What is the Real Definition of Dry Wood?

[Gypo Logger]

Some people believe that it is the length of time that wood has seasoned as well as it's appearance that indicates whether wood is dry or not.
In other words, if wood is all dark and grey and cracked on the end grain, most think of this as an indication of wood with a low MC content and therefore burnable.
This is all fine and dandy, but mere appearance and length of time drying is absolutely no indicater whatsoever of burnability and moisture content.
Let's face it, anything will burn once a good bed of coals is established, but lets discuss all the variables that constitute what well burning wood really means.
The dryest wood is probably wood that has been winter cut and stored in a well ventilated barn where it never gets rained on and used the following winter, however, wood can be too dry and burning efficiency is lost unless your firebox can be virtualy starved for air.
I've noticed that wood felled and split on days where the temp is -15C or lower and burned that very moment does not contain much MC and has very good coaling qualities.
What other things have you all noticed about the burning qualities and factors that make good firewood?
John

 

[jp hallman]

Well now. The offical definition of "bone dry" is 17% or less. That's the gumment's ruling for biomass fuel. Tha's dry enough for any burning..."chemical reaction" to take place.

 

[ShoerFast]

Gypo

This may be an over simplfied system, but it works well for me.

When I sort firewood for retail, I found a system that just works better then trying to guess by the waight % size method.

If I just want to know if it's stove ready, I take about the most avrage - bigger block from the pile and rip the lenght of it with a chain saw,,,, so I get a good fist full of those real long shavings.

Fist up about a softball size loose pile and light it, if it goes "woof" it's less then 10% and like you said, maybe too dry for some, like open fireplace consumers. If it burns real well, with maybe a little white smoke from the middle of the flame, but reburns in the fring of the flame,,,, I think thats about as dry as most want it.

But if the white smoke (steem) will leave the flame, and it burns real slow and unevenly, that needs a little more time as it's maybe 17% - 20% + MC.


Kevin

 

[rmihalek]

I found that the bottom 3 or 4 feet of a tree (the base log or whatever you want to call it) is usually much more dense than the wood above and also burns longer and leaves better coals. Also, crotches tend to be very dense since I guess the tree adds extra strength to this area to support the limb. Crotches are a bear to split, but the wood is great for those long nighttime burns.

You might ask "how do I know which pieces are which?" Well, I process my own firewood and it's usually from tree length stock, so I get to see the wood in (almost) it's native state.

 

[musher]

Crotches are a bear to split, but the wood is great for those long nighttime burns.

No kidding! Even with a log splitter. I find splitting crotch wood to almost be an art in reading the wood grain to know just where to split it effectively.

 

[smcowboy1974]

Dry wood

My wood gets cut in winter of previous year and sold the next at minimum. So it's split and drying for at least 8-9 monthes or more. That all depends on when it gets sold!

 

[hautions11]

Dry firewood

I agree completely with Gypo's comment on cut one winter burn the next. My wood this year was over 2 years old. It looked nice, but ther was enough degredation in the wood itself, that the burn quality was lacking. It was certainly dry enough per the normal defanition.. ie wait a year. The shelf life is not as long as I would have expected.

 

[PLAYINWOOD]

John,wood is just like hay and needs two things to dry, wind and sun.Rain in my opinion just dampens the outside temporarily.I even split 3" stuff because the bark acts as a skin and needs to be broken.Yes I have burnt green white ash and I even threw a piece of newer red oak in 4 hours ago for a test.Wood is still there,but little or no heat emanating.In my house I want heat and longevity so I burn oak and maple exclusively ,cut and split and piled now for next year.Old farmers tale based on corn rows.Rows of wood no higher than 4 ft high and 2 foot gap between running east/west so summer afternoon sun gets to the bottom pieces.Row length can be infinity.Storing inside,in the woods,under a tarp in my experience seems not as beneficial but almost detrimental.If wood is burning fast because it's to dry,turn the stove down.

