Moisture in SYP for Workbench - Woodworking Talk - Woodworkers Forum
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post #1 of 27 Old 01-07-2019, 03:12 AM Thread Starter
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Moisture in SYP for Workbench

Questions first, details second:

  1. Is 8-10% and 12-15% MC SYP dry enough to use for a workbench in a non-insulated garage shop in Austin, Texas?
  2. Given that the MC ranges across a board, which figure should I use? Max? Average? What about small wetter spots?
  3. My cheap moisture meter states "Measurement accuracy: Ī4% for both hardwood and softwood". Does that mean a reading of 10% could actually be 6% or 14%? Does that make it almost useless for determining if wood is dry enough for woodworking?
I started building a Roubo-inspired workbench during my vacation which has 1 week remaining (back to work on 1/14). I was really hoping to have it done by then. The plan is to build a 4.25"x28"x6' top by gluing up 8/4 Southern Yellow Pine. The base will be made from doubled up 8/4 SYP as well.

I chose SYP because it is pretty darn cheap here in Austin, Texas and is recommended by Christopher Schwartz in his book on building workbenches. I was sourcing from lumberyards when I found my local Big Box store sells construction grade "kiln dried" #2 prime SYP for dirt cheap. I picked through the stacks and found some decently straight and clear 2x10x12' flatsawn boards that I could rip in half.

I wasn't considering moisture content because it was advertised as "kiln dried". When I got home I could feel that one of the boards was noticeably damp to the touch (not sure how I didn't notice at the store). I bought myself this cheap $45 pinless moisture meter to check it out. I moved the meter over the face from one end to the other. That board ranged from 35-40%... Luckily, that board was from a different bunk/stack than the rest. Of the others, about 1/2 read between 8-10% across the board with spots at 11% and the other half 12-15% with spots at 16%.

This is my first large furniture project so I started reading up on acceptable wood moisture content. I learned a lot but was also inundated with often conflicting information lacking context. Some put a dead stop on figures like 9% or 12%. My case may be atypical since I am building a beefy workbench and not fine furniture. As such, I don't mind cosmetic flaws like small cracks that might result from the wood settling as long as they are not detrimental to the integrity. Also, the bench will not be indoors and instead in my non-insulated garage shop and exposed to the changing humidity. This site states "In most of the U.S., when wood is outdoors but protected from the rain, the wood will attain an EMC of 12% when the RH is 65%" "in more humid locations ... wood outdoors can attain 16% EMC." So maybe the wood is actually about were it should be for outdoors in Austin? Idk

It seems quite a few people have built workbenches using construction grade SYP from a Big Box store without reporting any issues. Am I overthinking and over-worrying?

Let me know what you guys think and I appreciate any input.
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post #2 of 27 Old 01-07-2019, 07:24 AM
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You won't have a problem with kiln dried lumber however you have to mount the top to the table in a manor which allows for the wood to expand and contract. This is true regardless of the moisture content or the level of climate control you have.
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post #3 of 27 Old 01-07-2019, 11:50 AM
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For those like me who have to look up terms to understand the post:

SYP = Southern Yellow Pine
MC = Moisture Content
EMC = Equilibrium Moisture Content
RH = Relative Humidity
Idk = I Don't Know

Last edited by Tool Agnostic; 01-07-2019 at 11:52 AM.
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post #4 of 27 Old 01-07-2019, 12:45 PM
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I built mine from big box SYP 2x10ís & 2x12ís ripped to size. I didnít check MC. I just rejected the boards that didnít feel dry. I followed Schwarzí book rather meticulously, have had no problems. Iíve had it a few years now.
Since you are building the Roubo, youíll be mortising the legs into the top. There should no expansion/contraction problems.
I suggest you glue up in three or four sections. I used Titebond Extend for longer open time.



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post #5 of 27 Old 01-07-2019, 01:13 PM
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Quote:
Originally Posted by Tool Agnostic View Post
For those like me who have to look up terms to understand the post:

SYP = Southern Yellow Pine
MC = Moisture Content
EMC = Equilibrium Moisture Content
RH = Relative Humidity
Idk = I Don't Know

It would be very nice if people would have the consideration of others of spell out acronyms the first time they use them in a post. Exceptions are well know acronyms like FBI, CIA, etc.



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post #6 of 27 Old 01-08-2019, 01:14 AM
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Quote:
Originally Posted by Steve Neul View Post
You won't have a problem with kiln dried lumber however you have to mount the top to the table in a manor which allows for the wood to expand and contract. This is true regardless of the moisture content or the level of climate control you have.
I'm totally agree with you: allows for the wood to expand and contract
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post #7 of 27 Old 01-09-2019, 01:57 AM Thread Starter
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Originally Posted by Steve Neul View Post
You won't have a problem with kiln dried lumber.
Not sure what you mean. I have learned that "kiln dried" simply means it was dried in a kiln and not air dried. The actual MC can still be up to 19% once it leaves the kiln. http://www.alsc.org/greenbook%20collection/ps20.pdf This also does not take into account how the wood was stored after. I would bet the bunk that the 40% MC board came from was left in the rain. You can certainly have problems with "kiln dried lumber".

