RE: Article in the local newspaper about burning unseasoned wood

[firefighterjake]

http://morningsentinel.mainetoday.com/news/local/7218369.html

I did have a few "issues" with the article.

1) Warm temps are not necessary critical for seasoning . . . as we have discussed here wood continues to season right through the winter cold.

2) If someone is burning unseasoned wood I would not wait until Christmas to check and clean the chimney as the article suggests . . . but would say sooner is always better than later.

 

[mellow]

http://bit.ly/5g7zeF

Created a short link to that article, I sent it to a few friends that swear burning green wood is OK. They have done it for the past 20 years and do not want to change, I figure if they don't believe me maybe they will see that I speak the truth if it comes from people living in Maine who burn a heck of alot more wood than we do here.

 

[cycloxer]

That's why I have three storage locations for my wood:

1.) Long term supply stacked as 4x8x4 cords with a waterproof tarp covering the top. This is my biggest location outside.

2.) Medium term supply stacked as a face cord under a roof overhang. Stays 100% dry and gets wind and sun.

3.) Short term supply stacked inside at room temperature, rotated, about 1 week supply.

Someday I will build a wood shed, but with this method I can dry out my wood much quicker than just leaving it in a pile in the driveway. I'm burning red maple I split this summer just fine. The dryer and warmer you keep your wood, the faster it dries out. This is not rocket science. Also, if you have an indoor storage location your wood will dry out even faster during the winter due to the low humidity.

The main problem is that people don't spend the effort to split their wood to the proper size and then they don't stack and store it properly. Garbage in = garbage out. Cold, wet, snowy wood does not dry out.

 

[Backwoods Savage]

Neither link worked for me.

 

[Rockey]

http://morningsentinel.mainetoday.com/news/local/7218369.html


1) Warm temps are not necessary critical for seasoning . . . as we have discussed here wood continues to season right through the winter cold.

Correct. It just seasons much quicker with more heat. Warm temps are critical for quicker seasoning

 

[cycloxer]

Correct. Warm, dry air speeds up the process. Hang a pair of wet jeans outside on the clothes line in the winter and then go hang a pair inside and tell me which one dries faster. Wood is no different.

 

[LLigetfa]

Wood is no different.

Last I checked, wood makes lousy clothing. Clothes on the line has its moisture close to the surface, unlike firewood.

 

[cycloxer]

Explain to me how water comes out of firewood during the drying process. Also, explain to me what is this kiln dried firewood. How do they make that?

Okay I'll be nice. During the winter, the water in your firewood stored outside is frozen when the temperature is below 32. Once that happens, the water can no longer evaporate. However, your wood can still dry outside due to sublimation - the process where the ice bypasses the liquid phase and goes directly to the gas phase as water vapor. Unfortunately, sublimation is not nearly as speedy and efficient as evaporation.

That's why with the analogy I used about a wet pair of jeans, the pair left outside will still be frozen solid, but the pair inside will dry in less than a day. Eventually, if the humidity is low enough, the frozen water in the pair outside will sublimate and your jeans will dry, but it will take awhile.

Drying out wood is no different. You need to get the water to turn into a gas in order to make it go away. If you put it in a kiln where you increase the temperature and airflow, you speed up the process.

So my point was that wood put inside your warm, dry house will dry out much faster than in your outdoor frozen wood pile.

 

[CarbonNeutral]

Explain to me how water comes out of firewood during the drying process. Also, explain to me what is this kiln dried firewood. How do they make that?

Okay I'll be nice. During the winter, the water in your firewood stored outside is frozen when the temperature is below 32. Once that happens, the water can no longer evaporate. However, your wood can still dry outside due to sublimation - the process where the ice bypasses the liquid phase and goes directly to the gas phase as water vapor. Unfortunately, sublimation is not nearly as speedy and efficient as evaporation.

That's why with the analogy I used about a wet pair of jeans, the pair left outside will still be frozen solid, but the pair inside will dry in less than a day. Eventually, if the humidity is low enough, the frozen water in the pair outside will sublimate and your jeans will dry, but it will take awhile.

Drying out wood is no different. You need to get the water to turn into a gas in order to make it go away. If you put it in a kiln where you increase the temperature and airflow, you speed up the process.

So my point was that wood put inside your warm, dry house will dry out much faster than in your outdoor frozen wood pile.

I would agree with this - and hypothesize that anything dries faster the lower the relative humidity - outside in winter the relative humidity around here still floats at 50% or more, inside, with a similar amount of moisture, but higher temps, the rel humidity is much lower. I would figure this would cause better drying.

