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Does wood season quicker in winter, since it’s dry? Weird...

Post in 'The Wood Shed' started by thinkxingu, Jan 1, 2010.

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  1. iceman

    iceman Minister of Fire

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    it depends on location did you read that part? and you specific climate.. kiln dried would be the "perfect setup" is that what you have in your wallet/ backyard? :) most people agree that you need air movement/wind... these arent in the kiln dried.. how many hours does one have at 140 in the own backyard???? if i have 40 degrees of dry air with a breeze that will not cause evaporation? .. when does wood dry fastest??? --- it depends on YOUR specific location and climate conditions....
    for you it is summer ... and maybe many others for for some it could be in the fall... over here where i am.. our summers, when it gets real hot are just about always humid... the weather alert stay inside humid. about mid sept dry air comes in.. now there are some who live up in the mountains or people who have huge fields to maximize sun exposure but for the most part, we got a lotta trees and mountains/hills

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  2. Rockey

    Rockey Minister of Fire

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    I can see your failing to grasp the concept here that for a given rise in temperature there is a proportionally equivalent drop in seaoning time needed. Your opinion will always be right as long as you ignore the facts. If you really believe that in YOUR location that wood dries faster in the winter than in in the summer because it is humid in the summer then you need to ask Santa Clause to bring you some kiln dried firewood, because your firewood flat out wont season as fast in the winter. I honestly think that most people with marginally seasoned wood this time of year want to convince themselves that it is seasoning faster to make themselves feel better. The others are just wrong.
  3. thinkxingu

    thinkxingu Minister of Fire

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    ihookem mentioned a cup of water dries more quickly in summer than in winter, but that's not the case here in Southern New Hampshire. Case in point: in summer, if I don't use a fan in the bathroom we get tons of condensation. In winter, I don't use one because the air is so dry it just absorbs the moisture.

    So, if the air is dry, it will absorb much more moisture. SO, what's more important dry air and wind or sun and heat? Of course, if the water is frozen in the wood it probably won't go to far.

    S
  4. woodgeek

    woodgeek Minister of Fire

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    Lots of physical chemistry flying around this thread! The answer, of course is that the evaporation rate is proportional to the difference in partial pressure of H2O. Look up the vapor pressure of water as a fn of temp, it is about 3x higher at summer temps than winter temps. The pressure of the water vapor in the air is that number X the relative humidity (RH). Near the vapor source, the air is saturated (100% RH for that temp), and the difference in vapor pressure is what drives the flow of water into the ambient air. Period.

    So, that factor of 3x versus temperature can be compensated by differences in RH of outside air. The drying RATE in winter at 40% outdoor RH, and the rate in summer at 80% RH would be about the same (60% RH difference vs 20% RH diff). At night in most locations the RH goes to 100% as temp falls, so most drying is in the daytime (whether the sun shines on the wood or not).

    This also explains why indoor winter drying is so effective--high temp and low RH 24 hours of the day. We should expect 3x faster rate due to high temp and low humidity, and another factor of 2x for 24 hour versus 12 hour drying. A week inside can dry wood as well as 6 weeks of dry summer days, or maybe 8-10 weeks of actual summer weather. Seems about right in my experience--I can (at least adequately) burn almost any wood that's been sitting in my house for two winter weeks--equiv to a full summer of outdoor seasoning.

    Fact is, though, on many days no drying occurs (due to high RH during rain or snow)--how fast your wood dries during your different seasons depends on the statistics of your climate. If you have dry summers, rainy falls and really cold/stormy winters (NE and upper midwest) you will say that most drying happens in the summer. If you have humid/rainy summers, dry sunny falls and moderate winters (mid atlantic through lower midwest), you will find lots of drying happening in the fall and winter.
  5. iceman

    iceman Minister of Fire

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    so in the end it depends on "the individual location, climate etc" over where i am we get more "ideal weather for seasoning" from about mid sept on thru mid dec.... and also i would say may-june are the prime months for us.. and actually jan is good too sometimes BUT all this is subject to change ... hell we could have a drought this summer and it would season better in the summer this year..... and get a lotta snow next year .. it always change....
    at the end of the day.... wood can season in the summer (as we know) but also in the winter

    rockey i dont disagree that wood will season in the summer and i don't diasagrre it will season fast given the right setup, i am simply making a case that for us over here we get can get as much seasoning in the winter as summer because of our climate maybe more depending on the weather for the given season... if you notice the op is from southern new hampshire which he is prolly about an hr north of me possibly in the mountains, i am in the valley so typically in the summer since we are in the "bottom are dewpoints and rh are higher
  6. Wood Duck

