Results of experiment

[Backwoods Savage]

Many of you have read the thread: Wood shrinkage

In case you don't want to go back and read that thread, it was proposed by a neighbor (who also has worked with wood a long time) that my wood pile, although it had shrunk over the year, would gain in height over the summer. I highly doubted it but fully knowing how often I can be wrong, I simply made a couple of measurements on one wood pile.

This wood was stacked in April of 2009.

When I took measurements there were a couple places where it measured exactly 46" in height. Today I happened to think about it so this morning I took another measurement. It measured exactly 46". Another theory shot. Now I don't know whether to tell the neighbor the result or not for fear of insulting him! lol

btw, it has been brought up from time to time also about relative humidity and its effect on wood. One can certainly say that we've had some mighty high humidity for quite some time now too. Maybe I'll measure that stack a few more times before winter sets in.

 

[maplewood]

I've noticed mine shrink, and sometimes noticeably shrink more on the sunny side of the pile.
But I've never heard of or noticed them grow!
I would think that as the wood cells dry out and harden (and shrink) that they could soften again (punky) but not expand again.
That's my $0.02 from Eastern Canada.
Come January, it's ashes anyway!

 

[oldspark]

A lot of people have some "different" ideas about how humidity affects fire wood, I think maplewood got it right.

 

[Got Wood]

I do enjoy seeing those stacks - looks great.

Wouldnt it be great if we could actually grow our piles by stacking them for seasoning? Stack a cord and watch it grow .... LOL

 

[EatenByLimestone]

Welp, furniture can shrink and expand with the change in season. I don't see why firewood wouldn't. And the wood used for most furniture is supposed to be dried before you start making it.

Maybe since we spilt with the grain into quarters it moves less? I dunno. I'll leave that one for the teenagers who know everything.

Matt

 

[bogydave]

I made a workbench out of hard maple & cherry, (which was very dry & mad in the winter)
I made the apron & top free float on one side. It has moved (expanded) a few mm.
Bench was coated with urethane both side 4 coats each.
My point is, the expansion may be difficult to detect this small of movement.

 

[ironpony]

I have been watering my piles and no success in the growth rate
I'm just going to give up

 

[ckarotka]

I'm sure everyone has a wooden door in their house that "sticks" when it's hot and humid. Easy explanation, it expands. I believe that firewood is no different.

IMHO I also think the % of humidity in the air relates to drying/seasoning time. This is just a thought but, if the %of water in the air is higher than the % of water in the wood, it would "Push" in so to speak just like with that stupid interior door that sticks.

For fluid or gases to move there has to be a pressure difference. Nature wants things to be equal on both sides. So the greater moves to the lesser.

I'm having flash backs from patho/phys classes about homeostasis and osmosis. This I know: water follows salt.
So in the human body if you need more volume in your circulatory system "we" give fluid that draws more fluid into the veins and arteries that is from outside the vessels in your 3rd space because it has a higher molecule concentration and the body wants things to be equal. Thus increasing your volume of blood in the vessels, increasing your blood pressure pending that your heart is strong enough to do so. Trauma stuff.

To me it's all relative.

Eatenbylimestone, I thought I read a post that you were a fellow medic, help me out a bit, it's been a while since I cracked a book. My service is not permitted to give LR so all I've got is NSS so I might be a tad off on the explanation.

Like I said, just a theory or rather an opinion.

Charlie

 

[quads]

I'm sure everyone has a wooden door in their house that "sticks" when it's hot and humid. Easy explanation, it expands. I believe that firewood is no different.

IMHO I also think the % of humidity in the air relates to drying/seasoning time. This is just a thought but, if the %of water in the air is higher than the % of water in the wood, it would "Push" in so to speak just like with that stupid interior door that sticks.

For fluid or gases to move there has to be a pressure difference. Nature wants things to be equal on both sides. So the greater moves to the lesser.

I'm having flash backs from patho/phys classes about homeostasis and osmosis. This I know: water follows salt.
So in the human body if you need more volume in your circulatory system "we" give fluid that draws more fluid into the veins and arteries that is from outside the vessels in your 3rd space because it has a higher molecule concentration and the body wants things to be equal. Thus increasing your volume of blood in the vessels, increasing your blood pressure pending that your heart is strong enough to do so. Trauma stuff.

To me it's all relative.

Eatenbylimestone, I thought I read a post that you were a fellow medic, help me out a bit, it's been a while since I cracked a book. My service is not permitted to give LR so all I've got is NSS so I might be a tad off on the explanation.

Like I said, just a theory or rather an opinion.

Charlie

Once the tree has been made into firewood, and it's 'bodily fluids' have dried, it's 'circulatory system' doesn't function anymore. The door sticks because it does expand...a quarter inch over a 6 foot area. I believe my oak firewood does expand in the humid weather...one thousandth of an inch per split +/-. It certainly doesn't expand as much as it shrinks in the first year that it seasons.

