Moisture Content Test, 10/29/15 thru 4/29/16 versus 4/29/16 thru 10/29/16

[Longstreet]

I remember reading this when you first posted. I'm subscribed now. I too think winter has decent drying potential as well (low humidity, dry air, high winds), although lacks temperature, there is still plenty of sunshine. As expected, summer is probably king, but I'm looking forward to seeing your results.

In most areas, outdoor winter air doesn't have lower relative humidity than other times of the year. Outdoor relative humidity is pretty consistent throughout the year across most of the country. Indoor air in the winter may have lower relative humidity,, but that's only a result of the heating cycle. It's the exact same principle which make solar kilns work.

Edit: Clarified that I meant relative humidity at all times above.

 

[TedyOH]

I agree, what does get really low around here in the winter is the dew point reading, it was 5% the other day while the humidity was 67%, I thought to myself, yeah right, 67%. But if you google "dew point" and read a few paragraphs, you will see that "Dew point is the true measurement of the atmospheric moisture", so being at 5% the air was quite dry.

More in depth between the 2 and how they work together.

http://www.whio.com/news/news/dew-point-and-humidity-whats-the-difference/nmkLC/

 

[JRHAWK9]

dew point is measured in degrees, not percentage. It's the temperture at which dew forms.

 

[TedyOH]

Thanks was going to edit that.

 

[JRHAWK9]

I pay attention to dew point all the time. more-so in summer, as I HATE humidity....so anything over a 60° dew point or so is humid for me. Anything over a 70° dew point and I may as well be sitting in a sauna...lol

 

[Hasufel]

Outdoor relative humidity is pretty consistent throughout the year across most of the country.

There's a handy chart where people can look this up for their own region. In most places the temperature is a larger factor because the water-carrying capacity of air increases rapidly with temperature. Air at 30C/86F can hold about 30 times more water than air at -20C/-4F.

 

[TedyOH]

OK - I'll be out of town on the 30th so I tested the wood a couple days early, the 56% MC piece is the split I removed from the vacuum packing today.
Started at 53% MC on 10/27/15 - split the split today, 6 months later on 4/27/16 right on the "year 1" growth ring, took both end readings and center reading, averages out to 40% MC, not as low as I expected (25% guess in Oct.) but it was a damp wet winter and little to no sub zero weather.



I also re-split one of the splits and the average was 32%, closer to my 25% guess and this split before it was re-split would be more to the actual size I would burn so I'm taking 32% as my test results. The original piece was about 4" x 8",kinda big for my insert.

So the facts are this, a Large Ash split stacked on my property during the 6 months of winter looses quite a bit of moisture. Wood dries in the winter.




I'm looking forward to the end of October and the results - will it be below 20%? We will see!

 

[Poindexter]

Wood dries in the winter.

Yup. Nice going and thank you. And if you can cover your stacks someway to get even 10 degrees of thermal gain it will dry a lot more, warm air can carry more water than cold air.

 

[TedyOH]

Well today would be the day to test the piece of ash that dried for the 6 hotter months.......even though we had 35 days of 90+ degrees temps this summer, I'm going to let the split sit in the laundry room for 24 hours to dry out a tad, it's been blowing rain for 48 hours.....going to let some of the surface moisture evaporate so I will split tomorrow and post the average MC%

 

[Woody Stover]

today would be the day to test the piece of ash that dried for the 6 hotter months

I assume the weather there was similar to here. Plenty of pretty warm days, but rain almost every day for months had to slow drying somewhat, I'd think...

 

[TedyOH]

Not a lot of rain at all really, been lucky.....

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[Poindexter]

What was your RH with the 90 degree temps?

I pasted an emc table into my kiln operation thread. iirc +90s dF @ 90% RH gives an emc just under 20%

 

[Woody Stover]

What was your RH with the 90 degree temps?
I pasted an emc table into my kiln operation thread. iirc +90s dF @ 90% RH gives an emc just under 20%

In the middle of the afternoon when RH was at its lowest, it would still be 50-60%. At night it would be upper 90% range. Yuck.

