# the kiln dried versus air dried debate!



## jimmyjames

Looking around the old inter web and there's always the air dried versus kiln dried debate..... I keep hearing that air dried lumber moves more than kiln dried, does kiln dried lumber really move more than air dried? Does lumber really care how it was dried? Does it develop a memory? The only difference I have ever seen with the 2 is that kiln dried of course is faster drying but I think kiln dried moves more, especially fresh kiln dried wood at 6 or 7 percent moisture since it has to equalize . All my lumber that I have ever checked was between 10 and 12% that has sat in the shop for any period of time, I always hear.... 12% is way too wet to work with.... bla bla bla....... and then there's people saying you must equalize your wood to your shop or where the furniture will live, how is that even possible? I can see maybe if your building it for your home but then its still going to move anyway unless your home is humidity controlled with humidifier/dehumidifiers, my house humidity swings a 40% difference from summer to winter.......... I'm sorry this is just a rant basically..... there's so many closet wood geniuses giving out poor advice all over the net about this topic..... I am not an expert on the topic but qeeze a lot of it is common sense! I mean come on 12% moisture wood is 12% moisute wood.... it doesn't care if it was kiln dried or not unless you fried the cell walls from cooking it too fast in a kiln, its all going to move with humidity changes no matter what!


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## barry richardson

Good question, one that I have wondered about as well. Roy Underhill from the woodwright's Shop says that air dried wood is more workable with hand tool and bends better, he didn't say anything that I recall about stability or movement though...


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## Kevin

Damn Jim you're supposed to be responsible for keep order not stirring the pot!



Jk of course - it's how we learn and we're never too old or knowledgeable to learn .....


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## Mike1950

I have to agree with Kevin- quite a pot to stir. I can see how there would be very many answers for this. Air dried wood in Texas vs Iowa vs Arizona vs Eastern Washington would have to be different. Personally I think all that have answered thread so far live in diversified enough climates to have much different answers to ? but still be right for their climate. My air dried wood at summer end outside is 7-8% inside shop it will be 12% at the same time. Check same wood in Jan and the reading will be just the opposite. 
All this said commercially kiln dried walnut seems washed out -air dried more vibrant-with more color. This is by no means scientific-just my observation. When I do a bug kill on air dried it changes nothing as far as color.
Also we have been building furniture with air dried wood for a long time. Seems like combo of both gets the best of both worlds.


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## jimmyjames

Kevin said:


> Damn Jim you're supposed to be responsible for keep order not stirring the pot!
> 
> 
> 
> Jk of course - it's how we learn and we're never too old or knowledgeable to learn .....



I would just like a debate about the subject with actual facts, i can see air dried lumber being more workable like mentioned above, as heat from the higher commercial kilns can cause it to be more brittle, the steam bending folk know alot about that given subject. I like to learn new things everyday, and if im really interested in the subject i want to know every thing imaginable about it. I like being the best at what i do and any added knowledge gets me closer to that goal. 

For those of you that have done allot of flat work that have worked with both air and kiln dried, whats your observations on the differences of the 2?

If you have 2 boards both the exact same size rough sawn, 1 kiln dried and 1 air dried, both flat sawn with similar grain pattern and both staballized to roughly 10-12%, after surfacing the wood flat and square does one or the other really want to move more? Does kiln drying change the characteristics of the cells/structure/ability to absorb moisture? I can see maybe the commercial kilns with they're aggressive kiln schedules might do something to the wood but what? I do know kilns can do things to the wood if done incorrectly, ive seen pictures of over 400,000 feet of walnut being ground in a tub grinder to be burnt since the temp controller in a steam box malfunctioned and collapsed the cell walls of the wood making it worthless...... but that was from over 190 degree temps in the steam box and no steam was being introduced into the box so it was dry heat on fresh green wood....


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## Mike1950

jimmyjames said:


> Kevin said:
> 
> 
> 
> Damn Jim you're supposed to be responsible for keep order not stirring the pot!
> 
> 
> 
> Jk of course - it's how we learn and we're never too old or knowledgeable to learn .....
> 
> 
> 
> 
> I would just like a debate about the subject with actual facts, i can see air dried lumber being more workable like mentioned above, as heat from the higher commercial kilns can cause it to be more brittle, the steam bending folk know alot about that given subject. I like to learn new things everyday, and if im really interested in the subject i want to know every thing imaginable about it. I like being the best at what i do and any added knowledge gets me closer to that goal.
> 
> For those of you that have done allot of flat work that have worked with both air and kiln dried, whats your observations on the differences of the 2?
> 
> If you have 2 boards both the exact same size rough sawn, 1 kiln dried and 1 air dried, both flat sawn with similar grain pattern and both staballized to roughly 10-12%, after surfacing the wood flat and square does one or the other really want to move more? Does kiln drying change the characteristics of the cells/structure/ability to absorb moisture? I can see maybe the commercial kilns with they're aggressive kiln schedules might do something to the wood but what? I do know kilns can do things to the wood if done incorrectly, ive seen pictures of over 400,000 feet of walnut being ground in a tub grinder to be burnt since the temp controller in a steam box malfunctioned and collapsed the cell walls of the wood making it worthless...... but that was from over 190 degree temps in the steam box and no steam was being introduced into the box so it was dry heat on fresh green wood....
Click to expand...


