards to cost alone. Japanese architecture here is priced at the thin end of the wedge, so to speak, and a variance in the cost of air drying vs kiln drying is, to my mind at least, a minor factor in overall price. Rather more a factor is time pressure to get projects done within people's normal expectations in a world where buildings go up in a hurry for the most part. A lot of people want it 'now', and they are used to contractors delivering on that.

With the MFA gate, I needed a full 10 months just to adequately dry the main posts and crossbeam, and just barely delivered the project on the timetable the museum wanted.

Hence, on new architectural projects, an important discussion to have with the client is the issue of quality wood procurement and drying, and see how that works with what their expectations might be. If one were faced with losing a job or kiln-drying material, well, which way to go?

Also, if you produce a product and have a problem with it later due to the moisture content of the material being above equilibrium value to the environment in which the piece resides, then the business cost of addressing that, and the mark it can make on your reputation, makes one think very carefully about the issue of moisture content in future projects.
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Chris Hall
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Re: Notes on wood care, use, and drying.

Sat Mar 11, 2017 8:34 pm

Matt J wrote:Thanks Chris,

I do get a kick out of hokey religions and ancient weapons, but at the end of the day I want a good blaster at my side.
though there remain unsolved mysteries -
This reminded me of The Hidden Life of Trees: What They Feel, How They Communicate—Discoveries from a Secret World by Peter Wohlleben,
which I'm sure many here have read. For those who haven't I highly recommend it!

I've thumbed through that book but not read it in detail. I'll give it a closer look following your recommendation.
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Chris Hall
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Re: Notes on wood care, use, and drying.

Tue Apr 04, 2017 10:17 am

You will obtain the most accurate reading by taking the measurement in the center of the face of the board, with pins that reach at least 40% to the center of the board. The pins should line up with the longitudinal axis of the wood—in other words, with the grain, not against the grain. For thicker boards, and with harder woods, you will need to drill holes and insert nails to use as probes to the correct depth.

You will obtain the LEAST accurate readings by taking the measurement from the end grain at the end of a board, or very close to the end of the board. Wood dries from the outside in, and due to cellular structure it will lose or gain moisture very rapidly through the end grain. On the edge of a board, it is also losing moisture fairly rapidly, so that is also a less than ideal place to measure. Remember that the end grain of wood dries up to 50 times faster than the edge or the face. The ends, therefore, dry rapidly and shrink, while the center of the panel dries and shrinks more slowly.

An article:

http://www.thisiscarpentry.com/2011/09/ ... re-meters/

Note the "Using Moisture Meters" section in particular.
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Chris Hall
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Re: Notes on wood care, use, and drying.

Tue Apr 04, 2017 4:22 pm

Often the pin holes can be sawn around or hidden by orientation in the piece, or patched easily enough. It is a definite negative to the pin type meters though...
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Re: Notes on wood care, use, and drying.

Sun Apr 30, 2017 5:41 pm

Daruma, my moisture meter (also pin type) comes with a species correction table. Are the examples you showed corrected for species?

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