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It would be very nice if people would have the consideration of others of spell out acronyms the first time they use them in a post. Exceptions are well know acronyms
Well, given that this is a woodworking forum and all the acronyms I used are very common/well known in woodworking I did not think that was necessary.

I guess since Southern Yellow Pine (Longleaf Pine) is not as as prevalent in all areas some may not be familiar with SYP. I'll give you that one. But, literally everything I have ready regarding moisture content in wood uses the MC, EMC, and RH acronyms. Idk? Everyone on the internet knows that one, right? lol (lol = laugh out loud)

I've went ahead with my glue up. I'm sure it will be fine.
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post #8 of 27 Old 01-09-2019, 08:12 AM
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Quote:
Originally Posted by yo1dog View Post
Not sure what you mean. I have learned that "kiln dried" simply means it was dried in a kiln and not air dried. The actual MC can still be up to 19% once it leaves the kiln. http://www.alsc.org/greenbook%20collection/ps20.pdf This also does not take into account how the wood was stored after. I would bet the bunk that the 40% MC board came from was left in the rain. You can certainly have problems with "kiln dried lumber".



Well, given that this is a woodworking forum and all the acronyms I used are very common/well known in woodworking I did not think that was necessary.

I guess since Southern Yellow Pine (Longleaf Pine) is not as as prevalent in all areas some may not be familiar with SYP. I'll give you that one. But, literally everything I have ready regarding moisture content in wood uses the MC, EMC, and RH acronyms. Idk? Everyone on the internet knows that one, right? lol (lol = laugh out loud)

I've went ahead with my glue up. I'm sure it will be fine.
Yes the moisture can fluctuate from humidity levels however there is a difference between air dried wood and kiln dried wood because it changes the cellular structure of the wood having been baked in an oven and is more stable.

I think you are worrying about moisture content too much. Once the wood is seasoned regardless if it was air dried or kiln dried the amount of shrinkage is substantially less. This is the reason moisture content is monitored, to determine when it's seasoned. If you are making a large panel out of solid wood that would be a problem if it shrank 1/8" or more would cause issues then you would have reason to worry about moisture content. Your bench if you made it in such a manor that would allow for it to shrink that much the moisture content doesn't matter. If you had wood that you could feel the water in it as though it had been rained on then there would be reason for concern however if you let it sit for a few days and dry you wouldn't have a problem. It's not like green wood fresh out of a tree where it takes more than a year to air dry, once wood is seasoned it dries very quickly. Even pressure treated wood that is put in a container and had a chemical forced through to the center will normally dry in a month to where it's usable.
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post #9 of 27 Old 01-09-2019, 09:07 PM
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Dry or Green...It does not matter...

Quote:
Originally Posted by yo1dog View Post
...Is 8-10% and 12-15% MC SYP dry enough to use for a workbench in a non-insulated garage shop in Austin, Texas?
...
Hello Yo1dog,

If you put work benches in the search line of this forum, there is a lot of good discussions covering all of this...

I didn't really need to go past your first question...If wanting to get into all the other stuff you asked about...Plenty out there that covers it, and many here that can discuss it...

The point has already been made...Wood Moves...period.

That is all you really have to keep your mind focused on. Dry or green and how much moisture is in it doesn't really have a bearing on all this...especially for a work bench that is following any semblance of a traditional version...

I would also close with, that "Work Benches" and/or the majority of them ever made through history (and the ones we make) where not made with air dried wood (and certainly not kiln dried!!??)

The woodworker dropped a tree, hewed/rived the parts and assemble the bench...What they understood was that the joinery must compensate for movement...
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post #10 of 27 Old 01-10-2019, 09:34 AM
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Quote:
Originally Posted by yo1dog View Post
[...]Well, given that this is a woodworking forum and all the acronyms I used are very common/well known in woodworking I did not think that was necessary.

I guess since Southern Yellow Pine (Longleaf Pine) is not as as prevalent in all areas some may not be familiar with SYP. I'll give you that one. But, literally everything I have ready regarding moisture content in wood uses the MC, EMC, and RH acronyms. Idk? Everyone on the internet knows that one, right? lol (lol = laugh out loud) [...]
I had to look up SYP and EMC. They were easy enough to find. I included "Idk" to elicit a smile.

Nonetheless, I try to define my acronyms the first time I use them. You never know when a beginner might be reading your post or someone might find it through an outside web search. They may need help understanding terminology that we take for granted.

I still need help with terminology, so I assume others do too.
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post #11 of 27 Old 01-10-2019, 08:35 PM Thread Starter
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Originally Posted by Tool Agnostic View Post
I had to look up SYP and EMC. They were easy enough to find. I included "Idk" to elicit a smile.

Nonetheless, I try to define my acronyms the first time I use them. You never know when a beginner might be reading your post or someone might find it through an outside web search. They may need help understanding terminology that we take for granted.

I still need help with terminology, so I assume others do too.
Fair enough. IDK did give me a chuckle.