Jimmy, To add to my above statement. I can tell the difference between commercially kiln (steam) dried walnut and air dried in color only. I think the KD looks washed out-very mono colored. As far as work ability I am by no means good enough to tell the difference. PS. I mostly work only air dried because of the color.


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## woodtickgreg

It has to be kiln dried or it's not good wood.....BS! Think about this, all the furniture that was hand made 100 years or more ago and was all air dried and is still here today. they didn't have kilns then to speed things up. I have used both, but pretty much use air dried wood now as I mill my own and air dry it in my garage....slowly. It does seem to have better color as Mike stated, it does seem to be more workable with tools and not as splintery. Now about movement, all wood is going to move with seasonal changes in humidity, period! Humidity here in Michigan varies a great deal, bone dry in the winter to 98% + in the summer. I have never had any of my air dried lumber projects fail after completion, you have to allow for wood movement when you are building things. I really don't get all worked up about boards that split when they are drying either, let em, and then cut around the defects and use the stable wood. You have no idea what kind of internal stress is in a board when you mill it, but it will reveal itself when drying. Letting wood acclimate in your shop....my shop is in the basement....yes it is important imo, I have seen wood left on my bench move and warp just a couple of days after final milling. Now I let it acclimate for a week or so stickered, mill it close to dimension, acclimate again for a few days, then final mill. Remember I am in a wild humidity swing region. 
This is all my experience and observations and just my opinion for what it's worth. Kiln dried is better than air dried? I aint buying it, it is faster though and can be more controlled, that's just better for the mills that sell it and have to be efficient. I think this whole debate was started by the sawmill and kiln manufacturers to sell kilns.  LOL 
I personally prefer air dried wood for my projects.......and my wallet.


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## sbwertz

I have a mini-kiln dryer in my backyard. I have an old gas bbq grill with a thermometer in the lid. Sitting in the AZ sun, it regular hits 150 degrees or more. My dehydrator tops out at 145 degrees. Most of the time, I just let the ambient 100 degree plus air with 7 percent humidity do the job, but I can quick dry in the bbq or dehydrator if I have to. (I have a separate big dehydrator for the shop. It made the blueberries taste funny.)


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## Kevin

Jim, air drying is the same everywhere on the planet pretty much. About the only thing that will vary is the time it takes and the EMC. As long as you properly sticker, stack, and cover, and have the proper airflow, you can't hardly hurt it. Some species that move a lot will give you more waste than others no matter what you do. You can minimize the defects of some species by kiln drying it first, and vise versa. 

There is a lot of empirical data (I'm not referring to opinions) available on the topic so don't make it complex - because it isn't. Download and READ the link below - IMO it's the best source for information available for air drying and kiln drying wood - it'll enable you from to recognize fact from fiction from fluff. Read as you have the time and keep as a reference and you'll be way ahead of the game. Add to it some years of actual drying experience and viola - you're a drying wizard. Seriously, air drying is a very simple undertaking if you follow the simple rudiments given in the pdf below. 

Here's the link.


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## woodtickgreg

Kevin said:


> Add to it some years of actual drying experience and viola - you're a drying wizard. Seriously, air drying is a very simple undertaking .........



+1 It really isn't rocket science.


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## Kevin

woodtickgreg said:


> ...all the furniture that was hand made 100 years or more ago and was all air dried and is still here today.



Greg, the "old furniture" was made with old growth timber. It makes a huge difference. If you build with new growth (wide rings etc.) lumber and simply air dry it to say 12% EMC, then it sees 6% MC inside during a winter it's pretty much got no choice but to have problems eventually. I built a blanket chest using brown ash and walnut in the early 90s that didn't wreck until the past several years. It was kiln dried wood but I had allowed it to acclimate to EMC before building with it. It may take years depending on construction and joinery but joints commonly fail because of this. 



woodtickgreg said:


> they didn't have kilns then to speed things up. ....



Yes they did.


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## woodtickgreg

Kevin said:


> woodtickgreg said:
> 
> 
> 
> ...all the furniture that was hand made 100 years or more ago and was all air dried and is still here today.
> 
> 
> 
> 
> Greg, the "old furniture" was made with old growth timber. It makes a huge difference. If you build with new growth (wide rings etc.) lumber and simply air dry it to say 12% EMC, then it sees 6% MC inside during a winter it's pretty much got no choice but to have problems eventually. I built a blanket chest using brown ash and walnut in the early 90s that didn't wreck until the past several years. It was kiln dried wood but I had allowed it to acclimate to EMC before building with it. It may take years depending on construction and joinery but joints commonly fail because of this.
> 
> 
> 
> woodtickgreg said:
> 
> 
> 
> they didn't have kilns then to speed things up. ....
> 
> Click to expand...
> 
> 
> Yes they did.
Click to expand...