    Wood Duck Minister of Fire

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    Your bathroom fogs up in the summer because the air in the house is more or less at the same temperature as the humid outdoor air, so the relative humidity remains high indoors, and when you add a bunch of extra humidity from a hot shower, you overload the air and get condensation. On the other hand, in winter your house contain air that is much warmer than the outside air. Even though the RELATIVE humidity outside may be fairly high the ABSOLUTE humidity or moisture content is low because the cold air can't hold much moisture. When you warm up the outside air, the air's capacity to hold moisture increases dramatically and the relative humidity drops even though the absolute moisture content remains the same, or even rises. This means the indoor air can hold lots of extra moisture from the steamy shower and you don't see as much condensation. If you are attempting to season your firewood indoors in the winter, I am sure it would season fast, possibly faster than summer outdoors.

    Outside right now at my place the wind is howling through the holz hausens, but at 14 degrees F I don't think there is enough energy to evaporate a lot of moisture. In this case instead of evaporating liquid water, seasoning would require sublimation of solid water directly to a vapor, which takes even more energy than evaporation of liquid.
  7. DBoon

    DBoon Minister of Fire

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    Just got back from checking my meadow-drying hickory. Since November 1st, moisture content has dropped from 27% to 22%. See this thread for more detail http://www.hearth.com/econtent/index.php/forums/viewthread/44360/

    So it appears that in two months of what would be considered cold and cloudy weather, with humidity at low levels in the last month (month of December) along with below zero temperatures and very strong winds, the wood continues to dry.
  8. Adios Pantalones

    Adios Pantalones Minister of Fire

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    Sublimation is a slower process than evaporation. Remember- in the winter the water is turning from ICE to vapor- not from liquid to vapor. Also- when water leaves from surface fibers, the water in the middle is not so mobile and doesn't redistribute so quickly in ice form- but it does if it's water at warm temps.

    Whether the air has a lower RH or not- the process comes to equilibrium much more quickly at a higher temp. While the factor of the wood getting rained on is an important one, however- that cellular water getting out is more important than that extracellular water getting in, particularly for oak.

    Wood dries in the winter, but much-much faster in the summer in my experience- and location.
  9. Adios Pantalones

    Adios Pantalones Minister of Fire

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    LOL at DBoon's avatar- "Bob Dylan wrote propaganda songs!"
  10. DBoon

    DBoon Minister of Fire

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    Yes, that's correct Adios. From the "What Makes a Man Start Fires" album. Good eye.

    Just for the record, I have a lot of Bob Dylan albums also.
  11. iceman

    iceman Minister of Fire

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    this is one of those arguements that there really is no one wrong due to to many different variables, one thing we do know is wood does dry in the winter and the summer... anything after that is null n void... without doing an experiment of 'weather ' conditions... ie finding days of rh with sun and breeze at 70 degrees vs i dunno 40 degrees super low rh and breezy... i am sure if i had an open field where i got maximum sun/wind i would be on the other side.... but here i get most of mine in the fall/winter due to weather conditions .. most times... this past year we prolly all got it in fall caused it rained so much this past summer!!...
  12. Green Energy

    Green Energy Feeling the Heat

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    Woodgeek is absolutely correct that the driver for drying wood or anything is the partial pressure of H2O in the ambient air. It is also true that when water goes from solid or liquid state to vapor, it absorbs heat. However, it is the partial pressure of H2O that is the prime mover. At 100 percent RH air, nothing transfers liquid (or solid) water to that air. The reason that heat works wonders in kiln drying is that it lowers the RH of the air making the water carrying capacity of a cubic foot of air even greater. In the summer, the dew point in my area gets into the 60s and sometimes into the lower 70s on humid summer days. On a summer night, when the dry bulb temp equals the dew pt: RH = 100% by definition. At 100% RH, zero drying occurs. However, during the day, when temps go into the 80s or 90s, RH can go down into the 50% range, upper 90s, RH that was at a 100% at 72, is now in the 30% range. Raise the temps higher to solar drying levels or kiln levels, and the RH can approach < 5%.

    Conversely, if you put anything wet in a steam room at 130 F, no drying will take place even though there is 130 F temp available. This is true because it is not temperature that determines drying rate, but partial pressure of H2O of the air, where the water goes when drying occurs.

    Generalizations about summer versus winter are always wrong, because as many people mentioned conditions vary from location to location, AND from year to year for a given location. Some winters around here can be 40s and rain for weeks. When it rains, its 100% RH. The last few days and next few days, we will have have excellently drying conditions even though the temps will be frigid because the air is soooo dry. Also, we should have sun during the short winter days and wind.