 

[cycloxer]

and hypothesize that anything dries faster the lower the relative humidity

Yes, absolutely. That is why if you have ever been to Arizona it seems that no matter how much water you drink, you always feel dehydrated. You are literally evaporating in the dry desert air. The lower the relative humidity of the air, the easier it is for water to evaporate. This is another reason why wood dries faster inside your house with the dry winter air. If you have wood floors in your house you know that they shrink in the winter months and swell during the summer months.

 

[littlesmokey]

So how do we get freeze dried food????? :-S

 

[jadm]

So how do we get freeze dried food????? :-S

Look for frozen snakes, mice or squirrels in your outside wood piles. :cheese:

 

[cycloxer]

So how do we get freeze dried food????? :-S

The process for preserving food involves freezing the food and then using a vacuum chamber to remove the frozen water. Heat is applied to speed this up. This is also a sublimation process.

 

[weatherguy]

That answers a lot of my questions. I have a big outdoor pile covered with a tarp, then I have about a cord at all times in the garage, garage is uninsulated and stay a bit warmer than outside, and of course dry, then I have a big bin loaded with wood inside. The wood just works itself right down the line, (a little help from me actually), seems to be working well.

 

[fraxinus]

Maybe it's time to require firewood dealers to at least tell their customers what they men by "seasoned" wood. Split for how long? There was a local TV news interview with dealer who was bemoaning the poor drying weather of this past summer. During the course of the interview it became obvious that the wood he normally sold as seasoned was split in the spring and sold in the fall. There were also a lot of ads this past summer for "partially seasoned" wood. What does that mean? If you cut the tree on Monday, I guess it would be "partially seasoned" by Tuesday.

 

[quads]

Explain to me how water comes out of firewood during the drying process. Also, explain to me what is this kiln dried firewood. How do they make that?

Okay I'll be nice. During the winter, the water in your firewood stored outside is frozen when the temperature is below 32. Once that happens, the water can no longer evaporate. However, your wood can still dry outside due to sublimation - the process where the ice bypasses the liquid phase and goes directly to the gas phase as water vapor. Unfortunately, sublimation is not nearly as speedy and efficient as evaporation.

That's why with the analogy I used about a wet pair of jeans, the pair left outside will still be frozen solid, but the pair inside will dry in less than a day. Eventually, if the humidity is low enough, the frozen water in the pair outside will sublimate and your jeans will dry, but it will take awhile.

Drying out wood is no different. You need to get the water to turn into a gas in order to make it go away. If you put it in a kiln where you increase the temperature and airflow, you speed up the process.

So my point was that wood put inside your warm, dry house will dry out much faster than in your outdoor frozen wood pile.

If you are far enough ahead in your wood supply, you won't need to worry about it. You'll most likely need dry jeans sooner than the time it takes to season firewood, regardless.

 

[cycloxer]

If you are far enough ahead in your wood supply, you won't need to worry about it.

Yup, I can't argue with that one. If you give your wood one full calendar year, with the exception of some oak, it is usually ready to burn. I was mainly trying to provide some info on things you can do to speed up the wood drying process for those who are sitting there with huge piles of 'partially seasoned' wood, wondering how they are going to get it to burn effectively this winter in their new EPA stove. We know there are a lot of them out there...

Anybody can go buy a maul from HD and start double-splitting their not-fully-dry wood to increase the available surface area and then stack it inside to speed up the evaporative drying. It just takes some work.

My mother used to put my jeans outside like that, frozen like boards, so I know how much it sucks ;^)

 

[73blazer]

Maybe it's time to require firewood dealers to at least tell their customers what they men by "seasoned" wood. Split for how long? There was a local TV news interview with dealer who was bemoaning the poor drying weather of this past summer. During the course of the interview it became obvious that the wood he normally sold as seasoned was split in the spring and sold in the fall. There were also a lot of ads this past summer for "partially seasoned" wood. What does that mean? If you cut the tree on Monday, I guess it would be "partially seasoned" by Tuesday.

A whole summer, that's doing good by most people in this area. Last year, before I bought my moisture meter, I wanted to see how dry my wood really was by comparing it to known dry wood, and called like 3 or 4 firewood places looking for seasoned wood (this was in, I think it was late October) . When I asked if the wood was seasoned, ALL of them said, oh, yeah, it's not just seasoned, it's WELL seasoned. Then I asked, when was it cut and when was it split. I got varying answers on this, but nobody had the wood split longer than 2 weeks. It was quite funny to listen to them boast about their seasoned wood, "I deliver to alot of people and not one of them has complained." "It as dry as it gets, these trees were cut 2 months ago and split last week."

I hung up and went online and promptly bought a moisture meter instead. My wood was 25% or so, far better than those firewood places would have been.

 

[Battenkiller]

My mother used to put my jeans outside like that, frozen like boards, so I know how much it sucks ;^)

I remember that as well. If you brought in a frozen towel, you could snap it in half if you weren't careful.

