Firewood seasonoing. Red oak

[doctorb]

RESULTS:  OAK DRYING EXPERIMENT

After 18 months, I tested the split Chestnut Oak for % H2O to see if the location of the split log effected the %H2O.  Complete description of the set up earlier in this thread.  The logs to be tested have not been moved or protected in any way during that time.

Pic of my outside wood stack with shed in background.  Note log with yellow paint and large washer.  A second experimental log lies directly behind the one in view.  These two logs are labeled "Outside Exposed #1 and #2".



 



 


A third log is buried into the stack outside.  It is labeled "Outside Log Buried".  Note the yellow paint and washer.



 


Similarly, 3 logs were placed inside the shed, with no sun or rain exposure.  Two were placed on top of the stack and are labeled "Inside Exposed #1 and # 2".  Washers denote logs in question.



 


A third log was placed inside the shed and buried within the stack, labeled "Inside Log Buried".



 

All logs were split today and the moisture content measured.  Multiple measurements were taken, all at the midway point of the length and the width of the split piece to attempt to locate the portion of wood furthest from any surface.



 

% H2O

Outside:
          Exposed #1                            10.6 - 12.1
          Exposed #2                            13.9 – 16.8

          Buried:                                    16.4 – 19.2

Inside:
          Exposed #1                            14.2 – 16.8
          Exposed #2                            11.9 – 13.2

          Buried:                                    16.9 – 18.9



As can be seen, all logs were seasoned below the 20% threshold, making them excellent firewood.  Those logs that were exposed, either inside or outside, dried the best.  As it's impossible to put all of your firewood in this optimum location, it is encouraging that those logs buried within the stacks seasoned very adequately as well.  With this very small sample of measurements, it is difficult to make any conclusions regarding the positive or negative effects of being outside exposed to the weather versus under cover in a shed.

As with many experiments, once ended, you clearly see what you should have done to improve the conclusions of the study.  The sample size should have been much larger, permitting measurements at, say, 6 month intervals.  This may shed some light on whether one location would dry faster than the other.  Secondly, my climate may be significantly different than yours.  These logs had significant time to dry, with one winter, one full spring, and two full summers and fall seasons to season.  What may be more important is the variable effect of prolonged winter drying time versus more temperate climates, like mine.

Anyway, it was fun, and your comments and insights are appreciated.

I found the variability of moisture content interesting.  It could be due to the inability to make every piece from the round the exact same size, or possibly from inaccuracies of the testing device or the investigator.

[John Mc]

So how long are you going to keep us on the edge of our seats, waiting for the results?

You experiments seem a lot like the ones I did years ago (I think shortly before you started heating with wood, @doctorb ). Unfortunately, I can no longer find the actual numeric results, but my drying methods since then have been driven by what I learned from it (particularly when I'm behind in my drying and need to shorten the process as much as practical).

In my area, the number of summers of drying is a big factor: 18 months including one summer is quite a bit different than 18 months which happened to include 2 summers. From the timing of your post, I'm guessing you had two summers in your 18 months (though maybe that is not as much of a factor in MD as it is in VT?)

[doctorb]

John-

Thanks for your interest.  I think you must have seen my Results post just as I was placing it online.  It was incomplete for a few minutes as I added stuff to it.  Anyway, your input is always appreciated.

[Andries]

Thank you @doctorb! 
There was a unsplit piece of Burr Oak in my woodstove this am, which was boiling water from the end as the heat from the fire penetrated the wood.
The split oak all around it had started to burn far sooner than the unsplit piece.
So, the lesson for me is to split everything, even the small stuff.
You numbers indicate that covered or uncovered only results in about 3-4% variation. Have to admit, that surprised me.
 So, its good to know what the real difference is, rather than just wondering about it.
Thanks again!

[John Mc]

John-

Thanks for your interest.  I think you must have seen my Results post just as I was placing it online.  It was incomplete for a few minutes as I added stuff to it.  Anyway, your input is always appreciated.

You're right. I just happened to see the few minutes where the results weren't posted

[Old Greenhorn]

fascinating.

[John Mc]

There was a unsplit piece of Burr Oak in my woodstove this am, which was boiling water from the end as the heat from the fire penetrated the wood.
The split oak all around it had started to burn far sooner than the unsplit piece.
So, the lesson for me is to split everything, even the small stuff.

I also make an effort to put at least one split on just about anything I intend to burn. Since I also leave anything under 3-4" diameter in the woods to rot and return nutrients to the forest soil, I don't end up with ridiculously small pieces.

I do tend to split smaller than many people, however. A wood combustion guru friend of mine convinced me that smaller pieces burn more efficiently. (He designed wood combustion control systems for commercial scale wood boilers, and designed a high-efficiency residential wood boiler from the ground up.) That has seemed to be the case - my firewood usage has dropped since I started doing this. It's far from a scientific experiment on my part, since I did not adjust or control for the variation in heating seasons (not to mention the variation from year to year of the species I burn). However, the reading I've done on the subject backs up what my friend recommended.