 

[Rockey]

You cant really compare furniture or a door because they have already been brought into equilibrium with the surrounding air and any deviation from that will make it shrink and expand in order for it to try and stay in equilibrium with its surrounding air. If we are talking about green stacks of wood it will definitley shrink as it dries. I cant remember whether it is perpendicular or parallel to the grain that it shrinkls the most but does shrink in all directions. As to why BW results didnt correlate to the expected outcome - I have no idea. Maybe he used a wood measuring stick that shrunk a proportional amount.

 

[smokinj]

I'm sure everyone has a wooden door in their house that "sticks" when it's hot and humid. Easy explanation, it expands. I believe that firewood is no different.

IMHO I also think the % of humidity in the air relates to drying/seasoning time. This is just a thought but, if the %of water in the air is higher than the % of water in the wood, it would "Push" in so to speak just like with that stupid interior door that sticks.

For fluid or gases to move there has to be a pressure difference. Nature wants things to be equal on both sides. So the greater moves to the lesser.

I'm having flash backs from patho/phys classes about homeostasis and osmosis. This I know: water follows salt.
So in the human body if you need more volume in your circulatory system "we" give fluid that draws more fluid into the veins and arteries that is from outside the vessels in your 3rd space because it has a higher molecule concentration and the body wants things to be equal. Thus increasing your volume of blood in the vessels, increasing your blood pressure pending that your heart is strong enough to do so. Trauma stuff.

To me it's all relative.

Eatenbylimestone, I thought I read a post that you were a fellow medic, help me out a bit, it's been a while since I cracked a book. My service is not permitted to give LR so all I've got is NSS so I might be a tad off on the explanation.

Like I said, just a theory or rather an opinion.

Charlie

Once the tree has been made into firewood, and it's 'bodily fluids' have dried, it's 'circulatory system' doesn't function anymore. The door sticks because it does expand...a quarter inch over a 6 foot area. I believe my oak firewood does expand in the humid weather...one thousandth of an inch per split +/-. It certainly doesn't expand as much as it shrinks in the first year that it seasons.

Makes sense my bathroom door has been sticking again for the last few weeks solid wood.

 

[Danno77]

You cant really compare furniture or a door because they have already been brought into equilibrium with the surrounding air and any deviation from that will make it shrink and expand in order for it to try and stay in equilibrium with its surrounding air. If we are talking about green stacks of wood it will definitley shrink as it dries. I cant remember whether it is perpendicular or parallel to the grain that it shrinkls the most but does shrink in all directions. As to why BW results didnt correlate to the expected outcome - I have no idea. Maybe he used a wood measuring stick that shrunk a proportional amount.

and another way of looking at it is that firewood is 20%+ (as an example) and furniture, etc is gonna be less than 10%. which is gonna soak up more water...a dry sponge or a damp sponge?

 

[oldspark]

I'm sure everyone has a wooden door in their house that "sticks" when it's hot and humid. Easy explanation, it expands. I believe that firewood is no different.

IMHO I also think the % of humidity in the air relates to drying/seasoning time. This is just a thought but, if the %of water in the air is higher than the % of water in the wood, it would "Push" in so to speak just like with that stupid interior door that sticks.

For fluid or gases to move there has to be a pressure difference. Nature wants things to be equal on both sides. So the greater moves to the lesser.

I'm having flash backs from patho/phys classes about homeostasis and osmosis. This I know: water follows salt.
So in the human body if you need more volume in your circulatory system "we" give fluid that draws more fluid into the veins and arteries that is from outside the vessels in your 3rd space because it has a higher molecule concentration and the body wants things to be equal. Thus increasing your volume of blood in the vessels, increasing your blood pressure pending that your heart is strong enough to do so. Trauma stuff.

To me it's all relative.

Eatenbylimestone, I thought I read a post that you were a fellow medic, help me out a bit, it's been a while since I cracked a book. My service is not permitted to give LR so all I've got is NSS so I might be a tad off on the explanation.

Like I said, just a theory or rather an opinion.

Charlie

It almost sounds like you are saying the wood will not dry in the summer time when the humidity is higher than the wood, we all know that is not true so not sure about what you are saying with the pushing theory.

 

[Danno77]

humidity % and moisture content % aren't measured in the same ways at all, so it's not that easy to say "the moisture content of the air is greater than the wood" without doing some significant math....

 

[ckarotka]

What dries faster? I wet sponge in a sauna with 90% humidity set at 100*f or a wet sponge in an electricoven set at the same temp?
I'm not saying it doesn't dry. I think is slows it down that's really all.

 

[oldspark]

What dries faster? I wet sponge in a sauna with 90% humidity set at 100*f or a wet sponge in an electricoven set at the same temp?
I'm not saying it doesn't dry. I think is slows it down that's really all.

That's what you said? :lol:

 

[ckarotka]

These articles don't mention about speed of drying but, humidity does limit how dry it can really get under those high humidity conditions. I don't think after reading these articles that "we" as wood burners really have to worry about humidity.

Sorry for any raised feathers, but I tend to rationalize with commonsense first before looking at science.

These have some interesting info. Not sure how credible.

paragraph #4 and on
http://www.ukuleles.com/Technology/humidmath.html

http://www.hoganhardwoods.com/hogan/pages/technical/Technical_01/effectsofhumidity.htm

I'm doing a lot of searching to find a humidity vs time example to get some more info.

