# Acclimating Wood



## nathanvaughan (Sep 2, 2015)

I work with re-claimed wood and hardwood. I have typically been in the habit of working with wood that has either been air dried or kiln dried without acclimating in the shop prior to use. I've noticed that even after using the wood, 1 or 2 times out of 10 I'll see movement in the wood in some way.

My question is, is there a standard procedure in acclimating dry wood before using it? Is it the heat or change in environment that makes a difference?

Thank you,

Nathan


----------



## Steve Neul (Sep 2, 2011)

I think it's not really acclimating the wood to your shop is the problem. I think there is an issue with the reclaimed wood. If you are using say pallets you may getting wood that is green. They don't season wood for pallets, they just cut the wood from logs and nail em up. If you are working with reclaimed wood you probably should invest in a moisture content meter. That way you could know if the wood you are using is seasoned or not.


----------



## Tennessee Tim (Dec 15, 2010)

"Reclaimed" name covers a large variety of wood and styles, as Steve mentioned it can be pallets to barnwood to a structure as a house or warehouse or even a log meant to be burned but saved and sawed......kinda like in the south a "coke" doesn't mean "coca cola" brand necessarily it means a carbonated type of drink in a bottle or can..... same as "sawsall" is not always Milwaukees brand trade name saw BUT any reciprocating saw.

I'm with Steve....you need to know where the wood is to start with in MC.

"Acclimating " is just to get wood to a room/area MC balance BUT the wood should have been priorly at correct MC to start with (wood gains and loses moisture as it is shipped and stored BUT mostly to the exterior UNLESS it has sit in a enviroment that was extremely wrong MC for a long period of time then it can soak deeply to core). Acclimating isn't for a drying stage of wood.

Post a little more info on your wood type and style....also how it's actually being used and joined together.....pics help the most.


----------



## nathanvaughan (Sep 2, 2015)

Thank you for the replies. I use mostly re-claimed fence boards and barn wood. The wood I use is typically decades old and naturally air dried. I store my lumber outside mostly and if it is rained on, I'll dry it in my shop for a month or two prior to use.

In particular, I made a cabinet from re-claimed redwood fence boards which were dried outdoors. the piece was a face-frame style with inset doors. I had movement of about a 1/4" (bigger gaps around door panels). I will get some pictures later on the computer but I think I am just not getting rid of that last bit of moisture.

Note- I sealed the piece with a Minwax Polyurethane. 

Thanks,

Nathan


----------



## ColorStylist (Jul 19, 2014)

Most barn wood or reclaimed wood, even if its been hanging on a barn for 100 years, has a moisture content of 13-20%, and that is not dry enough to be used indoors. So in saying that, you still need to allow for your wood to acclimate. 

Here is a write up about the process of acclimating flooring, which in a sense can be the same proceedure your looking for.

http://www.oldewoodltd.com/what-to-know/resource-library/hardwood-floor-acclimation


----------



## Tennessee Tim (Dec 15, 2010)

ColorStylist said:


> Most barn wood or reclaimed wood, even if its been hanging on a barn for 100 years, has a moisture content of 13-20%, and that is not dry enough to be used indoors. So in saying that, you still need to allow for your wood to acclimate.
> 
> Here is a write up about the process of acclimating flooring, which in a sense can be the same proceedure your looking for.
> 
> http://www.oldewoodltd.com/what-to-know/resource-library/hardwood-floor-acclimation


Acclimating flooring IS NOT the same....the flooring has been KD to a 6% through and through where barnwood is in the general MC range you mentioned after all those years IF it's not rained on. Acclimating flooring to room is TOTALLY different then drying the wood on down to indoor MC especially if it's been wet....well that's not dry at all!!! LOL!!!

Nathan, fence boards are going to be higher MC than indoor barnwood due to keeping being rained (moisture) on seasonally. IF it were me and I was to do the minimal to get it prepped I'd set me up a solar kiln type storage and dry it and leave it there until needed. It would be dry and good balanced MC. If you have room to stack it in the rain surely you can build a solar kiln......or even a small DH kiln to get MC correct but not able to sterilize which your not doing anyway. You can build a small setup even in a shop....I seen one that was under a large work bench and had a rough capacity of a few hundred bd ft...the gent loved it. If you have the room to store indoor to acclimate?? the same area can be tarped and DH'd for better results.


