[canadiancarver]

hi there ive read in some forums people talking about heartwood? where is this part of the tree found? and why is it better then the rest of the tree? thank you

[AlArchie]

If you were to cut a section out of a tree and look at it like a circle, the heartwood would be the central core area. I don't think it is always any better than the rest of the tree and quite often it is the first to rot away, being the farthest from the actual live cambrium layers out near the bark. Check out some log trucks and you will see a LOT of hollow logs going to market.

Quite often it is a darker color than the outer layers and adds contrast to the boards cut from the tree. There may aslo be some very impressive grain figure in these core areas, especially if you manage to get a cut from a crotch area, where several limbs join. the heartwood here is bifurcated and may vary in width and color as it blends into each limb.

In some trees, this center is called "pith" and is quite soft and punky. The sumacs are some of this variety. The pith is so soft that you can actually poke it out with a stiff wire and have a hollow stick. Length is only dependent on how long a wire you use and how patient you are. This makes great stems for calumet pipes.

Al

[wade clark]

Hi Canadian,
As Al said, the center wood is the heart wood. When a tree was very new and little, the center wood was the sap wood, outer wood. Actually, there are 4 layers in a tree. Forgive me for over-simplifying or overstating the obvious, but here it is: The layers, from the outside in, are the outer protective layer of bark, the cambium layer, the sap wood and the heart wood. The cambium layer is the slippery wood just below the bark. It's the "most living" part of the tree, where all the growth really happens; it grows a new layer at this level basically every season...more correctly this layer is constantly transforming, fresh new wood- growing cambium layer to the outside and older cambium layer to the inside becoming sap wood, but growing at different rates at different times of the year and different temperatures with the seasonal changes causes "growth rings", visible as grain when the wood is cut.
The next layer in is the sap wood. The sap wood used to be cambium layer but as new cambium layer grew over it, its cell structure aged. The cambium layer is where the vibrant growth happens in a tree. Every layer is like a bundle of straws, kind of like bamboo shoots banded together. It has lots of "straws" with divided sections like bamboo. The cambium layer is vibrant and like a river flowing through those straws. The sap wood still has the same straw structure or cell structure it had when it was cambium layer, but it's aged and gotten harder, plus minerals have built up in it, blocking flow and hardening the walls and cells of the straws, and restricting sap flow, but storing sap as it slowly moves through the cells.
The very center of the tree was once the cambium layer of a very young sapling tree, vibrant with lots of sap flowing freely. A season later it was sap wood and there was new cambium layer over it, and a new layer the year after and so on. This very young tree was very small and its' straws and cells were very small as well. Each year, as the tree gets bigger, the cambium layer is bigger and develops bigger straws and cells, so the oldest straws near the center of the tree have very small cells compared to each year's cells forming later further out from the center. Those cells still "drink" and pump and store sap; they're still alive and well, but as they keep moving the sap, nutrients and moisture pulled from the earth, they also store minerals which block and harden the cells, as well as darken or stain them with the minerals. This stained inner wood becomes the "heart wood", the layer nearest the center of the tree. Used to be cambium, then sapwood, same wood is now heart wood, just older and stained with mineral build-up. It usually is harder because the cell structure was smaller and tighter, plus it's usually the prettiest wood because of the color caused by the minerals and ageing. There are of course exceptions to every rule in nature; some plants grow with pithy centers and lots of other ways, but most trees in the world pretty much grow with similar layers.
Heartwood is usually the more colorful harder wood nearer the center of the tree. Some times some trees will have mostly heartwood and fewer layers of sap wood; I don't think they ever have more than one layer of cambium, but not sure about that...it's constantly growing and evolving, that I know. Sometimes there's far more sap wood than heartwood. I suppose it depends on the variety of tree and the soil it's sitting in, since heartwood is primarily the sapwood colored or discolored by mineral build-up.
Older wood in the tree will have a tighter grain because it was from a smaller tree with smaller cell structure, before it got big.
I read all this on a link someone posted on hereabout a year or two ago and it clicked for me and made sense.
One more thing: If you harvest green wood to carve or store for carving later, the cell structure of the inner heart wood causes it to dry slowly, the large "straws and cells" of the outer sap wood causes it to dry very quickly in comparison. Because the outer stores far more water with its' large cells, when it dries it shrinks and cracks. The cracks can run clear to the center of the log once they get started, relieving stress in the wood. Moisture also evaporates out the sides of the log, causing more shrinkage, stress and splitting (called checking). Large saw mills where I grew up in Eastern Oregon's high desert ran sprinklers on top of the log piles any time the pipes weren't frozen, to keep the logs from drying too fast and cracking. You can do something similar with your green carving wood, or you can seal it with an end grain sealer like Anchor-Seal or wax -- I'd seal the entire piece, not just the ends, and re-seal if I saw any small cracks beginning, as often as needed. They say most woods dry at a rate of one inch per year! Yikes!!! I keep hoping they're wrong, but they speak with centuries of experience. Of course, kiln drying changes everything, but they rarely will kiln dry thick pieces of wood.
Most carvers prefer kiln dried wood and I'd recommend it, less problems to fight. But I usually carve green and fight the problems because I really like carving oak, sycamore and other hard woods and they carve much easier green.
Too much information, I'm sure, but hopefully you'll get some good out of it!
Have fun carving!
Wade