All good points, I'm just sayin that everything does not have to be kiln dried, based on experience.
And ok maybe they had kilns, :dunno: but not as many and not as widely used, I'm sure that tons of furniture was made with a d lumber. The only point that I was poorly trying to make is that a d is a viable source of wood for projects. The wood I use is all a d and not old growth and my projects will still be around after I am gone. There will be some that only use kiln dried and some like me that prefer a d lumber. I'm all about low buck and it works for me. I'm just sayin don't be afraid to use a d as an option. it is ok and stable if stored properly like kiln dried. I know of other wood workers here in Michigan that a d their lumber too, and even with the humidity swings it still works. Some gun stock makers will only us a d for their stocks. I'm not saying only use a d lumber or only use kiln dried lumber, just be open minded and understand that both are good and will work. Based on my experience and not science.  For me it's not about finding or using the perfect lumber, it's about processing and using a beautiful natural resource with all it's flaws and quirks. If I wanted perfect sterile lumber I could go to menards where each board doesn't have a single knot or flaw and is individually shrink wrapped......or I could mill my own found logs a d it and have some fun in my shop doing my hobby on the cheap.


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## Mike Jones

Debating this issue is most often prevalent amongst the "shade tree", or hobby level woodworker. This, because once you get to the commercial level, economics, ('the market') will determine what _method _ to use to dry. And what method of drying works best for your end-use product. As a lumber producer, you will, of necessity, produce dimensional timber that is consistent in the qualities desired by your buyers and potential buyers.

The capital costs for air drying facilities may not be as cheap as the costs for set-up of a dry kiln. On a commercial level, for air drying, you may need some acreage that is all level and accessible to fork lift travel during winter as well as summer climates. A shed, or roof port may be required. Young, strong bodies for stacking and stickering....

It is not really a debate, (It's not a cut and dried issue :teethlaugh:), because it....well, it depends....and if you are going beyond the 'hobby level' it's most important to know the market in advance.

Geeze, I hope some of these thoughts can be helpful to you. Moisture content and species is critical to much of my work as a woodturner, but whether it came to 15% by way of kiln or not is seldom an issue.


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## woodtickgreg

Mike Jones said:


> Debating this issue is most often prevalent amongst the "shade tree", or hobby level woodworker. This, because once you get to the commercial level, economics, ('the market') will determine what _method _ to use to dry. And what method of drying works best for your end-use product. As a lumber producer, you will, of necessity, produce dimensional timber that is consistent in the qualities desired by your buyers and potential buyers.
> 
> The capital costs for air drying facilities may not be as cheap as the costs for set-up of a dry kiln. On a commercial level, for air drying, you may need some acreage that is all level and accessible to fork lift travel during winter as well as summer climates. A shed, or roof port may be required. Young, strong bodies for stacking and stickering....
> 
> It is not really a debate, (It's not a cut and dried issue :teethlaugh:), because it....well, it depends....and if you are going beyond the 'hobby level' it's most important to know the market in advance.
> 
> Geeze, I hope some of these thoughts can be helpful to you. Moisture content and species is critical to much of my work as a woodturner, but whether it came to 15% by way of kiln or not is seldom an issue.


Excellent points from a professional and sawyers view. Me being a lowly hobbyist I never considered all those points, and they all make sense. :hatsoff: This is a debate that I always enjoy, it has come up before and it always gives me things to think about. It's all good stuff


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## sprucegum

I think it makes a difference where you live. Here in the NE it is almost impossible to air dry wood below 12 or 14 percent. If you make a piece from 12 percent wood and bring it into the house in the winter it will move a bunch. Temps in the winter drop below zero, air this cold is always very dry air the house will be heated to 70 give or take a little so the air inside our houses in the winter is dryer than any desert. If you live in Arizona air dry may work for you. Where I live it will not. I often bring air dried wood into my basement in the winter and put it in a rack near my wood fired boiler for 2 or three weeks before using it for a project. Believe me it moves, twists, cracks, and cups but I figure when it is done dancing around it is safe to use. I suppose when I do this I am for all practical purposes KDing it.


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## jimmyjames

sprucegum said:


> I think it makes a difference where you live. Here in the NE it is almost impossible to air dry wood below 12 or 14 percent. If you make a piece from 12 percent wood and bring it into the house in the winter it will move a bunch. Temps in the winter drop below zero, air this cold is always very dry air the house will be heated to 70 give or take a little so the air inside our houses in the winter is dryer than any desert. If you live in Arizona air dry may work for you. Where I live it will not. I often bring air dried wood into my basement in the winter and put it in a rack near my wood fired boiler for 2 or three weeks before using it for a project. Believe me it moves, twists, cracks, and cups but I figure when it is done dancing around it is safe to use. I suppose when I do this I am for all practical purposes KDing it.



But what do I do when my humidity in my house swings from below 10% in the winter to close to 50% in the hot humid days of summer? I think its probably more important too build your piece with expansion and movement figured into the design. I think it doesn't matter if a piece of wood is kiln dried or air dried, both will still reach the same exact moisture content in the wood, its not like kiln dried lumber stays at 6% . 

I think this discussion has a lot of personal preference. It goes along with another discussion I would like to have someday about how long it takes to air dry lumber, many believe a year per inch of thickness but I have some 8/4 walnut that was cut 4 months ago and is at 11% right now, but then again it is in a metal building that probably reaches 120+ degrees in the daytime as well.....


