# Wood Drying Question



## bpajwhite (Nov 8, 2006)

Hi All,

I thought I would solicit some opinions about the wood I am drying for my planned workbench. I recently read Chris Schwarz' second workbench book (the red one) and Lon Schleining's workbench book (from 2004) and I think I know more or less what I want to build. It's a combination of several of the benches from both books, but most similar the Rubo on the front of the Schwarz book. 

I priced out hard maple and my local hardwood dealer and found that it was in the $5-$6 per board foot range. I estimate my bench plans to require about 175 - 200 board feet. $1000 is more than I'm willing or able to spend on materials. 

With that in mind, my first inclination was to build as inexpensive bench as possible out of construction lumber and plywood, and someday later, build what I really want out of hard maple/cherry. However, I think that I have come up with a good compromise that is inexpensive and may never need replacing.

I saw (pun intended) an add on craigslist for clear cedar or douglas fir by a guy who is starting up his own small sawmill operation. I phoned him and gave him a list of all the pieces of lumber that I wanted. He called me back and quoted me a great price so I drove over to meet with him. He had a couple of doug fir trees that he had felled the previous day so I got to watch as he turned them into lumber for my work bench. I had him mill me:

17 – 2x5s for the bench top (They actually measure about 2 ¼ x 5 ¼) that I plan to face laminate to make the bench top.
5 – 3x6s (They actually measure about 3 ¼ x 6 ¼) that I will glue up to make 6x6 legs.
5 – 2x6s (They actually measure about 2 ¼ x 6 ¼) for stretchers and maybe vise jaw.

When all was said and done, I took all of the mis-cuts and some extra pieces with a live edge. I ended up with well over 200 board feet of clear doug fir at a price that worked out to about 45 cents a board foot. While I was very pleased with the deal I got, I was certainly concerned about the fact that the lumber was green and would have to dry before using it.

I got all the wood home and got it into a stack in the garage that very night. Here’s what I ended up with:





























I spent a lot of time googling how to dry lumber and read some interesting articles about forced air drying doug fir. They claimed to dry doug fir to 19% - 23% moisture in 14 – 21 days. Here’s one of the articles. http://ir.library.oregonstate.edu/xmlui/bitstream/handle/1957/6106/Air_Dry_Lumber_ocr.pdf?sequence=1 

I ordered a moisture meter so that I could monitor the wood as it dries. I set up the drying stack with a box fan at one end and put a dehumidifier at the other. Here’s how it looks:





























Today is 14 days since the lumber was milled. This evening, I took some readings throughout the stack. The end grain on the 3x6 material is down to 17%. 











I have read that the end grain dries way faster than the rest of the board, so I took additional readings halfway down the board. This is where I have run into a problem that I did not foresee. The next two pictures are of the same board (I guess timber might be a better word at this size). The two pictures are shown with the moisture meter in opposite sides of the wood. It sort of difficult to see, but in the second picture, above the streak of sap, you can see where the heartwood meets the sapwood. The sapwood is a creamy yellowish color and the heartwood has a pinker hue. I was surprised to see that the heartwood is already down to 20% moisture, but the sapwood is still at 36%. 



















In using green doug fir, should you wait until all of the readings match? How long do you think that will take? I have read nothing about heartwood and sapwood drying at different rates, but I suppose that makes sense when you think about how a tree works.


One of the other concerns I have read about was the tendency of wood to check of the wood as it dries. I did read that doug fir is fairly resistant to this. So far all I can see is slight checks in the end grain. None appear to be going into the face or edge. Here’s some examples:






































I don’t think that these are much cause for concern as long as they don’t start splitting further up the timber. Am I wrong? 
I also took some readings further down in the stack. The edge of this 2x5 reads 19%:











For reference, I also put the meter in the end grain of one of the stickers that I used to build the stack. It reads 14%. I used pieces of kiln dried commercial 2x4s that have been in my shop for at least six months to make the stickers. They should provide a fairly accurate representation on the ambient moisture level. 











Anyway, I’d welcome your thoughts or opinions on this topic. How long would you wait to start milling the lumber? I’m not in a major rush, but I would rather my wait time be weeks not months. Do you think I’ll end up with a banana if I only wait a few more weeks? I did read an article or forum entry somewhere in which the author made the argument that in this sort of use (gluing up a benchtop) the fact that all the pieces are glued to each other helps to immobilize them as they continue to approach ambient moisture levels. 

Feel free to chime in. And thanks in advance for your input.