 

[Battenkiller]

I posted this stuff over on the "Shrinkage" thread on accident. I'm moving it over to this one.


With all due respect, Dennis, ash shouldn’t shrink anywhere as much as you mentioned in the other thread. Going from 54” high to 46” because of shrinkage of the wood alone doesn’t jive with my info.

White ash will shrink about 8% in the tangential direction (along the grain lines) and only 5% in the radial direction (across the grain lines) as it goes from green all the way to ovendry (0% MC). That would probably net about a 6% shrinkage in a stack of randomly oriented splits. In fact, almost all hardwoods shrink at the most about 10% along the grain and much less across the grain. Softwoods shrink even less. The 15% shrinkage you have measured has to come mostly from the settling of the stacks over time.

Still, I wouldn’t expect your stacks to ever get any taller, even after they have dried and settled. After a full year at the average RH in your area, it has probably gotten pretty close to 15%, and it will likely stay there for the rest of the time it is out there, +/- a few seasonal percentage points of MC.

BTW, in general, wood does not shrink at all in the longitudinal direction. Much less than 1% for normal wood.

 

[Battenkiller]

These have some interesting info. Not sure how credible.

Charlie, that is some seriously good info you just provided with that link. Musical instruments are my field, so even if folks here want to doubt it as regards to firewood, I'll be using it in my work. ;-)

 

[Delta-T]

I would guess that as the cell structure of the wood fails the capillary action of the water would slow down significantly and resist any moisture working its way back into the wood. Human water osmosis works through salt, plants generally use evaporation and capillary action to power their engines (when you think about it, a 100' tall tree must have some massive pressures going on in there suspending all that water in the wood fiber and pumping it from the ground up to the leaves and stuff). Water is weird stuff.

I think if it were possible to measure total volume of a wood pile you might find that it grows and shrinks, with more shrinking than growing, of course.

 

[Battenkiller]

I think if it were possible to measure total volume of a wood pile you might find that it grows and shrinks, with more shrinking than growing, of course.

I know for certain that it will only shrink until it reaches the highest seasonal equilibrium moisture content (EMC) of the area that it is stored in. After that, it will wax and wane in volume through the seasons, but by such a small amount that it would never be apparent in a wood stack. Even if your firewood varied from 13% and 17% throughout the year (which I sincerely doubt), it's pretty easy to see from the chart that CK provided that we're talking maybe a half percent difference in actual wood volume between the two extremes.

 

[Backwoods Savage]

With all due respect, Dennis, ash shouldn’t shrink anywhere as much as you mentioned in the other thread. Going from 54” high to 46” because of shrinkage of the wood alone doesn’t jive with my info.

White ash will shrink about 8% in the tangential direction (along the grain lines) and only 5% in the radial direction (across the grain lines) as it goes from green all the way to ovendry (0% MC). That would probably net about a 6% shrinkage in a stack of randomly oriented splits. In fact, almost all hardwoods shrink at the most about 10% along the grain and much less across the grain. Softwoods shrink even less. The 15% shrinkage you have measured has to come mostly from the settling of the stacks over time.

Still, I wouldn’t expect your stacks to ever get any taller, even after they have dried and settled. After a full year at the average RH in your area, it has probably gotten pretty close to 15%, and it will likely stay there for the rest of the time it is out there, +/- a few seasonal percentage points of MC.

BTW, in general, wood does not shrink at all in the longitudinal direction. Much less than 1% for normal wood.

Very interesting. Now please observe this picture very closely. Look at the very end of the stack that that ugly man has his hand on.

Now someone please describe for me exactly where and how the end of the stack has settled. The measurement was actually taken on the opposite side of the stack and it was measured from the bottom of the bottom split to the top of the top split. Notice I did not measure from the ground up because the saplings that the wood is stacked on have probably settled into the ground a bit.

 

[Backwoods Savage]

btw, probably nobody has noticed, but that is a Woodstock vest he is wearing. The logo does not show up good in this picture though.

 

[Delta-T]

perhaps your tape measure has lost a few MC% points and has shrunk? You may also have a classic infestation of Irish Wood Pile Brownies. These little guys come in at night and move splits around, they think they're funny, but they're not.
That is a really sharp lookin vest.

 

[Battenkiller]

Dennis, if we're gonna have an ugly contest, I'll win in a walk. I'm not only ugly, I'm fat and ugly.

Really, I'm not disputing your measurements at all. In my mind, however, I just can't account for them as coming merely from shrinkage. Dispute the established industry figures on wood if you will, but here is a very well respected table containing the amounts that most of the woods we are all familiar with actually change in dimension as they dry from green to 0% MC. Highlighted in yellow are three woods that I am very familiar with from stacking them for over 25 years. You don't have to accept this data if you choose not to, but there are dozens of similar tables that will corroborate what is shown in this one. I see no earthly reason why firewood would shrink more than dimensional lumber.

At any rate, one thing is sure in my mind. Once your firewood has shrunk, it basically stays that way. Isn't that what this thread is all about?