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## Mike1950

jimmyjames said:


> sprucegum said:
> 
> 
> 
> I think it makes a difference where you live. Here in the NE it is almost impossible to air dry wood below 12 or 14 percent. If you make a piece from 12 percent wood and bring it into the house in the winter it will move a bunch. Temps in the winter drop below zero, air this cold is always very dry air the house will be heated to 70 give or take a little so the air inside our houses in the winter is dryer than any desert. If you live in Arizona air dry may work for you. Where I live it will not. I often bring air dried wood into my basement in the winter and put it in a rack near my wood fired boiler for 2 or three weeks before using it for a project. Believe me it moves, twists, cracks, and cups but I figure when it is done dancing around it is safe to use. I suppose when I do this I am for all practical purposes KDing it.
> 
> 
> 
> 
> But what do I do when my humidity in my house swings from below 10% in the winter to close to 50% in the hot humid days of summer? I think its probably more important too build your piece with expansion and movement figured into the design. I think it doesn't matter if a piece of wood is kiln dried or air dried, both will still reach the same exact moisture content in the wood, its not like kiln dried lumber stays at 6% .
> 
> I think this discussion has a lot of personal preference. It goes along with another discussion I would like to have someday about how long it takes to air dry lumber, many believe a year per inch of thickness but I have some 8/4 walnut that was cut 4 months ago and is at 11% right now, but then again it is in a metal building that probably reaches 120+ degrees in the daytime as well.....
Click to expand...


UH OH- You have done it now- you said 1" per year- when the crazy Irishman sees that whewweeee!!!!:dash2::dash2:
Have you cut the walnut and checked the center??? 
No way any one standard works. Here very low humidity and 80-100 somewhere else same temps-90% humidity. Different woods dry different. I do not think there is a one size fits all-not even a guess............ Just an opinion though.


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## woodtickgreg

Mike1950 said:


> jimmyjames said:
> 
> 
> 
> 
> 
> sprucegum said:
> 
> 
> 
> I think it makes a difference where you live. Here in the NE it is almost impossible to air dry wood below 12 or 14 percent. If you make a piece from 12 percent wood and bring it into the house in the winter it will move a bunch. Temps in the winter drop below zero, air this cold is always very dry air the house will be heated to 70 give or take a little so the air inside our houses in the winter is dryer than any desert. If you live in Arizona air dry may work for you. Where I live it will not. I often bring air dried wood into my basement in the winter and put it in a rack near my wood fired boiler for 2 or three weeks before using it for a project. Believe me it moves, twists, cracks, and cups but I figure when it is done dancing around it is safe to use. I suppose when I do this I am for all practical purposes KDing it.
> 
> 
> 
> 
> But what do I do when my humidity in my house swings from below 10% in the winter to close to 50% in the hot humid days of summer? I think its probably more important too build your piece with expansion and movement figured into the design. I think it doesn't matter if a piece of wood is kiln dried or air dried, both will still reach the same exact moisture content in the wood, its not like kiln dried lumber stays at 6% .
> 
> I think this discussion has a lot of personal preference. It goes along with another discussion I would like to have someday about how long it takes to air dry lumber, many believe a year per inch of thickness but I have some 8/4 walnut that was cut 4 months ago and is at 11% right now, but then again it is in a metal building that probably reaches 120+ degrees in the daytime as well.....
> 
> Click to expand...
> 
> 
> UH OH- You have done it now- you said 1" per year- when the crazy Irishman sees that whewweeee!!!!:dash2::dash2:
> Have you cut the walnut and checked the center???
> No way any one standard works. Here very low humidity and 80-100 somewhere else same temps-90% humidity. Different woods dry different. I do not think there is a one size fits all-not even a guess............ Just an opinion though.
Click to expand...

Just so the irishman understands it's 1 year per inch of thickness :hornets:


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## Mike1950

woodtickgreg said:


> Mike1950 said:
> 
> 
> 
> 
> 
> jimmyjames said:
> 
> 
> 
> 
> 
> sprucegum said:
> 
> 
> 
> I think it makes a difference where you live. Here in the NE it is almost impossible to air dry wood below 12 or 14 percent. If you make a piece from 12 percent wood and bring it into the house in the winter it will move a bunch. Temps in the winter drop below zero, air this cold is always very dry air the house will be heated to 70 give or take a little so the air inside our houses in the winter is dryer than any desert. If you live in Arizona air dry may work for you. Where I live it will not. I often bring air dried wood into my basement in the winter and put it in a rack near my wood fired boiler for 2 or three weeks before using it for a project. Believe me it moves, twists, cracks, and cups but I figure when it is done dancing around it is safe to use. I suppose when I do this I am for all practical purposes KDing it.
> 
> 
> 
> 
> But what do I do when my humidity in my house swings from below 10% in the winter to close to 50% in the hot humid days of summer? I think its probably more important too build your piece with expansion and movement figured into the design. I think it doesn't matter if a piece of wood is kiln dried or air dried, both will still reach the same exact moisture content in the wood, its not like kiln dried lumber stays at 6% .
> 
> I think this discussion has a lot of personal preference. It goes along with another discussion I would like to have someday about how long it takes to air dry lumber, many believe a year per inch of thickness but I have some 8/4 walnut that was cut 4 months ago and is at 11% right now, but then again it is in a metal building that probably reaches 120+ degrees in the daytime as well.....
> 
> Click to expand...
> 
> 
> UH OH- You have done it now- you said 1" per year- when the crazy Irishman sees that whewweeee!!!!:dash2::dash2:
> Have you cut the walnut and checked the center???
> No way any one standard works. Here very low humidity and 80-100 somewhere else same temps-90% humidity. Different woods dry different. I do not think there is a one size fits all-not even a guess............ Just an opinion though.
> 
> Click to expand...
> 
> Just so the irishman understands it's 1 year per inch of thickness :hornets:
Click to expand...