Still, when the stuff thawed out, it was always nearly dry. Mom used to like the coldest nights as she said the clothes actually dried better. Anecdotal evidence for sure, but I never remember putting damp clothes on in the winter, so obviously, some sort of non-vacuum freeze drying occurred. I have always felt that green wood dries much faster after it has been subjected to several deep-freeze cycles (below 0ºF). Anecdotal again, but I've been burning for over 20 years, so there must be at least a little something to my observations.

I always purchase unseasoned wood late in the fall and let it dry through a variety of methods. I ordinarily buy only ash and cherry and pay a premium for it. I just got 2 cords of hickory (another low moisture content wood) which will burn OK for me by February, just when I need the extra heat it will give me the most. Wood supposedly needs at least a full year to fully season, but some woods (like cherry) will initially drop moisture content very rapidly. All wood dries at a slower rate as seasoning progresses, so after about two months, you start to get a diminishing return for each month spent seasoning. I notice this when I grab a piece of firewood to rough turn a bowl on my lathe. I get soaked from the wood when it is first delivered, but after a few weeks, it doesn't spin out enough water to really wet me. The wood starts to come off in chips rather than in long strings, and they aren't as cool feeling as they hit my hand (a sign of drier wood). They will still check and crack if I don't put them in a bag to dry slowly, but much of the free water has disappeared.

Another thing to understand is case hardening of wood. Woodworkers who use air-dried hardwood are acutely aware of this problem. If you go out in the summer and cut and split a bunch of wood, then stack it in the hottest, driest and windiest conditions summer has to offer, chances are that it will undergo a process whereby the outside of the wood quickly dries to an almost impermeable case around the outside. Eventually, the stresses produced by the differential drying rates will literally pull the wood apart. When that happens, deep cracks will develop and further drying will occur. In time, the wood will reach equilibrium with ambient relative humidity for that time of year, but it may take longer than you think. Most commercial kilns solve this problem by maintaing a very high relative humidity inside the kiln during the initial drying period. That tells me that maybe the best time to cut and stack your wood might be on hot muggy days instead of the driest ones.

I always ran my old stove as hot as I could get it. Once I started doing that, my chimney sweep stopped yelling about all the creosote. I mix in some really dry wood from the year before - about 20% - when I am going for a long burn (to keep the temps high enough), but when I am awake and around the house I burn the straight semi-seasoned wood. The wood I'm burning right now is cherry that was on the stump less than two months ago. I can easily get the stove temps up to the desired range (and beyond if I'm not careful) with this "green" wood. Little or no sizzling, and even the bigger pieces catch immediately once the stove is running at it's proper level with a good charge of wood. Yeah, I know I lose some heat in evaporation of the remaining moisture, but there's plenty of moisture remaining in wood that has been seasoned even for three years. Among woodworkers, we say "one year per inch thickness" as the time need to air dry wood to the equilibrium MC. How many folks burning those huge splits and rounds we see here have seasoned them for 8-10 years? I'd be curious to know what the MC of a 10" round of three year old red oak is on the inside.

As for me, as long as I'm getting it hot and keeping it up there, I think that's about all I can ask for from my firewood. My new stove settles in at about a 300-350ºF flue pipe temp (600-650ºF stove top temp) with the damper shut regardless of whether I am using straight seasoned or straight semi-seasoned, so I could care less about the extra wood I burn. Maybe an extra face cord or two a year. That's worth not have to move around an extra 5-10 cords of wood every season, or having to have almost 15 cords on my property to get at some three year old stuff.


Burning pellets is easiest, then I imagine those compressed wood bricks are a close second. Burning seasoned wood is a skill. Burning green and semi-seasoned wood is an art. Burning wet red oak takes a miracle.


Just my five cents (hey, I'm feeling generous this morning).

BK

 

[cycloxer]

Battenkiller - that is some great info.

I pretty much burn the same way at 600-650 degrees stove top. It is definitely a skill. Everybody has their personal technique, every stove is different, and every wood is different. Almost all of my red maple I cut in the spring/summer and start burning in the fall. The stuff I split myself, I split pretty small. It almost burns itself by the time it goes in the stove. It is a pretty forgiving wood in that regard.

I don't try to burn wet oak. That is futile.

 

[ROYJ24]

Explain to me how water comes out of firewood during the drying process. Also, explain to me what is this kiln dried firewood. How do they make that?

Okay I'll be nice. During the winter, the water in your firewood stored outside is frozen when the temperature is below 32. Once that happens, the water can no longer evaporate. However, your wood can still dry outside due to sublimation - the process where the ice bypasses the liquid phase and goes directly to the gas phase as water vapor. Unfortunately, sublimation is not nearly as speedy and efficient as evaporation.