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## chicago (Jul 5, 2012)

While I think your stickering and air circulating set up is very good, if it had been me I would have slapped paint or parrafin on the ends of all the boards. This slows down the moisture loss and helps prevent the end checking you are already experiencing. You will undoubtedly always show a lower moisture content on the ends as opposed to the middle of the boards which is due to the more rapid moisture loss. IMO the ideal situation would be to have a uniform moisture reading across the boards as they dry, but to even approach this uniformity, the ends would have to be sealed.

Nearly 99% of my wood stock comes from trees felled in my area and the first thing I do is coat the ends of each log and this has always curtailed the checking without exception.

Best of luck with your work bench.


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## Da Aardvark (Oct 11, 2012)

Good point on the end coating.
You might also consider banding them together so the top boards (without substantial weight on them) won't move.

When you are dealing with fresh cut lumber, expect some twisting and cracking when drying. I generally tarp over the wood, and install very small space heaters on each end, and cut a slit in the top for moisture release. Space heaters are dry heat. I will daily move the space heaters from the ends to the sides and try to even out the drying process. I keep moving them to not overheat one area over another. I also monitor the temp and try to keep it under 100deg, and most times closer to 85-90deg. 
Buying non kiln dried lumber is a rough way to go, but at that bd. ft. price, I would go for it. Expect some loss.


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## ACP (Jan 24, 2009)

Those checks aren't fatal yet. Get some latex paint or anchorseal on them ends ASAP. Or at the very least turn off the fan and dehumidifier to slow the drying process on the ends. I am not real schooled on the drying times of soft woods, but hardwoods have been commonly said to be 1" per year. I would expect it to be awhile until they dry. Doesn't the book say you need to use some green wood for the bench though? I don't recall but I thought the legs were supposed to be greenish.


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## bpajwhite (Nov 8, 2006)

Thanks for all the input guys. I have been moving the fan from one end to the other or to the side every day or two in an attempt to even out the drying process. I initially thought about putting some sort of sealant on the ends but had reservations. By sealing up my garage and using the dehumidifier and fan, I have essentially created a dehumidification kiln. If seal up the ends wont that significantly slow the drying time? My hope was to be able to use the lumber after 2 months of drying (or less if feasible). 

I have also read about the 1 year of drying per inch of thickness, but my understanding is that guideline is for outdoor stacking of hardwoods with no forced air movement. When I considered buying green doug fir for this project I searched online for information on drying this type of wood. Some of the information I found, said that doug fir has a moderate, though not heavy, tendency to check, but otherwise dries stably and quite rapidly.

So now the dilemma. Do I seal the ends and risk slowing the drying process or take my chances with the checking, figuring that all my boards are over length? 

I do appreciate your thoughts.


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## J.C. (Jan 20, 2012)

Seal the ends. I've never kiln dried anything in my life but, it's my understanding sealing the ends helps it to dry out evenly. By not sealing the ends, the only thing your doing is drying out the ends far faster than the rest of the board and causing the checks.


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## mike1950 (Aug 29, 2010)

Where do you live? I ask because the humidity will have a lot to do with wood drying times. Softwood will dry faster but it will take a while in the winter. The end of the board my be dry but the center sure is not. Patience is the name of the game. I would not build green- to much work put into bench to have top bent, crooked and cracked. I used Doug fir on my bench top on purpose. It is relatively stable and hard but if I drop a piece of walnut I am working on - on the bench it dents the bench not the piece. Watch craigslist for cheap wood. Good luck- the effort and wait will be worth it- I do not see how I got along without mine..............


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## J.C. (Jan 20, 2012)

One other thing you have to watch out for if you try to dry to fast is case hardening. I know some types of wood are more sensitive than others but don't know where doug fir falls on the list. 

Case Hardening in Timber
Case Hardening explained
Wood Drying


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## bpajwhite (Nov 8, 2006)

Mike

That's a nice looking workbench. I live in western Washington close to the water. It has already started raining so I guess it will stop in about April. Needless to say, its rather damp up here in the winter months. That's why I set up the dehumidifier. I guess I should have come up with this plan 5 months ago, oh well!


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## del schisler (Nov 5, 2009)

*drying wood this is the guy to talk to*

go here and talk to daren he sell planes for the kiln for the dehumidifier unit type kiln for $25.00 I see you have most of it all ready here is the link http://woodbarter.com/showthread.php?tid=47


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## CNYWOODS (Apr 22, 2012)

Wax your ends, it may take a lot longer than you think anyhow, does help with a uniform dry. With any lighter woods I put in my kilns I use a PVC sticker( 1" pipe riped in half), to prevent sticker stain, spaced every 12". Just a thought, the spiral, solid and slotted ones will stain.