Your numbers indicate that covered or uncovered only results in about 3-4% variation. Have to admit, that surprised me.
So, its good to know what the real difference is, rather than just wondering about it.
Thanks again!

One thing to keep in mind when evaluating wood drying methods: the first part of the drying process goes relatively quickly: it's relatively quick and easy to dry wood down to the "fiber saturation point" (roughly 30% moisture content, depending on the species). Drying beyond that point takes more time (or more energy, depending how you are drying the wood). As the wood approaches equilibrium moisture content with its surroundings- basically as dry as the wood is going to get given the surrounding relative humidity - the drying process goes slower and slower: air drying from 28% down to 27% goes quite a bit faster than drying from 16% down to 15%. So the gap between wood that "mostly dry" and that which still has some way to go will tend to narrow as the wood approaches equilibrium.

If you have plenty of time, all this means is that eventually all of it will be dry enough to burn. Where it matters is if you are in a rush: the wood in prime location/conditions will be ready, where other pieces will not.

[stavebuyer]

Thanks to Doctor B for the experiment. From the picture the "uncovered stack" is out in the open where it appears to have been exposed to all the elements(sun/wind/rain&snow). 

We a had a "catastrophic" ice storm (4" inches of ice) in 2009. As a result of that storm I had literally decades worth of firewood just cleaning up the yard and woods closest to the house. I cut, piled, and burned brush for several years. There are still some rotting stacks of firewood piled between trees. That process evolved and I burned the wood until I sold the house 6 years later. 

The wood stacked in the "open" fared very well. Six years later all the split wood in the "open" stacks was still in good shape regardless of species(red oak,white oak, hard maple, and hickory) (All my stacks had something under them preventing ground contact.) 

The stacks I had piled in shade starting to rot below the top couple of rows by the second season. The top layers were fine but then the bark followed by the sapwood started rotting in the lower layers. In full shade the lower rows never really dried out and the added rotting bark and sapwood made it progressively worse. As I burned some of the stacks and got more room; I moved and restacked some the deteriorating piles in the sunnier spots and removed the now loose bark etc. As soon as the deteriorating stacks got exposed to full sun and some breeze they dried out and stabilized.

The moral to the story is that split wood in a building will more or less keep until you need it. Split wood stacked out in the open will last a very long time and dry just as quickly. Stacking in shade is a bad plan. Unfortunately I don't have any hard data to quantify. I will add the few rounds I had stacked in the shade without splitting were in poor shape by the 1st winter. The hickory and hard maple were already showing substantial rot, the white oak had rot in the sapwood, and the red oak while sound was still dripping wet.

[doctorb]

stavebuyer.  Good comments.  The shade issue is interesting, as all the wood I had in the shed was always in the shade.  So being stacked outside, where moisture gets onto the wood periodically, AND in the shade has a significant negative effect, in your experience.  
So it's not the shade itself, but the inability for the moisture to be removed adequately once wet that must lead to the rotting and poor seasoning.

I know some folks take the time to crisscross the logs as they stack to maximize surface area air contact.  If you are using a large volume of firewood, this greatly increases the space you need to store it.  This small study shows that wood stacked in the classic side by side fashion dries just fine, given, as John Mc said, enough time.

[John Mc]

That shade comment is similar to what I noticed for stacks left drying in the woods. I'm shade is a contributor, since the stack is cooler than if it were in the sun. Other factors: in general it's cooler in my woods than out in the open. In addition, the restive humidity is higher, and that stack is sheltered from the wind. 

Fast drying requires warmth (sunlight is one contributing factor to that), a relative humidity low enough to draw moisture out of the wood, and air flow to carry the moisture away. Even in a low-humidity environment, still air around the stacks can create a microclimate of high humidity: moisture coming off the wood hangs around, the air nearby gets saturated and the moisture is very slow to dissipate without some breeze to break it up. (Ask kiln operators are well aware.)

[stavebuyer]

My "shaded" stacks were shaded by trees. Wooded area. Very little sun and wind. I will also mention I had some pallets I stacked two rows side by side and some single rows. The double stacks didn't do very well. They tended to stay wet where the inside ends joined. When I ran out of places to stack and scrap lumber to build pallets out of I tossed the rest into one pretty good sized pile. The bottom pieces of the pile in contact with the soil were rotten after about a year. The rest of the pile dried pretty well and closely resembled what had been stacked. I will mention that the "shaded" stuff that I moved and restacked I did  "cross stack" to maximize airflow. 

Something else I noticed was that between bark rotting/slipping, wind, and frost the stacks "moved" more than I ever imagined. Many stacks developed a pretty good lean and several toppled. Trees move when you stack between them, strapped to a pallet the wood shrinks and the straps are loose, and the wood rots if you stack the rows close enough to support one another.


  

[Rick Alger]

Thanks for the test results doctor b