That's why with the analogy I used about a wet pair of jeans, the pair left outside will still be frozen solid, but the pair inside will dry in less than a day. Eventually, if the humidity is low enough, the frozen water in the pair outside will sublimate and your jeans will dry, but it will take awhile.

Drying out wood is no different. You need to get the water to turn into a gas in order to make it go away. If you put it in a kiln where you increase the temperature and airflow, you speed up the process.

So my point was that wood put inside your warm, dry house will dry out much faster than in your outdoor frozen wood pile.

Just burn your pants!

 

[jkupcha]

Hey Roy
Where do you live in South Jersey? I'm down here in Mantua. The heart of red oak country. Nice to be able to find a cord of red oak delivered for $150.

 

[Battenkiller]

Battenkiller - that is some great info.

Glad to be able to contribute a nugget or two when I can. So much valuable info from a lot of serious burners, even several experts and pros in the field. Such a great resource here!

This is something I found today about the freeze-dry thing. Not exactly talking about firewood, but the concept is well known:

FREEZE DRYING

Freeze drying is used with some regularity of small pieces of wood, but the only limitation is access to the properly sized freeze-drying container (Ambrose 1970, 1975; Rosenquist 1975; McCawley et al. 1982; Watson 1982). In the past, the main problem that presented itself was the tendency for the surface of the wood to check and crack. This is caused by the ice crystals expanding and damaging the cell walls. Ambrose (1970) found that if the wood is pre-treated by soaking it in a 10 percent solution of PEG 400 until it is saturated, the formation of ice crystals during the freeze-drying process is essentially eliminated. This pre-treatment has become a standard element of the freeze-drying method for wood, as well as for leather. In addition to inhibiting the formation of ice crystals during freeze drying, the PEG introduced into the object during pre-treatment will act as a humectant after treatment and prevents the wood from undergoing excessive shrinkage.

More recently, Watson (1987:274-275) observed that a 20 percent or higher PEG solution will dehydrate and kill any microorganisms present in the solution through osmosis. He recommends using 20 percent PEG 400 for mildly degraded wood and 10 percent PEG 400 + 15 percent PEG 4000 for more degraded pieces. For severely degraded wood, the PEG 4000 may be increased to up to 25 percent, but treatment time is increased when PEG 4000 is used. If a PEG solution of less than 20 percent is used, a fungicide, such as 1 percent borax/boric acid or Dowicide 1, should be mixed with the PEG solution to stop any slime or mold from growing in the solution during pre-treatment.

Following pre-treatment with PEG, the wood is frozen in a domestic freezer. After freezing, it is recommended that the wood be placed in a freeze-drying chamber at a temperature of -32 to -40°C, and a vacuum applied after the temperature of the wood reaches -25°C. During the process, the frozen ice crystals sublimate, and the water vapor is frozen onto the condenser coils. This continues until all the water is removed, which can be determined by weighing the piece being treated. The treatment is completed when the weight loss stabilizes. After treatment, the wood should be stored in a relative humidity of 45-60 percent. Freeze drying as described here and in the chapter on leather is essentially the same when treating any waterlogged organic material. (See Watson 1987 for additional details.)

Although the freezing can be done in a chest freezer, like biological specimens, a quick freeze is best. This can be achieved by immersing the wood in a container with acetone and dry ice (frozen CO2). Some acceptable results have been achieved using non-vacuum freeze drying in a domestic freezer (particularly frost-free freezers). When a domestic freezer is used, the pre-treated wood is placed in the freezer and left there until it is dried. In this non-vacuum process, treatment times are in terms of months, as opposed to weeks in a vacuum freeze drier (McCawley et al. 1982).

Of all of the treatments discussed in this section, freeze drying is the most expensive due to the high cost of freeze dryers. Because of the size limitations of most freeze dryers, and the substantially higher costs when investing in equipment capable of treating larger objects, freeze drying is restricted to small objects in most laboratories.

http://nautarch.tamu.edu/crl/conservationmanual/File6.htm#Freeze Drying of Waterlogged Wood


Items in bold are ones I found interesting.


What's bad for wood conservation may be good for drying firewood. Seems those multiple freeze-thaw cycles do a number on the wood structure, cracking it more and more each time. This is essentially what I have observed myself. A few weeks of bitter cold nights (almost always very low outside humidity then as well), followed by warmish days have always yielded a significantly improved burn in my experience. I leave the green wood right out there until mid-February... right when I need it most. Bring in about a weeks supply inside and stack it 3' from the stove, rotate in a new day's worth every day. Burn it hot.

Been doing it for a very long time with great results - hot stove, good flame... cozy home with no other heat source.

Of course, you really have to be living in an area that sees lots of sub-zero weather. I notice a lot of southern burners here. My advice to them is to season for two years, since most stoves cranked the way I do mine would drive a southerner right out of their house.

 

[WoodNewbie]

The graph below says it all