Going to Woodworking School #4: Wood Technology: Day Two part one

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Blog entry by John Fleming posted 10-30-2009 11:59 PM 11204 reads 0 times favorited 3 comments Add to Favorites Watch
« Part 3: Safety and more Safety Part 4 of Going to Woodworking School series Part 5: Day Two Con't »

Topics covered in this section listed below:

Terminology Wood science
Hardwoods and Softwoods
Seasoning and Drying
Warps and Defects
Board Footage
Urban Lumber

Parts of a tree:

Parts of a Tree
Sapwood is the new wood as newer rings of sapwood are laid down its inner Cell lose their vitality and turn to heartwood. Heartwood is the essential supporting pillar of the tree. Although dead it will not decay or lose strength while the outer layers are intact.

The Outer bark is the tree’s protection from the outside world. It keeps the moisture out during rain, prevents the loss of moisture when the air is dry, insulates against cold and heat, and wards off insects. the inner bark or “Phloem” is the pipeline through which the food is passed to the rest of the tree. It lives only for a short time then dies and turns to cork, to become part of the outer protective bark. The Cambium Cell layer is the growing part of the truck. It annually produces new bark and wood in response to hormones that pass down through the phieom with the food from the leaves. Sapwood is the tree’s pipeline for the water moving up to the leaves.

Courtesy of St. Regis Paper Company
Wood Science: tree cells

Wood cells;

Wood Cells

The structural elements of wood tissue are of various sizes and shapes and are quite firmly cemented together. Dry wood cells may be empty or partly filled with deposits, such s gums and resins or with tyloses. The Majority of wood cells are considerably elongated and pointed at the ends; these cells are customarily call fibers or trachieds. The length for wood fibers is a highly variable within a tree and among species. Hardwood fibers average about 1 mm (w/25 in.) in length, softwood fibers range from 3 to 8 mm (1/8 to 1/3 in.) in length.

In addition to fibers, hardwoods have cells of relatively large diameter known as vessels or pores. These cells form the main conduits in the movement of sap. Softwoods do not contain vessels for conducting sap longitudinally in the tree; this function is performed by the trachieds.
Both hardwoods and softwoods have cells (usually grouped into structures or tissues) that are oriented horizontally in the direction from pith toward bark. these groups of cells conduct sap radially across the grain and are called rays or wood rays. The rays are most easily seen on edge grained or quarter sawn surfaces and they vary greatly in size in different species. in oaks and sycamores the rays are conspicuous and add to the decorative features of the Wood. Rays also represent the planes of weakness along which seasoning checks readily develop. Another type of wood cells known as longitudinal or axial parenchyma cells, function mainly in the storage of food.

Day One continued next blog posting

-- Woodworker in Progress, Oceanside CA

3 comments so far

View TraumaJacques's profile


433 posts in 2923 days

#1 posted 10-31-2009 03:08 AM

Man! I went to nursing school and the human body did not look that complicated. But nice to know.

-- All bleeding will eventually stop.

View stefang's profile


15512 posts in 2756 days

#2 posted 10-31-2009 06:57 PM

Tree anatomy is very interesting and I think you have done a great job giving us an appropriate amount of detail for us who don’t know much about trees or wood.

The thing that irritates me most is that in spite of my almost 70 years I still find it difficult to identify a tree from its visible characteristics (of course I do recognize some trees). This is partly due to only being really interested in trees I can make something out of, but in fact most trees are useful for woodworking projects. I’m not exceptionally bright, but I guess I could learn it as well as most others if I focused on it a little. I guess my excuse is being just plain lazy. Not a commendable trait. It would be nice if someone would do a blog or a series of blogs on tree identification. Since you are interested in tree anatomy maybe you are interested in tree identification too? Just an idea. Lazy people like to get others to do all the hard work. Oops, there I go again!

-- Mike, an American living in Norway.

View MsDebbieP's profile


18615 posts in 3583 days

#3 posted 11-02-2009 09:49 PM

I didn’t go to nursing school but I like TraumaJacques interpretation.


-- ~ Debbie, Canada (

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