    Just because it does take heat to vaporize H20, does not mean that there is not heat available to be absorbed at -20 F air. There is plenty of heat available. It is the heat that comes from lowering the temps of the surroundings from -20 to -22. The driver is the dryness of the air, aka the partial pressure of H2O in the air.

    So drying occurs both summer and winter, driven by the partial pressure of H2O in the air. When RH reaches 100%, the air reaches its capacity for carrying any more water. Raise the temp of that air, RH goes down; lower the temp of 100% RH air and water will condense out on surfaces below the dew point. In my neck of the woods, we should get a lot of drying this week with frigid temps. But not enough to dry out freshly cut oak. As many have mentioned, bringing the wood inside, it dries even quicker, because at the higher temps in a house the RH is even lower (except for cooking, humidifiers, showers w/o exhausting air, etc. which all adds water to the air.). If you want to get into the science and engineering of drying, a study of psychrometrics can be found at:

    http://en.wikipedia.org/wiki/Psychrometrics

    The psychrometric chart is used by engineers for HVAC cals of the heat and water content of air at various points in a process.
  13. DBoon

    DBoon Minister of Fire

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    Agreed that there are too many variables to really draw any conclusions that would be valid for everyone. The advice I've seen often to keep it outside, covered, and in an exposed area with as much sun and wind as possible is going to dramatically speed up the seasoning and drying.
  14. Green Energy

    Green Energy Feeling the Heat

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    A dramatic example of how there is plenty of heat to evaporate water into very cold air is lake effect snow. I just checked out the Accuweather map of lake effect snow for the Great Lakes: 12 - 18" for the southern rim of Lake Erie. Dry air whipping across the lake drives the evaporation even when the air is frigid. It can always find the heat to evaporate water into the dry air by simply lowering the temps of surrounds even lower.
  15. raybonz

    raybonz Minister of Fire

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    Judging by all the hot air in this thread I would venture to say it would dry fastest in this thread than anywhere on earth!! LOL :ahhh:

    Ray
  16. CrawfordCentury

    CrawfordCentury New Member

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    Good concise explanation, IMO.

    And if you're wondering, laundry will dry at below freezing temps when hung on an outdoor line. It would take 2 to 3x as long.

    Same basic principle as to why the ice cubes in my freezer from the Halloween party are some 40% smaller than when I first made them.
  17. iceman

    iceman Minister of Fire

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    lmao!!

    after taking part of this wonderful debate... it seems as if the conclusions is a draw! to many variables and due to the fact that it can dry in winter and it can dry in summer....
    BUT one thing that just occured to me is my calendar was off...in my head winter starts by thanksgiving. around this time i am usually burning 24/7 no later than thanksgiving... so my arguement was based on in "my head" i get more/just as much seasoning from sept -dec than from june -august (when our temps are there hottest)... i wasnt thinking jan-feb-march vs june -july-august .... while i do believe my wood will still season, but prolly not as much as june-july-august.... now sept-early dec yes i do believe i get more than june -august in most years of course that is subject to change according to weather!... but this has been a great debate!!!
  18. raybonz

    raybonz Minister of Fire

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    So true and like all debates they are full of hot air! Though wood does dry in winter it does best when the air is warm as the air being warm is able to hold that much more moisture hence the higher humidity in the summer... The saturation point of air is much higher in hot temperatures than cool temperatures... Heat will enhance evaporation in most situations and also the ability to absorb the moisture that is given off as a result... Interesting subject for sure and lots of good well thought out answers all around... This is why I love this forum however when the air warms up I tend to evaporate and condense back here when the weather cools back off!


    Ray
  19. bbc557ci

    bbc557ci New Member

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    Typical central NY guy... how dare you introduce hard evidence into this debate LMAO :)

    btw.... Great discussion, very interesting!!
  20. dave11

    dave11 Minister of Fire

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    Exactly! That's what I tried to say with my last post, but maybe I didn't say it clearly enough.

    You folks who think there is no "right answer" to this are certainly wrong.There is a right answer, and it has nothing to do with your location. Just because some other folks keep stating conflicting opinions doesn't meant there's no right answer.

    Firewood has to dry faster in warmer temps than colder. If you take frozen wood, and lower the humidity around it to zero, it will not dry one bit until enough energy is absorbed from the environment to cause sublimation. Wood at 80 degrees F will dry faster than wood at 20 degrees F, no matter what the humidity is. At atmospheric pressure, which is a constant, high humidity will not impede water from leaving the wood, if there's enough energy to make it do so, and low humidity will not make it go any faster.