----------



## ColorStylist (Jul 19, 2014)

Tennessee Tim said:


> Acclimating flooring IS NOT the same....the flooring has been KD to a 6% through and through where barnwood is in the general MC range you mentioned after all those years IF it's not rained on. Acclimating flooring to room is TOTALLY different then drying the wood on down to indoor MC especially if it's been wet....well that's not dry at all!!! LOL!!!



I guess we agree to disagree with each other on this. When you kiln dry flooring, you take the moisture down to 6-7%. *The flooring will likely acclimate back up to around 10%* once its taken out and sat aside, but it should not cause any problems. Most barnwood is around 13% MC straight off of a building unless of course its been currently rained on, but should dry out in a couple of days easily. Therefore, the process can be the same or similar when acclimating flooring vs barnwood. Bottom line is you need to bring it in and let it sit.

Contrary to popular belief, acclimating is not a matter of time, but a matter of moisture. Ideally, you will want the moisture content of your wood to *be within 3% +/- *of the moisture content of the environment in which the wood is going to be residing in. One piece may work in my house, but may move when the same piece is moved into your house for example. Kiln dried wood will move also, but maybe not quite as much as air dried. You need to reduce the moisture of the barnwood further by putting the lumber someplace warm and dry - attic, warm and dry room, etc. I mostly air dry mine then put it in a small room with a dehumidifier running in the summer and heated in the winter that gets my wood down to 6% when needed. Kiln drying does offer the advantage of killing any insects. It is faster and more uniform perhaps, but not necessary.

To the OP, when building things, plan on the wood moving from season to season. If you acclimate the barnwood in the winter and build using it, it will not move as much, probably hardly any at all. In the summer you will find the barnwood will move alot more. More care needs to be taken in the summer to acclimate the wood properly.


----------



## nathanvaughan (Sep 2, 2015)

Thanks for the reply. I have looked into solar kilns some and will do more research on that. Since air drying only bring wood to a moisture content of 12-15% is kiln drying the only way to reach that 6-9%? What about drying in a warm shop for a few weeks?

Also, I know that unsealed wood will continue to gain and release moisture, but what do you think is the highest MC to seal soft wood successfully without movement?


----------



## nathanvaughan (Sep 2, 2015)

Thanks for the reply. That makes sense as far as getting down to the MC. I usually dry my lumber in a heated shop for a few weeks prior to use. Also, I live at an elevation of 2000 feet in northern CA and a lot of my customers live in the mountains at an elevation of 7000 feet so I know that they are experiencing extreme temperature changes throughout the year especially if they are gone for the winter and not heating the house.


----------



## ColorStylist (Jul 19, 2014)

nathanvaughan said:


> Thanks for the reply. I have looked into solar kilns some and will do more research on that. Since air drying only bring wood to a moisture content of 12-15% is kiln drying the only way to reach that 6-9%? What about drying in a warm shop for a few weeks?
> 
> Also, I know that unsealed wood will continue to gain and release moisture, but what do you think is the highest MC to seal soft wood successfully without movement?


For barnwood and reclaimed wood, a humidifier works wonders. To me, a kiln being used to dry out barnwood is over-kill.

A kiln will get MC down to 6%, but the wood will never stay at 6% as it usually rises back to around 10%. Drying lumber, either naturally (air drying) or in a kiln is the process to lower the moisture content to the surrounding environment. For much of the United States, the minimum moisture content of thoroughly air dried lumber is 12% to 15%. Kiln dried hardwood will usually be less than 10%. 

Without movement? Never happen as you will always get some movement. No finish will block moisture transfer; they just slow it down. Finished wood will eventually acclimate to EMC levels. Penetrating oils provide the least protection. Non KD lumber or Pressure Treated lumber generally is 15-19% moisture content. That 19% is a critical number as it’s general consensus among the Building Science experts that above 19% MC is the point where mold spores are activated and the rot processes start. I would not put a finish over anything that is over 15% MC.