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## mike1950 (Aug 29, 2010)

bpajwhite said:


> Mike
> 
> That's a nice looking workbench. I live in western Washington close to the water. It has already started raining so I guess it will stop in about April. Needless to say, its rather damp up here in the winter months. That's why I set up the dehumidifier. I guess I should have come up with this plan 5 months ago, oh well![/QUOTE
> 
> Thanks, I kinda guessed you were close. Darrens plans will solve your problem


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## scsmith42 (Jan 24, 2011)

I operate a sawmill and kiln drying business, and there are a few things that you're doing correct but many more that you're doing wrong. 

For starters, you are attempting the flow air the wrong direction through your stacks. Airflow should be from side to side - maximizing the air flow across the widest faces of the boards. Your end checks are being caused by the excessive air flow past the ends of the boards. Place three or four fans adjacent to your stack; restack the boards (as I explain below), and move the fans closer or further as needed to get the flow through the stack to the desired level.

Second, seal the ends of your boards ASAP. Checks in the ends of boards are similar to cracks in glass - once they start they tend to keep growing. If it were me, I'd actually trim around 1" or so off of the ends of the boards before sealing, so as to get rid of the checks that have already started.

The best product to use for end sealer is one made for that purpose. The leading product is Anchorseal Classic by US Coatings. A 5 gallon pail will set you back around 80 bucks delivered. An alternative is Baileys’ End Sealer sold by Baileysonline.com. 

There are many "home remedies" including latex paint, roofing tar, paraffin wax, etc. Latex paint and roofing tar are hard on shop equipment, so you will need to trim the ends of your boards before joint/planing, etc if you use them. 

Do not measure moisture content at the ends of the boards. Measure it from either the face or sides of the boards for a more accurate reading.

Moisture Meters are not accurate above the fiber saturation point (FSP) of lumber, which is around 32%. Thus, any readings that your meter provides you above 32% are suspect.

Doug fir is a fairly easy drying wood, which is in your favor. Regarding air flow, aim for around 350 FPS through your stack. You can measure this by holding a handkerchief behind the stack, flat and parallel to the stack. You should have about 2" of deflection at the bottom of the handkerchief.

Your stacks have too much gap between the boards. Each layer should be put down so that one edge of the board is touching the adjacent board. This is important because if forces the airflow to go all of the way through the stacks, wicking moisture off of the faces of the boards.

I can't tell how thick your stickers are, but you want to shoot for 3/4" - 1" thick, spaced about every 16" - 20", with the stickers positioned immediately above one another. Be sure to have a sticker within a few inches of the ends of the boards. Yours appear to be 12" or greater. Also be sure to have cribbing below your stacks - at least 6" and 9" or more is better. There should be cribbing underneath every sticker.

When using a dehumidifier for drying, typically you drop the RH% level in 3 stages. Start off around 85 - 90%, until the lumber dries from green down to 35%. Then drop to 60% RH% until the lumber dries down below 25%. Below 25% shoot for 30% - 40% RH.

Most of the defects that occur during the drying process are due to drying too rapidly at MC%'s above 35%. However the defects are not revealed until the MC% is below 25%.


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## bpajwhite (Nov 8, 2006)

J.C.,

Thanks for the info on case hardening. I had not found anywhere that explained it that well. I think I will probably paint the ends in the morning.


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## bpajwhite (Nov 8, 2006)

scsmith42,

Wow, thanks for all that fantastic info. I really appreciate you taking the time to explain all of that. My stickers are ripped from 2x4s and are 3/4" thick. I will make some more tomorrow and re-stack the pile as you suggested. I was reading somewhere (I cant recall if in a book or online) but I remember the author saying to make sure that there was at least one inch gap in between the boards in each layer. Considering that all of these boards a fairly thick 2 - 3 inches, wouldn't you want that space so that those edges also act as a drying surface? I have been positioning the fan on the side at times, but will leave it there from now on.

I have had my dehumidifier running on high the whole time. I don't have a hygrometer so I'm not sure what the RH in the garage is now. I might turn it off for a couple of days and use just the fan to try to reduce and checking or case hardening caused by differences in moisture content at the surface and in the center of the board.

One term that I did not know from your post is cribbing. What is that? 

"Most of the defects that occur during the drying process are due to drying too rapidly at MC%'s above 35%. However the defects are not revealed until the MC% is below 25%." - Since the wood was fresh from the tree when I started this, and is now below 25% in only two weeks, I'm not sure whether or not I have already screwed this up. We'll see. 

Thanks again for all your input.


