# Moisture content in fire wood



## Brandon3r (Oct 11, 2014)

So I went to Lowes today and bought a moisture meter and checked my wood that's been cut and split since late winter early spring and it tested in the mid to high teens. It has been raining here almost every day for more than a week so I'm sure that hasn't helped me any, what does everyone look for in moisture content in their wood?


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## tarzan (Oct 11, 2014)

Mid to high teens some here will say lower but you should be just fine providing you are reading on the fresh face of resplit pieces.


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## Rossco (Oct 11, 2014)

Under 20% is usually good to go.


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## tigeroak (Oct 11, 2014)

Never tested mine . After 3-5 years drying in racks it is ready. But I am 5 years ahead. Building 2 more 4x5x16 foot racks this fall.


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## solarguy2003 (Oct 11, 2014)

In my old stack with tarps and so on, it would never go below 14-15%.

In my new magic greenhouse/wood drier, it easily goes below 3%.  Here's the thread if you're curious:

https://www.hearth.com/talk/threads...to-store-and-dry-wood-working-awesome.129149/


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## Seanm (Oct 11, 2014)

Some here will say there is no need for a moisture meter and that is true if you have the space to dry your stacks for 2 to 3 years. For the rest of us who don't have an acreage they are a valuable tool and a fun toy. My opinion which is mine alone is that its best to be 10 to 20%. Any more and my stove seems to be kinda sluggish. If you can get a wood species calibration chart for your meter that would be helpful. A recent thread here enlightened me to the fact that the readings im seeing on my lodgepole pine might not be accurate and I may have to use some adjustments. Ive sent two emails to the company that produced my meter asking them to produce a calibration chart and haven't heard back.


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## Lumber-Jack (Oct 12, 2014)

Seanm said:


> Some here will say there is no need for a moisture meter and that is true if you have the space to dry your stacks for 2 to 3 years. For the rest of us who don't have an acreage they are a valuable tool and a fun toy. My opinion which is mine alone is that its best to be 10 to 20%. Any more and my stove seems to be kinda sluggish. If you can get a wood species calibration chart for your meter that would be helpful. *A recent thread here enlightened me to the fact that the readings im seeing on my lodgepole pine might not be accurate and I may have to use some adjustments.* Ive sent two emails to the company that produced my meter asking them to produce a calibration chart and haven't heard back.


I'm curious Sean, what adjustments you feel you need to make? Is your lodgepole not burning well for you? 
Even if the moisture content reading of lodgepole do need to be adjusted slightly higher for an accurate approximation of it's "true" MC, I've still found that anything under 20% on my moisture meter still burns adequately enough, and since 99.9% of my lodgepole reads in the low teens, and it's only the odd round from the base of the tree that ever reads close to 20%, and even that stuff seems to burn fine, I've never really worried too much about the theoretical need to adjust my reading for lodgepole.
I still stand by the rule that anything under 20% is good to go. And as you are likely aware, usually the very base of the trees contain the highest MC, so if the base of the tree is 20% or less, then for sure the rest of the tree is well under that.
Still, sometimes when I'm splitting my lodgepole I encounter rounds that seem heavier than the others and I get a little paranoid so I'll stop and grab my moisture meter and take a reading on a fresh split. I'm always pleasantly surprised to see that it reads in the low teens like the rest of it.


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## Seanm (Oct 12, 2014)

> I'm curious Sean, what adjustments you feel you need to make? Is your lodgepole not burning well for you?


 its just that I'm curious what the mc of the wood is. It bugs me to think that when I'm reading 18% on my meter that it could actually be 23% Either way I'm good with it but I tend to split hairs when it comes to my hobbies! I haven't checked it since split but all my stacks whether its lodgepole, larch or fir was reading under 21% and lots of it was quite a bit lower when it was split in May-September. The lodgepole has been burning quite well. I love the tree, it burns hot and clean so no problem there. I had some Larch that was reading around 23% that I tried burning a couple of years ago and found compared to my splits that were less mc it just didn't burn well. I'm surprised that its been suggested that wood is ok to burn above 20% but i guess results can vary with different kinds of stoves and wood.[/quote]


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## Seanm (Oct 12, 2014)

I wonder why my post and reply to lumber jack above came through as a quote? Happy thanksgiving Hearth members!