 

[TedyOH]

So summer wins.......wins by "twice" as much........the 6 month summer ash is at 20% where the 6 month winter ash was at 40% (both started at 53% MC)...still in my mind c/s/s in fall and winter is worth it as drying does occur........good news is all my ash is at or under 20% and it happened in 12 months, smaller splits were reading 15-17%. I'd be curious to try this with white or red oak but they just dont blow over around here,

 

[Woody Stover]

still in my mind c/s/s in fall and winter is worth it as drying does occur........good news is all my ash is at or under 20% and it happened in 12 months, smaller splits were reading 15-17%. I'd be curious to try this with white or red oak but they just dont blow over around here

That's my theory, too. Even though it's winter, the initial moisture, which is the easiest to get rid of, will still evaporate. Then you have a running start when the hot weather gets here. From your results it sounds like I'll be able to get the White Ash I'm grabbing now dry for my SILs by next season, in case they need it. It will be stacked 3 rows wide on a pallet. I guess if it's hot and dry, that shouldn't hurt the drying rate too much. It is dead-standing, MC mid-30s lower in the trunk.
It's interesting that although we don't live too far apart, the differences in the woods are pronounced. Here, the Red Oaks will rot in the center sometimes, then blow over or snap off. I have 8 or 10 trees either standing dead or down, and the vast majority are Red or Black Oak. I need to get that stuff up, because I'll have my hands full when the EAB gets here.
But yeah, the White Oaks seem very durable. They don't seem to die from disease or get blown over very often. I got one blow-down a few years ago, then I got another small one (10-12") recently....when the ground was saturated and a Red Oak blew over and took out the White on the way down.
In another drying test, I think you would have to split Red Oak pretty small to get it dry enough in one season...smaller than would be usable in the stove. I think medium-small Red Oak can make it in two years here.

 

[TedyOH]

I should mention my ash was stacked "log cabin" style, a cord of so of it....I'm sure that helped. There are huge red oaks in the woods here....did some circumference measurements a while back, measured 4.5 foot from the ground and they're about 5.5 foot in diameter...biggest trees back there that refuse to come down in the wind or lightning. I did cut a huge pin oak 2 summers ago in the yard, it died for some reason, and fortunately got it to 17% in 18 months (2 summers of drying), about 3 cord so with that, the ash, and some misc. stuff I'm good for the winter for sure.

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[St. Coemgen]

So summer wins.......wins by "twice" as much........the 6 month summer ash is at 20% where the 6 month winter ash was at 40% (both started at 53% MC)...still in my mind c/s/s in fall and winter is worth it as drying does occur.

My conclusion from your results (if I read them right... it is somewhat difficult to follow your methods as written) is that, while some drying does occur in Winter, since both the split you kept in vacuum pack (the six month split) and the split you left out all winter (the 1 year split) reached the same moisture content (MC) in one year, the actual value of winter drying is irrelevant. That is, Ash appears to dry to about 20 percent MC in 1 full year (winter and summer), or in 6 summer months. So cutting and stacking in Fall or in Spring gives the same results and there is no benefit to one method over the other.

In other words, does winter drying occur? Of course. But you have too few data points on measuring MC to really say winter drying is of any real value for drying wood in six months versus one year to 20% MC. For example, if you sampled MC weekly, you might have seen the 6 month split MC quickly reach that of the 1 year split in a few short weeks in the spring (since that external moisture is the most easy to loose), then both slowly loosing the rest of the internal moisture at an equal pace during the summer. Or, as an other example, maybe the 1 year split stabilized at 20% MC in July, but the 6 months split took until later August to reach 20% MC. That would be good information to know, but the current resolution of measures can not provide this fine grain level of data. You did a nice pilot study, but like such pilot studies they tend to generate more questions than they answer. I would recommend more frequent measurements next time from Spring onward to really answer such questions.

But even so, and actually, this is very good information to know and of value for planning our wood stacking and cutting, since I can then not feel guilty if I do not cut and stack in the fall; I can wait till spring.

So overall, kudos for your study. I hope my comments help you improve your experimental design for any future, similar tests you would like to perform.