Yes that is the way I heard it also 1 INCH PER YEAR. :rotflmao3::rotflmao3::rotflmao3::rotflmao3:


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## Kevin

Are we talking about an imperial, Scottish, international, or a barleycorn inch? And is it per Gregorian, Julian, Draconic, Lunar, Gaussian or seasonal year? And if a seasonal year, is that where the term to "season" wood comes from? And if you don't cover your stack of lumber, will your wood have joy, will it have fun, will it have seasons in the sun? These are a few things I want to know. 

:question:


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## jimmyjames

Mike1950 said:


> jimmyjames said:
> 
> 
> 
> 
> 
> sprucegum said:
> 
> 
> 
> I think it makes a difference where you live. Here in the NE it is almost impossible to air dry wood below 12 or 14 percent. If you make a piece from 12 percent wood and bring it into the house in the winter it will move a bunch. Temps in the winter drop below zero, air this cold is always very dry air the house will be heated to 70 give or take a little so the air inside our houses in the winter is dryer than any desert. If you live in Arizona air dry may work for you. Where I live it will not. I often bring air dried wood into my basement in the winter and put it in a rack near my wood fired boiler for 2 or three weeks before using it for a project. Believe me it moves, twists, cracks, and cups but I figure when it is done dancing around it is safe to use. I suppose when I do this I am for all practical purposes KDing it.
> 
> 
> 
> 
> But what do I do when my humidity in my house swings from below 10% in the winter to close to 50% in the hot humid days of summer? I think its probably more important too build your piece with expansion and movement figured into the design. I think it doesn't matter if a piece of wood is kiln dried or air dried, both will still reach the same exact moisture content in the wood, its not like kiln dried lumber stays at 6% .
> 
> I think this discussion has a lot of personal preference. It goes along with another discussion I would like to have someday about how long it takes to air dry lumber, many believe a year per inch of thickness but I have some 8/4 walnut that was cut 4 months ago and is at 11% right now, but then again it is in a metal building that probably reaches 120+ degrees in the daytime as well.....
> 
> Click to expand...
> 
> 
> UH OH- You have done it now- you said 1" per year- when the crazy Irishman sees that whewweeee!!!!:dash2::dash2:
> Have you cut the walnut and checked the center???
> No way any one standard works. Here very low humidity and 80-100 somewhere else same temps-90% humidity. Different woods dry different. I do not think there is a one size fits all-not even a guess............ Just an opinion though.
Click to expand...


Yep, I sold a 4' piece cut off a 10' slab for a park style bench, I checked the end grain right after cutting it with the skilsaw, I was surprised that it was so dry


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## woodtickgreg

Kevin said:


> will your wood have joy, will it have fun, will it have seasons in the sun? These are a few things I want to know.
> 
> :question:


Answer: YES


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## davidgiul

Here on the wet side of Kauai, air dried wood will never reach 15% EMC. The best you can expect is 30%. So if you want 12% you have to KD. The thing about AD is that it takes forever whereas KD can be accomplished in a much shorter time span. I would say that Dave Martin of GVWP would have a view on this topic


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## Kevin

davidgiul said:


> ... I would say that Dave Martin of GVWP would have a view on this topic



Everyone has a view on it, but our views don't change physics. There are immutable laws concerning the drying of wood that opinions and perceptions cannot change. Most members are saying the same basic thing the others are, and most of it is correct. A few statements belong on Pluto.


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## Mike1950

davidgiul said:


> Here on the wet side of Kauai, air dried wood will never reach 15% EMC. The best you can expect is 30%. So if you want 12% you have to KD. The thing about AD is that it takes forever whereas KD can be accomplished in a much shorter time span. I would say that Dave Martin of GVWP would have a view on this topic



David- question for you- So you build at 10%?? with your kind of climate- what % of moisture is finished product 1 year later. Always having lived and built in a semi arid climate, I have no clue as to the answer to above. also how do you keep bugs out of such wet wood?


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## AustinTom

I just skimmed all the posts and hope this doesn't repeat something. Most of my wood comes from a lumber yard. It is probably all KD but it may sit in the lumber yard for months or years before sale. The lumber yard is wide open to the outside and no matter what the MC was after leaving the kiln, when I buy it, it is most likely at the same MC as if I had air dried it. I can't see that there is tangible difference; MC=MC. Steaming walnut is a different conversation. That is done to spread out the heartwood colors so more of the sapwood is useable. I agree that it creates boring wood but it really isn't a KD issue.


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## jimmyjames

AustinTom said:


> I just skimmed all the posts and hope this doesn't repeat something. Most of my wood comes from a lumber yard. It is probably all KD but it may sit in the lumber yard for months or years before sale. The lumber yard is wide open to the outside and no matter what the MC was after leaving the kiln, when I buy it, it is most likely at the same MC as if I had air dried it. I can't see that there is tangible difference; MC=MC. Steaming walnut is a different conversation. That is done to spread out the heartwood colors so more of the sapwood is useable. I agree that it creates boring wood but it really isn't a KD issue.