    It's easy to prove from every day experience. Imagine a pot of boiling water. Can you make it boil less just by covering it with a lid? You can, only if the lid is airtight and increases the pressure inside the pot. If you cover it with a loose lid, so that some steam gets out here and there, you will greatly increase the humidity over the water, but you will not make it boil any less, because it doesn't care how much water vapor is over its surface,. It only cares about the pressure, and the temperature applied.

    Same with firewood, which is exposed to a constant atmospheric pressure, but is slowly absorbing energy/heat from it's surroundings, and so, being heated, just like the water in a pot. Just much slower

    Look up the values of the enthalpy of vaporization and sublimation. They are dependent only upon the atmospheric pressure, not on the partial pressure of the substance in question. Since the atmospheric pressure around the wood is constant, it's mainly the temperature that affects the rate of water evaporation.

    Wood therefore must dry much faster in warmer temps. Everywhere on earth.

    This corresponds to published data in woodworking books.
  21. iceman

    iceman Minister of Fire

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    The problem was.. the op asked if it dried quicker in the winter or summer..... thats where the whole location etc... everything came in..... some of us have real humid summers very dry breezy falls thts wht started the whole thing...
    in another post someone said his wood dries out in his house in the winter time.. and someone else pointed out it was because its warm with no humidity .. which is true... but 65 -70 degrees with low humidity is what we get here sept -oct in july august we get hot but very humid... the weather alert to stay indoors the air is to thick.... so prime time for me inmy location is often fall-early winter not "summer" so to speak...
    but it was a great deabte and wood dries year round with different variables at least that did come out of it...
    cool temps will cause evaporation but that is to a certain point then you have the sublimation ... which is slower... so once we get steady below say 20 it really slows down... wheras if its dry in the summer no matter how high the temp goes you are still gonna have evaporation....
  22. leaddog

    leaddog Minister of Fire

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    It only cares about the pressure, and the temperature applied.

    Same with firewood, which is exposed to a constant atmospheric pressure, but is slowly absorbing energy/heat from it's surroundings, and so, being heated, just like the water in a pot. Just much slower

    Look up the values of the enthalpy of vaporization and sublimation. They are dependent only upon the atmospheric pressure, not on the partial pressure of the substance in question. Since the atmospheric pressure around the wood is constant, it's mainly the temperature that affects the rate of water evaporation.

    Wood therefore must dry much faster in warmer temps. Everywhere on earth.

    This corresponds to published data in woodworking books.[/quote]

    so does that mean that if I put my wood in a vaccum and add heat it will dry faster???????????????????
    leaddog
  23. Green Energy

    Green Energy Feeling the Heat

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    OK, I'm may be a sucker for bait, but here goes: I know it is counter intuitive, but heat is not nearly as important as the relative humidity. Heat appears to be the drying agent, but only when the heat lowers the RH. There is more heat on a 70 summer morning, than tonight (teens to 20s). Yet in many locations in the East, overnight and in the early summer morning, the RH approaches 100% during humid weather. If there is morning dew, then there is 100% RH at ground level. No drying is happening on nights/mornings. No drying is occurring when its raining, regardless of whether it's warm rain or cold rain. This is not because that the outside of the wood can get wet, because the air is saturated with water and there is no ability to hold more water.

    When there is 100% RH, the air can not hold any more water. No drying occurs because there is no place for the air to go.

    Put a dry towel in a 130 F steam room and the towel will become wet and never dry out because the RH is at 100% even though there is plenty of heat.

    The partial vapor pressure is not the same at the atmospheric pressure. High RH correspond to high partial H20 vapor pressure, low RH correspond to low partial H2O vapor pressure. Either condition occurs at sea level or at 10,000 ft above sea level. Dry air is literally sucking water into it where ever water is available to it.

    The prime mover of water coming out of wood, laundry, or you name it is low partial vapor pressure in the air adjacent to the surface. Warming the air, lowers the RH/partial pressure, that why it appears that heat causes the drying. But heat is just lowering the RH of the air. RH of the air is what matters.

    So if you want to generalize, more drying occurs during dry weather with low humidity, then during rainy weather and high humidity.

    Humidity is everything when it comes to drying.
  24. LLigetfa

    LLigetfa Minister of Fire

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    I haven't seen this much junk science before. Reminds me "Sanford and Son".

    http://www.fulmersbelly.com/img/sanford.jpg

    I can say my Winter dried wood actually absorbs moisture in the Summer. Not to worry though, it will dry out again come Winter.
  25. Green Energy

    Green Energy Feeling the Heat

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    Great pic! Way to bring the comic relief. What does "GSD" in your signature stand for?
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