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## scsmith42 (Jan 24, 2011)

bpajwhite said:


> scsmith42,
> 
> but I remember the author saying to make sure that there was at least one inch gap in between the boards in each layer. Considering that all of these boards a fairly thick 2 - 3 inches, wouldn't you want that space so that those edges also act as a drying surface?
> 
> ...


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## bpajwhite (Nov 8, 2006)

Ok, I took the stack apart and have restacked it as suggested. I kept the green wood that I was using for cribbing, but have added three 2x4s and another row of stickers before I put my first course of lumber. The first course is now 7 ½” off the ground.
































I restacked everything with the edges of each board touching the next. I increased the number of stickers that I was using and have placed one within 2-3 inches of each end and about every 15 inches in-between. I put the better boards lower in the stack so that the weight of everything on top should help to keep them flat. All of the scrap pieces, leftovers, and off-cuts that I got from the sawyer, I put on top since I’m not particularly concerned about those. Once this was done, I painted all of the ends with some latex paint that I had in the shop. I’ll be sure to trim that of before I joint and plane the boards. Thanks for that tip.


So here’s how it looks now. 












I put my box fan on the side and have added a smaller fan for increased air circulation.













I also took a few more moisture readings. Here’s a reading in one of the heartwood boards:













And here’s one from one of the boards that has a sapwood edge:













One thing that did surprise me while re-stacking some of the lumber what how light some of it felt already after only two weeks. 


I have removed the de-humidifier from the garage for the last couple of days in an attempt to let the moisture levels in the boards even out and hopefully become more consistent throughout each board. I plan to put it back in another day or two. 


There is still quite a difference in moisture readings between the heartwood and the sapwood. These to pictures illustrate the point quite well (the meter is inverted in the pictures):












As you can see, it’s at 21% in the heartwood, but a second reading, less than two inches away but in the sapwood, shows 34%:













I think that most of the wood movement that was going to happen, has happened by now. The wood really does feel quite dry when handling and lifting it. That said any further drying should be more stable now. And I’ll definitely be better prepared the next time I do this.


I welcome any thoughts or comments.


Thanks.


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## Midlandbob (Sep 5, 2011)

I've been reading most of this thread. I've been drying wood for years with no problem and have read many articles and discussions of the topic.
You have gotten quite a bit of advise.
There are a few things to say. The best advise was to slow down. You cannot dry wood fast without careful measurements and the ability to add steam to slow the process down at times I thou want to dry it fast like a kiln operation.
The issue of sticker staining happens in the very first stage of drying when there is free water in and on the wood to promote the growth of fungi. Once the wood is surface dried and below 20% it is not a problem. The initial 80% of the water is free water and goes off fairly quickly. That's why you note a dramatic loss in weight.
You only need a gentle fan to ensure some air movement around the wood stack. A small fan on oscillation mode will work. Two inch wood probably needs 6 months or so to get down to outside moisture content of 12% relating to the 60-70% humidity. 
To get it down to use for inside projects you need to restock it inside at 30-50% humidity for another 6 months or so. It may need longer for your two inch boards.This is best done over the winter especially if you want to do it in a basement. You want to get it to 6-8%. Remember if you put it outside or in the garage it will quickly go back to 12+%.
There are a lot of misunderstandings of the stability of wood moisture and movement. 
The best book is probably still Bruce Hoadley's "Understanding Wood". It's a must or should read for any aspiring woodworker. It has info on different wood and their specific character as well as very understandable discussion of wood drying with the topics such as case hardening etc. many other valuable aspects of wood and machining wood technology are interestingly covered.
Any questions just ask - I'm not sure if we can email.


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## bpajwhite (Nov 8, 2006)

Thanks Bob,

I plan to build a workbench from the wood, so it will be staying in the garage. I live in the pacific northwest and the ambient relative humidity is quite high. I'm not aiming for 6-8% moisture content. Once the wood reaches the 12-14% range, I plan to start the project. 

I'll be sure to check out the book you suggested. 

Thanks again.


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## smokey1945 (Feb 20, 2009)

Thank you guys for all the information!! I bookmarked this one!:yes:


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## HicksBenedict (Aug 11, 2021)

bpajwhite said:


> Hi All,
> 
> I thought I would solicit some opinions about the wood I am drying for my planned workbench. I recently read Chris Schwarz' second workbench book (the red one) and Lon Schleining's workbench book (from 2004) and I think I know more or less what I want to build. It's a combination of several of the benches from both books, but most similar the Rubo on the front of the Schwarz book.
> 
> ...


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## HicksBenedict (Aug 11, 2021)

Never thought of such an idea...all along i've just known that wood drys on its own through the natural light. this is a very effective way of drying wood i must confess.


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