Kiln vs. Air Dry

Which do you prefer

  • Air Dried

    Votes: 11 23.9%
  • Kiln Dried

    Votes: 12 26.1%
  • Either of the 2 is fine by me

    Votes: 23 50.0%

  • Total voters
    46
I'm not trying to fan flames but I've always been curious. If I have a board that is kiln dried to 8% moisture and an air dried board. If I place them in the same environment say my garage for example. Would they reach the same moisture content if left long enough? How much moisture will a kiln dried board absorb from the air?
 
John a kiln dried board will come up to what ever ambient MC is at your place within a week or so. Most kiln dried hardwood SHOULD be nothing more than 6.5% when leaving the kiln and if you have away of controlling you RH to 35% it should remain at 6.5% but in my area, in uncontrolled RH it will come up to 10 or 12% MC. Coming up to that MC from 6.5% is not as big a problem and if it was only air dried to 12% or what ever MC is for the area you live in.

Softwood is considered kiln dried at 10 to 12% and you don't want something like pine to be much bellow 10% or it is to dry your com# softwood is considered dry at 19% which most of the time can be achieved by air drying.

Hope this answered your ??

Jay
 
Softwood is considered kiln dried at 10 to 12% and you don't want something like pine to be much bellow 10% or it is to dry your com# softwood is considered dry at 19% which most of the time can be achieved by air drying.

Hope this answered your ??

Jay

Funny I like my pine to be at 6% before I use it:thumb:
 
And the opinions roll on..... This topic is similar to question of glue preferance and "The Best" finish... :thumb:

Opinions are like... Uh...preferences, Everybody's got one.

Here is an interesting publication from US Forrestry...
http://www.finalfloor.com/techguide/maintenance/moisturecontent.pdf

and yet more "opinions" at Wood Central
http://www.woodcentral.com/bparticles/drywood.shtml

and a lengthy long read that has some good info...
http://www.fpl.fs.fed.us/documnts/fplgtr/fplgtr113/ch12.pdf
(No I am not the William T. Simpson who is the arthur of this report, but he does echo my years of experience and education)

Each of these documents refer to the same consideration that the MC must meet the ambiant MC of the environment where the project is kept. Each also prefers Kiln dried for the stability and reduced waste.

This is a good subject matter that each of us need to consider. :wave:
 
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Thanks Jay for the reply.

Let me see if I have this correct. What your saying is if I take my two boards and put both in my garage that isn't humidity controlled both boards will reach the same MC over time?

If a board only has a 3 to 4 % MC difference from inside the house to outside is it really that big of a deal? Again I've always wondered about this.

I get kiln dried cherry from a guy who lives about 12 miles from the house. He stores his lumber in a warehouse and it's not temp controlled by any means. I've heard that you should let wood acclimate for a little while before you build with it after you bring it home. I've wondered why I should let it acclimate to my garage because I've taken it from one unconditioned space to another 12 miles apart? The acclimation part usually isn't an issue because I've got to be the slowest woodworker on earth.:D
 
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Thats right John. The difference between that warehouse and you garage is what heat you what ever you are using and if the warehouse is open or what. It will make some difference.
The 3 to 4% could make some difference you more than likely you will get by with it.

Chuck I am only going by what they told me back when I used to buy semi loads of pine out of Oregon and what I had learned when using furniture grade pine I was taught to request it to be KD to no lower then 10% or it would get to punky. I know if pine got to dry it would sand away REAL fast and it didn't glue up or hold screws & nails as well and it seem to lose strength too me.

Jay
 
Thats right John. The difference between that warehouse and you garage is what heat you what ever you are using and if the warehouse is open or what. It will make some difference.
The 3 to 4% could make some difference you more than likely you will get by with it.

Chuck I am only going by what they told me back when I used to buy semi loads of pine out of Oregon and what I had learned when using furniture grade pine I was taught to request it to be KD to no lower then 10% or it would get to punky. I know if pine got to dry it would sand away REAL fast and it didn't glue up or hold screws & nails as well and it seem to lose strength too me.

Jay

wasnt sure what caused it but i have seen red oak like that jay it sanded like it was just wood streaked bondo.. fortunatly it was not very much of it that way i pitched it..it had been kiln dried as well
 
It is my understanding that the drying method varies almost as much as woods have different chemical and structural makeups. (ain't nature cool!!)

It is common practice for commercial operators to kiln dry and steam walnut because they gain salable volume by changing the white sapwood into dark wood. I also have been told that kiln drying walnut without steaming will preserve most of the desirable color.

Kiln drying will permanently set the resins in many woods making them inherently more stable in regards to moisture take up with changes in humidity. It hardens the cell walls. It will also kill any bugs, and usually kills any fungus.

Conventional kiln drying is limited in regards to board thickness. For instance, the only way to dry 3" plus thick white oak is with a vacuum kiln. Conventional drying of thick boards often yields honeycombing and stress fractures inside the board. Of course some woodworkers don't like the appearance of vacuum dried lumber. :dunno::dunno:

I didn't vote because I use boards dried both ways depending on usage.
 
As many have stated, there are uses and reasons for both. However, for me, the most compelling reason for KD is insects in certain types of wood. For instance, I would be VERY shy about using AD oak due to the potential for PPB infestation. A couple of years ago, I had about 1000BF of AD oak I brought into the shop to build with only to have lots of little piles of sawdust a week or two later. It immediately went back outside and off to a kiln. Thankfully I have seen no evidence that the little buggers migrated to anything else. Thankfully they don't like pine so the framing was pretty much safe.
 
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