Excellent post, that's the info I was looking for, if there's any noticeable difference in the wood and that mc is Mc


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## sprucegum

I asked some of the same questions asked here when I picked up some wood at the kiln last week. The kiln operator said that when you kiln dry wood you are collapsing the cells in the wood somewhat and that it is almost impossible to make kd wood take on as much moisture as it once had. He did concede however that over time the moisture level will crawl back up somewhat. When I build a piece of furniture I get the wood as dry as possible and seal all surfaces of the piece top, bottom, inside & and outside in an effort to stabilize the moisture content. I have had pretty good luck doing it this way. 
Just as a point of interest there was a local family well know for the chairs they made in the 1800's and early 1900's. They turned the legs from green wood and the stretchers and rounds from dry wood. the holes made in the legs shrunk as the wood dried and locked the rounds in place. There are many of these chairs still in use.


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## Mike1950

sprucegum said:


> I asked some of the same questions asked here when I picked up some wood at the kiln last week. They kiln operator said that when you kiln dry wood you are collapsing the cells in the wood somewhat and that it is almost impossible to make kd wood take on as much moisture as it once had. He did concede however that over time the moisture level will crawl back up somewhat. When I build a piece of furniture I get the wood as dry as possible and seal all surfaces of the piece top, bottom, inside & and outside in an effort to stabilize the moisture content. I have had pretty good luck doing it this way.
> Just as a point of interest there was a local family well know for the chairs they made in the 1800's and early 1900's. They turned the legs from green wood and the stretchers and rounds from dry wood. the holes made in the legs shrunk as the wood dried and locked the rounds in place. There are many of these chairs still in use.



I have read the same about KD wood. I think steam benders prefer Green wood also.


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## Kevin

I don't know if this will answer anyone's questions, but there are some things that apply to wood movement, and wood drying, no matter where you live. 

When drying wood, you should plan your target MC to within 2 to 3% of its expected EMC. While in the case of wide seasonal swings which you cannot control (like sprucegum has), remember that while the wood moves, all of the wood is moving not just one part. Things like a breadboard top where grain orientation is perpendicular can really show the amount of movement, but the breadboard design is specifically designed to cope with it. Wood movement cannot be eliminated, you just have to build using joinery that is proven to be able to accommodate the movement. 

The only reason wood moves is because its MC changes. We know this for certain. Temperature has almost nothing to do with it and location has absolutley positively nothing to do with it other than the RH which dictates the MC in the wood. Wood movement due to fluctuations in temperature is so negligible so as not be measurable by a craftsman or hobbyist so it doesn't need to be considered when building with wood. 

Once wood has achieved EMC, most species will move 1% across the grain for every 4% of change in MC. Some species like oak will move more, others like mesquite will move less, but the majority of species will fit within this 1% for every 4% rule or very close to it no matter where you live. 

It's true that it doesn't matter whether wood got to 12% by AD or KD because 12% is 12% no matter what. I don't think anyone here has argued that or even thinks it's worthy of debate. The two main reasons wood is dried in a kiln is to A) kill bugs and B) increase the profit margin for wood processors. 

The worst kind of situation for wood items is when the MC changes rapidly. That's when you'll see the worst kind of damage to areas especially where grain orientation is opposite. Slow changes in MC (which translates to slower movement) allow the wood to release the tension as it moves and not let it get pent up before it can release it. Like tectonic plates, the slow movement cause tremors that aren't usually felt, but a rapid release of tension causes massive damage. Same with wood movement in a sense.

This may or may not answer any questions and I don't have all of them anyway. However I am fairly confident about what I have said.


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## jimmyjames

Well said Kevin, the one point I was trying to get across was that there isn't a difference in kiln dried versus air dried lumber once it really emc


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## Mike1950

jimmyjames said:


> Well said Kevin, the one point I was trying to get across was that there isn't a difference in kiln dried versus air dried lumber once it really emc



 Try to convince one of the stockmakers of that when you are trying to sell them on kiln dried.


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## Treecycle Hardwoods

Kevin said:


> davidgiul said:
> 
> 
> 
> ... I would say that Dave Martin of GVWP would have a view on this topic
> 
> 
> 
> 
> Everyone has a view on it, but our views don't change physics. There are immutable laws concerning the drying of wood that opinions and perceptions cannot change. Most members are saying the same basic thing the others are, and most of it is correct. A few statements belong on Pluto.
Click to expand...


I agree with Kevin that the opinion of woodworkers do not change physics... that being said if you are in the lumber biz and expect to have a reasonable rate of success on a small production sawmill you should be prepared to serve both sides of the opinion scale. I have customers who prefer one or the other. In some cases I have guys who use both depending on what their current project is. 

I learned the hard way the pit falls of air drying... being in the upper Midwest we can easily have temp swings of 30-40 degrees between night & day and from day to day. I can't stress enough that the sun is the enemy of an air drying operation leave your wood in the sun and watch it degrade. (this was my biggest mistake) RH of the air is a big factor with some species. Two winters ago I was half way thru milling a red oak when it got dark so I left the cant on the mill thinking that "its winter I'm good" when I finally got back to it a few weeks later the cant was checked bad. Lesson learned--- get oak into a controlled environment asap after milling to prevent it from drying to fast!! I am going thru some growing pains as my mill grows I will be retooling how I air dry in the future to include "sun screen" if you will. I plan on making smaller drying stations that have limited openings to the east and west, no southern exposure and completely open to the north. My goal is to slow down drying of air dried lumber in the first couple weeks to prevent degrade. In general the denser the wood the slower it should be dried in the beginning. This can't be controlled when using the air drying method like it can be when kiln drying.