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## BrotherBart (Oct 12, 2014)

Mangled the quote opening tag when you trimmed the replied to quote.


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## Seanm (Oct 12, 2014)

BrotherBart said:


> Mangled the quote opening tag when you trimmed the replied to quote.


Thanks for fixing it!


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## Cory S (Oct 13, 2014)

I find 8-16% works best for me.  The dryer it is, the less air it needs to burn.  Last 2 weeks, I've been burning wood that is at about 5-8%.  Burns clean clean clean, and hot hot hot.  The outgassing is beautiful, and I can burn with the air control just about all the way closed.   Stove top temperature hovers in the 450-650* range for 5-6 hours.


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## red oak (Oct 13, 2014)

Cory S said:


> I find 8-16% works best for me.  The dryer it is, the less air it needs to burn.  Last 2 weeks, I've been burning wood that is at about 5-8%.  Burns clean clean clean, and hot hot hot.  The outgassing is beautiful, and I can burn with the air control just about all the way closed.   Stove top temperature hovers in the 450-650* range for 5-6 hours.



Just curious  - where/how do you get wood that is 5% moisture content?


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## BrotherBart (Oct 13, 2014)

Cory S said:


> Last 2 weeks, I've been burning wood that is at about 5-8%.



Not on planet Earth you haven't.


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## Rickb (Oct 13, 2014)

I have only enough room for 1 year.  so I burn anything under 22%.  Mostly ash and silver maple but a little cherry mixed in.

I also burn a lot of building scrap.  Which is pine lumber and its at 12-15% so I would love to see 5%


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## Cory S (Oct 14, 2014)

BrotherBart said:


> Not on planet Earth you haven't.


 
So I checked that batch again, and my meter was not on the correct mode setting.  Correct setting was showing 8-13% when I rechecked this morning.

This is wood that has been inside for over 2 years.  We try keep the RH at 45-55% in the home year round.


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## Applesister (Oct 14, 2014)

Testing oak splits from different parts of a stack, the old fashioned way.


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## dafattkidd (Oct 14, 2014)

Cory S said:


> So I checked that batch again, and my meter was not on the correct mode setting.  Correct setting was showing 8-13% when I rechecked this morning.
> 
> This is wood that has been inside for over 2 years.  We try keep the RH at 45-55% in the home year round.


Cory, I'm sure that wood is great to burn, but you aren't getting a good reading like that. The best way to get an accurate reading is to split a piece of firewood and stick the prongs in the center of the fresh split. Not on the end.


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## Cory S (Oct 14, 2014)

dafattkidd said:


> Cory, I'm sure that wood is great to burn, but you aren't getting a good reading like that. The best way to get an accurate reading is to split a piece of firewood and stick the prongs in the center of the fresh split. Not on the end.
> 
> 
> 
> ...


 
I do that with my newer wood.  When I split the old stuff and check it, it comes out within 1% of the splits I check on the ends   This wood is 100% acclimated throughout.  Also, if I get the prongs in deep enough, I do not get any variance in % even on fresh splits. (Maybe 1% again)..


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## FTG-05 (Oct 15, 2014)

tigeroak said:


> Never tested mine . After 3-5 years drying in racks it is ready. But I am 5 years ahead. *Building 2 more 4x5x16 foot racks this fall*.



Pics or it didn't happen!


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## Poindexter (Oct 17, 2014)

On my old non-cat EPA stove anything under 20% was good, lower was better.  On the old smoke dragon that belonged to my grandpa out in my shop, anything under 20% is good, lower is better.

I have my first ever catalytic stove this season, we had it installed in May.  The book on it says 13% MC per electronic gizmo, maximum.  Last year's models from the same manufacturer, the books for those all said 16% per electronic gizmo, max.  My cat stove seems to run good on 16%, but lower is once again better.  For the last two weeks or so we have been seeing mid +30s dF for a few hours at midday, pretty much below freezing 22 hours a day for a couple weeks.  Over night lows get to the single digits about half the time.  Seems like the colder it gets the more I like my combustor equipped stove.