----------



## Tennessee Tim (Dec 15, 2010)

ColorStylist said:


> I guess we agree to disagree with each other on this.
> 
> Sorry I don't agree.....this is 2 differ processes.....acclimation is a "rebalancing" of MC meaning the wood has been at OR below wanted MC before. He needs a "drying" process to bring it down to needed MC which the wood has NEVER been to internally before.
> 
> ...


----------



## Steve Neul (Sep 2, 2011)

Tennessee Tim said:


> ColorStylist said:
> 
> 
> > I guess we agree to disagree with each other on this.
> ...


----------



## Tennessee Tim (Dec 15, 2010)

Steve Neul said:


> Tennessee Tim said:
> 
> 
> > Excluding pallets, have you ever had any issues with used or old wood? Any old wood I've ever used has been the most stable stuff. It's new wood for me I've had issues with including kiln dried.
> ...


----------



## ColorStylist (Jul 19, 2014)

Steve Neul said:


> Tennessee Tim said:
> 
> 
> > Excluding pallets, have you ever had any issues with used or old wood? Any old wood I've ever used has been the most stable stuff. It's new wood for me I've had issues with including kiln dried.
> ...


----------



## ColorStylist (Jul 19, 2014)

Tennessee Tim said:


> this is 2 differ processes.


LOL, I know that acclimation and kiln drying is 2 different processes, I never said they were the same. I simply said that acclimating barnwood and reclaimed wood is about the same process as acclimating flooring, hence I posted the article about it above. Same would go for baseboard and crown molding before installing. The only difference would be the length of time it would take. If the OP had an MC meter, we would all know whats going on in a flash. 

I dont think its the MC thats giving him the problem. Its more of when the piece is getting to the buyer and the wood is moving. There could be changes in the way things are being built that would help with this problem.....like on raised panel doors for example, make the inserts go deeper inside the frames to allow for movement. The OP's wood could actually be "too dry" (if its being stored for months) and when the piece is built and arrives in a higher humidity environment, it will move and cause problems.

The OP has even stated that he has used kiln dried wood that moved.


----------



## Woodcutterron (Nov 21, 2009)

Quick observation. Not all "flooring" has been kiln dried to a 6% moisture content, which is particularly relevant when talking about reclaimed lumber. So any blanket declaration of such is simply wrong. Further, it's best to try to bring the final moisture content of reclaimed wood to the proximate conditions the piece being built will exist in, not the shop. Shop conditions are sometimes, even often rather different from living conditions.


----------



## ColorStylist (Jul 19, 2014)

Woodcutterron said:


> Quick observation. Not all "flooring" has been kiln dried to a 6% moisture content, which is particularly relevant when talking about reclaimed lumber. So any blanket declaration of such is simply wrong. Further, it's best to try to bring the final moisture content of reclaimed wood to the proximate conditions the piece being built will exist in, not the shop. Shop conditions are sometimes, even often rather different from living conditions.


Whether its 6% (which is what most wood is kiln dried to) or 8% kiln dried, all commercial flooring manufactured is kiln dried either before or during its manufacturing process. So it is relevant when talking about reclaimed lumber. The bottom line is the wood needs to acclimate to its surrounding environment, and even then, you cant stop wood movement! Here is a right up on moisture content and wood movement:

http://www.thisiscarpentry.com/2010/09/03/moisture-content-wood-movement/

The rest of your statement I can agree with.


----------



## Larry42 (Jan 10, 2014)

"The flooring will likely acclimate back up to around 10%"
You guys must live near the coasts. In my part of the country EMC is about 6.5%. The US Forest service has charts showing EMC for various parts of the country. At any rate it takes time for wood to reach EMC depending on how deep the moisture goes. usually not too deep in commercial flooring. Wood that has been out in the weather, barn wood, a lot longer. The forest service also has information on solar kilns, worth the read.