Kiln drying has its pitfalls too. Case hardening and other cell hardening can change the physical properties of the wood when kiln drying is used. Honey comb checking (internal checking of lumber) is pretty much only found in kiln dried wood.

Bottom line is wood is alive and will be til it rots back to dust. It will take on what ever MC nature provides it with regardless of the method of drying. 

It was mentioned in the thread somewhere about furniture built in the 1700&1800's being mostly build with air dried lumber. When asking the average woodworker what is the most notable period of furniture building is in our country, the answer I receive most is the 1700's. I then ask about kilns from that period... while we here on woodbarter have a higher knowledge of woodworking history the average woodworker does not and it gets them thinking about the quality of air dried wood it that is the majority of what was used in the most memorable period of woodworking in our countries history.


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## Kevin

jimmyjames said:


> ...there isn't a difference in kiln dried versus air dried lumber once it really emc



Except for the bugs. 



Mike1950 said:


> Try to convince one of the stockmakers of that when you are trying to sell them on kiln dried.



That's a fact, and don't forget the luthiers who are even pickier than the gun stock guys if that is possible.


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## Mike1950

Kevin said:


> jimmyjames said:
> 
> 
> 
> ...there isn't a difference in kiln dried versus air dried lumber once it really emc
> 
> 
> 
> 
> Except for the bugs.
> 
> 
> 
> Mike1950 said:
> 
> 
> 
> Try to convince one of the stockmakers of that when you are trying to sell them on kiln dried.
> 
> Click to expand...
> 
> 
> That's a fact, and don't forget the luthiers who are even pickier than the gun stock guys if that is possible.
Click to expand...


I left them out -but not by accident. They are a whole 'nother breed. Probably for reasons though that are valid.


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## Kevin

Mike1950 said:


> Kevin said:
> 
> 
> 
> 
> 
> jimmyjames said:
> 
> 
> 
> ...there isn't a difference in kiln dried versus air dried lumber once it really emc
> 
> 
> 
> 
> Except for the bugs.
> 
> 
> 
> Mike1950 said:
> 
> 
> 
> Try to convince one of the stockmakers of that when you are trying to sell them on kiln dried.
> 
> Click to expand...
> 
> 
> That's a fact, and don't forget the luthiers who are even pickier than the gun stock guys if that is possible.
> 
> Click to expand...
> 
> 
> I left them out -but not by accident. They are a whole 'nother breed. Probably for reasons though that are valid.
Click to expand...


I agree. Hard to argue with centuries of artisan builders some of whom were off the chart geniuses.


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## Mike1950

Kevin said:


> Mike1950 said:
> 
> 
> 
> 
> 
> Kevin said:
> 
> 
> 
> 
> 
> jimmyjames said:
> 
> 
> 
> ...there isn't a difference in kiln dried versus air dried lumber once it really emc
> 
> 
> 
> 
> Except for the bugs.
> 
> 
> 
> Mike1950 said:
> 
> 
> 
> Try to convince one of the stockmakers of that when you are trying to sell them on kiln dried.
> 
> Click to expand...
> 
> 
> That's a fact, and don't forget the luthiers who are even pickier than the gun stock guys if that is possible.
> 
> Click to expand...
> 
> 
> I left them out -but not by accident. They are a whole 'nother breed. Probably for reasons though that are valid.
> 
> Click to expand...
> 
> 
> I agree. Hard to argue with centuries of artisan builders some of whom were off the chart geniuses.
Click to expand...


 DAMNNNN We agree -where the hell is my calendar!!!! :rotflmao3::rotflmao3:


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## Treecycle Hardwoods

Strativarius??? Not sure if he used kilns?


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## Kevin

Treecycle Hardwoods said:


> Strativarius??? Not sure if he used kilns?



I wasn't gonna ask you but you keep bringing it up . . . are you under the impression that building with air dried wood today, is the same as it was in before the late 19th century? If so that's not the case. I think some people see "old growth" and don't realize just how different the properties of it are compared to the stuff we have to work with today. All the strads, all the victorian and any other period furniture ever built back then was built using old growth timber. And they obviously had ways of getting it to the MC they needed whether it was simply air drying or in the attics of their churches or homes, they knew what they needed to do and how to do it. 

One thing is certain, old growth wood is much more stable than what we have today. I have never found a good history of wood drying - I think it's one of those subjects so arcane no one has ever been able to afford to invest the time to spend years researching it. The one or two books/publications of the history of commercial kilns in north america was deemed worthy because it's a huge industry and commercial kiln operation is huge, so the history of it is something the industry would want yo teach operators during training and a publisher could viably support that.

Ceramic kilns have been around for thousands of years. I find it difficult to believe that just because we don't have a book telling us about wood kiln history, or the history of wood drying which is a broader subject but along the same line, that wood kilns never existed before the point in history of what we are aware. So just because we cannot prove it one way or another - I find it impossible to believe that air drying has been the only method of removing moisture from wood until the latter part of the 19th century. 