 

[Gypo Logger]

All very good points, however the word 'seasoned', is not as cut and dried as most would have you believe.
Wood not only gives up moisture, but it also absorbs moisture under certain conditions. I don't know of many firewood producers who take a moisture meter and wait for a magical 17% - 20 % figure to appear.
I'm not trying to be difficult or anything, I am just wanting to ponder all the suttle differences and factors that make wood burn, give up their moisture and the reasons why.
One of the biggest factors in wood burning efficiently is not neccessarily the MC, but rather the draft that is created with any given burning appliance at any given outside temperature.
The wood I am burning now is 50% greener than grass and 50% stored inside one year. This is the only way I can get the required longevity to have any coals in the morning and when I come home from work, even though I do my best to starve the stove for air.
John

 

[PLAYINWOOD]

John,just for interests sake what kind of stove and what kind of wood.

 

[Gypo Logger]

My stove is incredible, it's a side loader and air tight except for a gasket I should repair in the door. It has a draft like a torch. The wood I am burning is Sugar Maple. The supposedly green stuff I am burning is cuttoffs from the logs I felled last month when the sap was low.
I'm not inquiring about how to build a fire, rather I'm very interested in the MC content of wood and how it is suspended within the wood and how that effects it's burnability and how fast the vascular bundles within the wood give up MC and at which rate and why.
John

 

[ShoerFast]

Thats a heavy question John!

As I'm sort of from the school that "wood heats you twice" concept.

But there is something to it, as in any weather, oak dosant seem fully cured in a year, but the long grains of ash seem to be dry in a few weeks after it's split.

Tipping green trees with there leaves on and letting them sit before limbing, as the leaves seem to draw a lot of MC out seems to speed the prosses. But wouldent be dryer faster then winter cut trees.

What seems to speed the prosses after it's split and stacked is a few hard frezzes and thaws, almost as if the MC opens the fiber that it's in when it turns to ice crystals?

A big problim here is when live, thick , old growth gets below 10% MC, if a fire brakes out, and any wind and it cant be put out

Kevin

 

[scottr]

Water in wood

John , the moisture in wood that is in the cells is called free water , the moisture in the cell walls is called bound water . The free water is first to evaporate then the bound water .

 

[johnha]

I'm going to agree with Kevin that it depends on the variety of wood. If I want oak to be ready in a year, I have to split it into pieces of 2-3" thickness. Beech also needs a good full year.

I stack my wood in single stacks at least 4" off the ground and 4-6' high. I only bother to cover my piles with tarps if we're expecting two or more days of rain, and then I really only cover the top of the pile.

 

[Gypo Logger]

John , the moisture in wood that is in the cells is called free water , the moisture in the cell walls is called bound water . The free water is first to evaporate then the bound water .

That's totaly true, and the kind of thing I wanted to discuss. The tree, or piece of wood is not technicaly dead untill the cells that hold the water have collapsed. Once this has happened then the MC is free to migrate quickly from the wood.
It's a two edged sword, the bound mc in the cells prohibits water from entering, while wood with colapsed cells can absorb water readily.
John

 

[scottr]

Drying

John , the wood does not shrink when the free water is evaporated but shrinks when the cell walls dry below the fiber saturation point . I've seen charts on drying lumber that show time vs. moisture content in lumber and the free water is evaporated fast similar to the top 2/3 of a bell curve and the bound water is slow to evaporate as in the bottom 1/3 of the bell curve . Thicker cell walls take longer to migrate the moisture from one cell wall to the drier cell wall . Then different woods like ring porous and diffuse porous dry at different rates . If you'll look at the Wood Handbook chapter 3 in the us.fs. website it explains it much better than I can . It is very involved . Have you ever heard the term partially air dried firewood ? From what I've read it's firewood that has less than 25% moisture content .

 

[Big Woody]

The tree, or piece of wood is not technicaly dead untill the cells that hold the water have collapsed.

Wow, I wonder if this would apply to people as well. Sounds like a good defense stratagy.

 

[woodfarmer]

green wood

gyp, do you not worry about creosote with the green wood, i try to keep two years ahead, burn mostly beech as it is in my opinion the best firewood and most of my beech trees are dying, i sell the maple as that is what most people around here deem to be the best firewood.

 

[Derag2]

This is our first year burning wood, but all we do is cut and split and put it in a pile, we havn't stack hardly any of the wood, guys we talk to around here don't stack It either just leave it in a pile.... All we look for is under 20% MC with a meter and color it done, Works just fine. We are dang near 2 years ahead of the game already....

 

[manual]

try this for some info on seasoned wood.
http://thechimneysweep.ca/6seasoningwood.html