----------



## ColorStylist (Jul 19, 2014)

Air drying.....Air drying is the simplest and least expensive way to start drying your lumber. However, the lowest moisture content that can be reached is dependent upon the relative humidity in your area, which, for most of the United States, ranges between 65% and 75%, resulting in a moisture content of 12% to 15%. If you need lower final moisture content, such as 6% or 8%, you will need to use some type of dry kiln.

Kiln drying...... If the level of temperature and humidity control is high, these systems can be used to dry lumber from the green condition to 6% to 8% MC with excellent quality. 

Regardless, the MC will rise or fall to whatever environment its subject to over a length of time.
You must/should acclimate the wood, whether flooring or reclaimed wood, to the environment it will reside in. Acclimation is the same with any type of wood, just some types of wood takes longer to acclimate then others, but the process is the same. Flooring and reclaimed wood acclimates using the same process, only the time it takes to acclimate is different.


----------



## Rick Mosher (Feb 26, 2009)

I would invest in a moisture meter. They don't cost a lot and then you will be sure. Even when we would buy high end kiln dried lumber we would have some boards that were too wet to use and we would send them back. You don't want to spend a lot of time building something and have it self destruct or get bubbles of water under the finish.


----------



## ColorStylist (Jul 19, 2014)

Rick Mosher said:


> I would invest in a moisture meter. They don't cost a lot and then you will be sure. Even when we would buy high end kiln dried lumber we would have some boards that were too wet to use and we would send them back. You don't want to spend a lot of time building something and have it self destruct or get bubbles of water under the finish.


Thats right Rick......"If the OP had an MC meter, we would all know whats going on in a flash." I said this in post #15 above. Thats the only way to be sure.


----------



## Woodcutterron (Nov 21, 2009)

ColorStylist said:


> Whether its 6% (which is what most wood is kiln dried to) or 8% kiln dried, all commercial flooring manufactured is kiln dried either before or during its manufacturing process. So it is relevant when talking about reclaimed lumber. The bottom line is the wood needs to acclimate to its surrounding environment, and even then, you cant stop wood movement! Here is a right up on moisture content and wood movement:
> 
> http://www.thisiscarpentry.com/2010/09/03/moisture-content-wood-movement/
> 
> The rest of your statement I can agree with.





Well, I agree with the part of your post where you agree with me.  But the rest . . .well . . .we're talking "reclaimed" lumber here. And much of that lumber is very old. And this isn't an exception to the rule either. By it's very nature, "reclaimed" wood is probably gonna be fairly old. And much of it was dried by some guy named "Ezikiel" or whatever, during the 18th or 19th century, who may have just looked at you like a martian if you asked about moisture content percentage, particular on reclaimed wood from a residence or barn. Any assumption that reclaimed wood, unless you know specifically the source and history, whether is was properly dried, or even kiln dried, for that matter, is a roll of the dice.


----------



## ColorStylist (Jul 19, 2014)

Woodcutterron said:


> Well, I agree with the part of your post where you agree with me.  But the rest . . .well . . .we're talking "reclaimed" lumber here. And much of that lumber is very old. And this isn't an exception to the rule either. By it's very nature, "reclaimed" wood is probably gonna be fairly old. And much of it was dried by some guy named "Ezikiel" or whatever, during the 18th or 19th century, who may have just looked at you like a martian if you asked about moisture content percentage, particular on reclaimed wood from a residence or barn. Any assumption that reclaimed wood, unless you know specifically the source and history, whether is was properly dried, or even kiln dried, for that matter, is a roll of the dice.


Ever watch "Barnyard Builders" on HGTV or the DIY channel? It sometimes intrigues me as to how they went through extreme measures and detail back in the 1800's to build their homes, barns, and other things. 

My neighbor has several barns on his property scattered across 75 acres that were built in the late 1800's to very early 1900's. Some are still standing, while others has seen better days. He has taken some of the barnwood, resawn it (plainer,etc), treated the wood with Boracare, then sat it in his basement for about a week where he ran a dehumidifier for a couple of days. He then built a table out of the wood, I finished it for him, and it is now sitting in his home......that was around 4 years ago. Still looks the same as when I finished it for him.

So the question is, how should the OP acclimate his reclaimed wood?


----------