If there's a work on the history of wood kilns, or a decent treatise on the of wood drying in general throughout history and you're aware of it please let us know. I don't know of one. 

A note about Stradivarius: He was one of the geniuses I was referring to and his methods are still not completely known. Analysis of some of the wood he used shows salt crystals, gold, cyanide etc. so he used any number of methods still mostly unknown to dry/stabilize/preserve/fumigate his wood so he probably isn't a good benchmark for a general statement about wood drying techniques - he lived on his own planet.


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## Treecycle Hardwoods

Kevin said:


> Treecycle Hardwoods said:
> 
> 
> 
> Strativarius??? Not sure if he used kilns?
> 
> 
> 
> 
> I wasn't gonna ask you but you keep bringing it up . . . are you under the impression that building with air dried wood today, is the same as it was in before the late 19th century? If so that's not the case. I think some people see "old growth" and don't realize just how different the properties of it are compared to the stuff we have to work with today. All the strads, all the victorian and any other period furniture ever built back then was built using old growth timber. And they obviously had ways of getting it to the MC they needed whether it was simply air drying or in the attics of their churches or homes, they knew what they needed to do and how to do it.
> 
> One thing is certain, old growth wood is much more stable than what we have today. I have never found a good history of wood drying - I think it's one of those subjects so arcane no one has ever been able to afford to invest the time to spend years researching it. The one or two books/publications of the history of commercial kilns in north america was deemed worthy because it's a huge industry and commercial kiln operation is huge, so the history of it is something the industry would want yo teach operators during training and a publisher could viably support that.
> 
> Ceramic kilns have been around for thousands of years. I find it difficult to believe that just because we don't have a book telling us about wood kiln history, or the history of wood drying which is a broader subject but along the same line, that wood kilns never existed before the point in history of what we are aware. So just because we cannot prove it one way or another - I find it impossible to believe that air drying has been the only method of removing moisture from wood until the latter part of the 19th century.
> 
> If there's a work on the history of wood kilns, or a decent treatise on the of wood drying in general throughout history and you're aware of it please let us know. I don't know of one.
> 
> A note about Stradivarius: He was one of the geniuses I was referring to and his methods are still not completely known. Analysis of some of the wood he used shows salt crystals, gold, cyanide etc. so he used any number of methods still mostly unknown to dry/stabilize/preserve/fumigate his wood so he probably isn't a good benchmark for a general statement about wood drying techniques - he lived on his own planet.
Click to expand...


The short answer would be no it is not the same. I believe you are correct about the kiln usage throughout history. There had to be some way of predictable, quicker drying rather than just air drying. It may be as simple as a shelter to keep the rain off with some sort of air movement thru the shelter. Who knows?:i_dunno::i_dunno: I Guess I keep bringing it up because I believe that air dried lumber today isn't drastically different than air dried lumber from days past. While there is a difference that should be acknowledged, the comparison for modern practical purposes is reasonable as an explanation of how air dried lumber today will react to a woodworkers project.


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## Kevin

Treecycle Hardwoods said:


> ... I Guess I keep bringing it up because I believe that air dried lumber today isn't drastically different than air dried lumber from days past. While there is a difference that should be acknowledged, the comparison for modern practical purposes is reasonable as an explanation of how air dried lumber today will react to a woodworkers project.





So you think period furniture several hundred years old, some of it still in pristine and even museum quality condition, would have survived the ravages of time and abuse had it been built with the wide ringed, low resin, less dense (and however else it's inferior that we don't even know about) lumber of today? 

I say there's no way and the reason I think it matters, is because if what you say is true, modern kilns and kiln schedules wouldn't be necessary. We could still use nothing more than air dried wood and hide glue, and our projects would survive centuries. I just can't make myself believe that, so we can just have a friendly difference of opinion on it.


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## Treecycle Hardwoods

Kevin said:


> Treecycle Hardwoods said:
> 
> 
> 
> ... I Guess I keep bringing it up because I believe that air dried lumber today isn't drastically different than air dried lumber from days past. While there is a difference that should be acknowledged, the comparison for modern practical purposes is reasonable as an explanation of how air dried lumber today will react to a woodworkers project.
> 
> 
> 
> 
> 
> 
> So you think period furniture several hundred years old, some of it still in pristine and even museum quality condition, would have survived the ravages of time and abuse had it been built with the wide ringed, low resin, less dense (and however else it's inferior that we don't even know about) lumber of today?
> 
> I say there's no way and the reason I think it matters, is because if what you say is true, modern kilns and kiln schedules wouldn't be necessary. We could still use nothing more than air dried wood and hide glue, and our projects would survive centuries. I just can't make myself believe that, so we can just have a friendly difference of opinion on it.
Click to expand...


I agree to disagree  You have a very valid point on the question of whether or not our projects would last centuries using the same techniques as the old craftsman with the only difference being our modern wood. Many of the pieces of furniture from those time periods didn't make it to modern times and were scrapped long ago.


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## Kevin

And those pieces were probably built by hacks or they saw too much abuse in one of many ways or a combination thereof. Without injecting variables and changing the equation, wood movement itself is way different (more) in today's plantation and 3rd growth timber than the old, IMO. I'll leave it there.


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