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Originally Posted by Steve Neul View Post
Yes the moisture can fluctuate from humidity levels however there is a difference between air dried wood and kiln dried wood because it changes the cellular structure of the wood having been baked in an oven and is more stable.

I think you are worrying about moisture content too much. Once the wood is seasoned regardless if it was air dried or kiln dried the amount of shrinkage is substantially less. This is the reason moisture content is monitored, to determine when it's seasoned.
Thanks for the additional information. Makes sense. I also think I was worrying too much and went ahead with the project. I plan on using pinned mortise and tenon joints throughout.

Made some progress:
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post #12 of 27 Old 01-11-2019, 11:24 AM
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When you pin your joints you might consider drawboring them. Itís a simple process & results in a very tight joint that need no adhesive.




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post #13 of 27 Old 12-10-2019, 12:37 AM
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Can't find any topics related to the lumber drying process... I am new to woodworking, and can't understand if I need a couple of dehumidifiers and a fans for that. Only know I need a moisture meter...
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post #14 of 27 Old 12-10-2019, 08:47 AM
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@Thomas_Z

To make a long story short, there are two main forms of lumber drying. One is open air drying and the other is kiln drying.

Open air drying is exastly what it implies. More or less lumber is stacked in the open with a cover on top and left to dry naturally. Normal estimate is about 12 -14% final moisture content (MC) based on one year for each inch of thickness.

The other is kiln drying. Again , this is the short of it. The kiln is exactly as implied, a relatively low temp oven. drying time depends on the set-up usually under a month. Normal estimate is about 7-8% MC.

8% MC is about right for furniture grade wood.

Can you use normal lumber from the lumber yard for work benches? certainly.
Do people use normal lumber yard lumber for furniture? Some do, but I'm sure it is the minority. I personally would not.

Will you need fans and de-humidifiers? Most woodworkers dont use them. They will probably help but to what degree is unknown.
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post #15 of 27 Old 12-10-2019, 08:58 AM
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@Thomas_Z

As a side note, there are what we call the big box stores such as Lowes and Home Depot. Us old timers do not consider them as legitimate lumber yards. If you want quality lumber for furniture, you will have to find a hardwood lumber yard.

If you go back to your profile, add the town you live in as your location. it will appear on here with your posts and we will be better able to assist in things like this if we know where you live. There will be other questions you will ask such as where to get furniture grade lumber, hardware, etc.

BTW, Welcome to the forum
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post #16 of 27 Old 12-10-2019, 09:40 AM
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Can't find any topics related to the lumber drying process... I am new to woodworking, and can't understand if I need a couple of dehumidifiers and a fans for that. Only know I need a moisture meter...
How do you know that you need a moisture meter? Most of the woodworkers I know have gone their entire lives without one. I do not own one.

-> Before you buy anything, including a moisture meter, tell us more about the kind of wood you will be working with and the kind of woodworking you would like to do with it. It might help if you share the area where you live, too.

From your post, I assume that you have some green (fresh) wood that needs to be dried. It would help if you share more details so that others can give you better advice. There is more to processing freshly cut wood than just drying. Sealing the ends is but one example. Dealing with insects is another.

Imagine if someone had asked about the "wood cutting process" in their first post without providing any other information. What would you tell them?
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post #17 of 27 Old 12-10-2019, 10:48 AM
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How do you know that you need a moisture meter? Most of the woodworkers I know have gone their entire lives without one. I do not own one..........................
Neither do I.
Again, it has to do with dealing with reputable hardwood lumber yards.

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post #18 of 27 Old 12-10-2019, 11:01 AM
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Purchasing Hardwoods

One more thing...............when you buy hardwoods they do not come in standard dimensions like 2X4's or 2X8'sor any set size.
Hardwood is purchased by the board foot and comes in random lengths and widths - just like it came from the lumber mill. It is more or less a slab. It has rough surface and rough edges. You can have them plane it and straighten one edge or you can do it yourself at home. They charge extra for that. My commercial shops always had planers and rippers but I always had the lumber supplier do it mainly because it was not cost effective to do it myself. Working in your home shop it would pay to do it yourself once you acquire the equipment - mainly a planer. A straight line rip jig is easy enough to make yourself

A board foot is the equivalent to 12" x 12" X 1". So when you pick out a piece, they will measure for you, or you can measure yourself and do the calculations. Most places sell the slab and wont cut you just a small piece. You have to buy the whole board. On the brighter side, they have a scrap area where you might be lucky enough to find exactly what you want.

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post #19 of 27 Old 12-10-2019, 11:08 AM
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12-14% is the number for air dried wood where I live.


Acclimation to the environment it going to live is really the objective. For example, wood acclimated to an open air shop in a fairly humid environment & will live in a climate controlled house will shrink considerably.



The wood you have there sounds ready to live in your shop, but I recommend sticker it for a week or two in the shop just to let it totally acclimate.
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post #20 of 27 Old 12-11-2019, 12:35 AM
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I was going to work with red oak and the idea was to store it in the attic with dehumidifier and fan placed withing, periodically monitoring the humidity. That won't be outside storage or something like that to be worried about the wood origin. You, however, suggest me to purchase lumber from lumber yards for start, right?
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