Ha! If a hen and a rooster both lay an egg on the peak of East/West facing barn roof, which way will the eggs roll???Which weighs more - a pound of green wood or a pound of dry wood?
Hint: don't eat the rooster eggs.Ha! If a hen and a rooster both lay an egg on the peak of East/West facing barn roof, which way will the eggs roll???
Yep, I'm one of those that say that... but I believe there's a bit more than "perception" involved.Some people on here claim that standing dead elm with bark falling off burns better than bark on elm that is cut green then seasoned.
Hard to say.
But burn rate has something to do with the "perceived btu output" too.
Once combustion starts the reaction wants to complete quickly. If one wood burns slower think of it in terms of what is inhibiting fire. Density of fuel has some to do with it but it's primarily because of moisture content. Many seasoned woodburners will complain that Oak stored over 4 years will burn too fast.Tamarack has a btu rating of 19.5 but burns really fast. Red oak has a rating of 22.1 but burns slow.
Whitespider, how does that theory "stack up" with the observation that the bottom of a standing dead Elm contains more water than the top? Does the bottom of the tree shrink once its dried?I think of a dead wet wood like a wet sponge. If you hold the wet sponge by a corner and let the water run out of the pores, air displaces the water and the sponge shrinks very little. But if you seal the wet sponge in plastic (representing the bark of a tree), cut a small hole in one corner, hold the sponge by the opposite corner and let the water run out of the pores, air cannot displace the water and the sponge shrinks-up tight.
Whitespider, how does that theory "stack up" with the observation that the bottom of a standing dead Elm contains more water than the top? Does the bottom of the tree shrink once its dried?
On that note I cut some standing dead, bark off sugar maple. That stuff was rock hard, heavy, and sparks were flying from the chain as I cut it. So I'm thinking this may have a similar shrinkage/compaction factor.Yep, I'm one of those that say that... but I believe there's a bit more than "perception" involved.
The wood from standing-dead elm (standing-dead long enough for the bark to fall) is harder, denser and heavier than elm cut green and seasoned. I have a theory about why that is (and it's only my theory)... I believe the wood shrinks-up tighter as if "drys" on the stump.
I think of a dead wet wood like a wet sponge. If you hold the wet sponge by a corner and let the water run out of the pores, air displaces the water and the sponge shrinks very little. But if you seal the wet sponge in plastic (representing the bark of a tree), cut a small hole in one corner, hold the sponge by the opposite corner and let the water run out of the pores, air cannot displace the water and the sponge shrinks-up tight. If you've ever had an elm die in your yard where you can watch it, touch it every day I think this would make more sense. The bark stays tight to the trunk for some time, and then, about the time a few small branches begin to fall, the bark suddenly "goes loose" almost overnight. So loose there will be a full inch or more of "gap" between the bark and wood all the way round the trunk. Once dead, I believe the roots do allow water to drain from the tree... and they also allow water to be pulled up into the tree (like a sponge would do). I base this on the fact that standing-dead elm trunk will be dry all the way to the stump during "drought" years, but wet as high as 12-15 feet during "wet" years.
Now here's the thing...
The tree only contains so many pounds of wood. Whether it dies and drys on the stump or you cut it green and season it the total weight (mass) does not change... meaning the total (potential) BTU content does not change.
But what the "shrinkage" does change is the total volume of the tree, or the space it uses... meaning you'll have more pounds to the cord, but fewer cords from the same tree(s). You do end up with better firewood... just as oak is a better firewood than soft maple... because when you fill the firebox you can fit more pounds of it in there. On a BTU-per-pound scale, wood is wood; ten pounds of wood, any wood, contains the same BTU's... the only difference between oak and soft maple is the volume, or the space that ten pound consumes. So along that line of thinking (perception??); if oak is a "better" firewood than soft maple, than bark-off standing-dead elm is a "better" firewood than elm cut green and seasoned... correct??
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I'll bet that someone at the USFS has studied this.
Very informative, stuff I didn't know. Thanks.I doubt it makes any difference… because energy (mass) cannot be lost, it can only change form.
There are two kinds of sap in a tree.
The sap moving up from the roots through the center of the trunk/branches is mostly water and dissolved minerals/nutrients from the earth, it feeds the leaves. The leaves use photosynthesis to convert the minerals/nutrients into sugars, which flow back down just under the bark, feeding growing parts of the tree that cannot photosynthesize. Your firebox cannot burn water and minerals (the inner sap) so that means nothing to the recoverable BTU’s in wood. In fall/winter, when the roots stop feeding the leaves, causing them to shrivel and die, the sugars remaining in the outer sap is not wasted (that would be a stupid life design, don’t ya’ think?)… it is either stored (such as maple trees) to make new leaves in the spring and/or utilized by the tree to make more wood/bark/roots/etc. The (now) thicker (because of less water) sap also acts as a natural anti-freeze to protect the tree as it over-winters.
Really, the only thing that changes is the moisture (water) content of the remaining sap as the tree enters winter hibernation… simply because the tree doesn’t require as much moisture during hibernation. It may also dump any excess water and minerals/nutrients (that you can't burn) from the tree center back out through the roots, but the tree ain’t gonna’ dump any sugars it worked so hard to create… it just stops pulling in water and minerals your firebox can’t use anyway.
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