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## Kevin Dolan (Oct 17, 2014)

solarguy2003 said:


> In my old stack with tarps and so on, it would never go below 14-15%.
> 
> In my new magic greenhouse/wood drier, it easily goes below 3%.  Here's the thread if you're curious:
> 
> https://www.hearth.com/talk/threads...to-store-and-dry-wood-working-awesome.129149/


Solar guy at 3% my wood would self combust! check your moisture meter lol!!


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## solarguy2003 (Oct 17, 2014)

I did. I calibrated it using the weigh/bake/weigh/bake/weigh  method.  Surprisingly accurate for a cheap chinese thing.

I know you're kidding, but spontaneous combustion requires the fuel to undergo pyrolysis first, the exception being oil soaked cotton, especially linseed oil, or some of the other 'drying' oils.

I got accidentally interested in spontaneous combustion when I was studying polymer chemistry.

My firewood does light very nicely though.


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## Sprinter (Oct 17, 2014)

It's not rocket science.  Just open a fresh split, stick the pins in the fresh face and aim for around 20%.  Most meters are plenty accurate for firewood and anything less the maybe 25% at the higher end is fine.  20% is what most EPA stoves are designed around.


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## Kevin Dolan (Oct 17, 2014)

solarguy2003 said:


> I did. I calibrated it using the weigh/bake/weigh/bake/weigh  method.  Surprisingly accurate for a cheap chinese thing.
> 
> I know you're kidding, but spontaneous combustion requires the fuel to undergo pyrolysis first, the exception being oil soaked cotton, especially linseed oil, or some of the other 'drying' oils.
> 
> ...


Solar guy yes joking, but if your wood is below 20% moisture you are in good shape to burn. We get combustion in our hay and silage when it is not dried enough before storing , it is strange chemistry but oh well!!


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## solarguy2003 (Oct 18, 2014)

Yeah, wet hay, that's another strange exception that is driven by microbial growth.


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## Kevin Dolan (Oct 18, 2014)

solarguy2003 said:


> Yeah, wet hay, that's another strange exception that is driven by microbial growth.


Yes so what is wood drying, what takes the moisture out of the wood?
Silage involves fermentation what is wood doing drying?


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## solarguy2003 (Oct 18, 2014)

Wood drying is all about relative humidity/temperature and air movement.


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## Kevin Dolan (Oct 19, 2014)

solarguy2003 said:


> Wood drying is all about relative humidity/temperature and air movement.


Solarguy what is the chemical process of moisture out of the wood, would like to know that,is it sort of like osmosis I in cells exchanging moisture for air??
Humidity,air flow are definelty what dries wood out but would like to know the chemistry  if you know that.
I think the wood finds its equilibrium from outside temps and wind but it must find a balance with the souring


solarguy2003 said:


> Wood drying is all about relative humidity/temperature and air movement.


yes solar guy the wood is trying to reach its natural equilibrium once split and stacked. So it is related to where you live with the humidity and air flow, my sense around here is that I can get my wood to around 15- 20 % moisture in two years or slightly less with normal stacking outside, oak excepted. Always learning.


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## McKeznak (Oct 19, 2014)

Kevin Dolan said:


> my sense around here is that I can get my wood to around 15- 20 % moisture in two years or slightly less


Agreed with the humidity in the summer around here I'm not sure I'd ever get below 15% no matter how long it sat out there.


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## Sprinter (Oct 19, 2014)

Here is a study from the Forest Service showing expected equilibrium MC for various locations in the country in different months depending on temp and RH

http://www.fpl.fs.fed.us/documnts/fplrn/fplrn268.pdf


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## Kevin Dolan (Oct 19, 2014)

Sprinter said:


> Here is a study from the Forest Service showing expected equilibrium MC for various locations in the country in different months depending on temp and RH
> 
> http://www.fpl.fs.fed.us/documnts/fplrn/fplrn268.pdf


Sprinter great info what I was looking for , so around 15% is the best I can shoot for here in ontario-works for me.
Thanks for taking the time to post that info.
Kevin


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## McKeznak (Oct 19, 2014)

Great link thanks!


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