 

[TedyOH]

I took 2 equal splits on 10/30/15, put one immediately in the stacks for 6 winter months, vacuum packed the other one, 6 months later on 4/27/16, I split the piece and the moisture dropped to 40% (from 53%), on 4/27/16 the vacuum packed piece went to the stacks and yesterday, 6 months later, it was split and went from 53% to 20%. Point being, split some ash today and in 6 months it will be dryer.
I see what you mean about 6 months vs a year being equal or getting to the same number.....but as I mentioned small splits from the same tree that were stacked log cabin style for a year were at 16% on average.
So if dealing with ash, sure wait until Spring, if it's oak, I'd get busy today.

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[jatoxico]

In other words, does winter drying occur? Of course. But you have too few data points on measuring MC to really say winter drying is of any real value for drying wood in six months versus one year to 20% MC.

Yes, TedyOH's results agree with published forestry data going back many years. Comparing the similarly sized splits, the fall/winter dried split lost just under 25% of the available moisture while the spring/summer split lost about 63%. Had his winter been colder the result would have been more drastic as the winter would have been >40%. The extracellular moisture (25%) that was lost from the winter split would be lost very quickly in warmer weather so no real advantage.

So IMO split and stack when you can but there's no reason to fret if you can't get your wood CSS in the fall.

 

[Poindexter]

A couple points as a winter time splitter and stacker.

I know my wood dries "some" further in winter weather. I also have never seen a piece of wood get from too wet to burn to dry enough to burn during winter (below freezing) weather.

There are three primary reasons I split and stack during winter.

1. No mosquitoes, no snakes, no heat stroke, no mud getting on the splits.

2. In the summer months I would rather be fishing or boating or hiking or hunting. Or sitting in a chair out in the sun with a good book and an ice cold Gin and Tonic.

3. Splitting is my wintertime outdoor activity. When I get cold, I just come into the garage for a few minutes, it's usually my fingers or toes. Stand next to the hot water heater, stamp my feet a few times, minimized risk of frostbite. I could be lying on the couch getting fat...

One thing I wonder about is the advice in the BK manuals that wood should be "split and stacked for two years" for every model in their line I have looked up. It seems to me summer time splitters aren't getting a full summer worth of seasoning that first year if they wait for the snow to melt before they start splitting. As written, the summer time splitters are getting 1.x summers of seasoning if they season two years, but only 0.x summers of seasoning if they split in spring and burn in fall.

When I have all my fresh wood split and stacked on Saint Patrick's Day, I am getting 1.0 summer's worth of seasoning that first year.

One concept I find really useful is to know the FSP (Fiber Saturation Point) of the wood in my stacks. For my local birches and spruces FSP is pretty close to 30% MC for every possible species. I have no idea what the FSP is for ash.

Green splits will stay stacked just as neatly as I stacked them until they dry down to FSP. Above FSP splits don't change shape or size at all. Once they cross below FSP, the radial and tangential shrinkage starts, that's when my stacks start leaning and tipping and sagging.

I love it when my stacks start to sag and tip in mid-May, it means I have plenty of summer left to finish drying what I have before it's time to light the stove again.

Nice work @TedyOH .

 

[Hasufel]

There are three primary reasons I split and stack during winter.

1. No mosquitoes, no snakes, no heat stroke, no mud getting on the splits.

2. In the summer months I would rather be fishing or boating or hiking or hunting. Or sitting in a chair out in the sun with a good book and an ice cold Gin and Tonic.

3. Splitting is my wintertime outdoor activity. When I get cold, I just come into the garage for a few minutes, it's usually my fingers or toes. Stand next to the hot water heater, stamp my feet a few times, minimized risk of frostbite. I could be lying on the couch getting fat...

Amen to that. All three.

I know my wood dries "some" further in winter weather. I also have never seen a piece of wood get from too wet to burn to dry enough to burn during winter (below freezing) weather.

I've had good luck with wintertime drying, but my situation is a bit different than yours. Winters here can feature long stretches of dry and sometimes mild weather. But perhaps more importantly, my stacks are under deciduous trees so they get much more sun and wind during winter. Wood can dry surprisingly fast on a cold day when it's sitting in the sun and the dew point is way down in the teens.