Ash and Cherry are considered, dry on the stump, so, yes, with a old stove, it can be burnt in a short matter of time, now, nope. And all wood depends on when it was dropped, dormant?, Sweet, spring, aw the sap is running, it takes longer to dry
Ash or willow?
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Ashful
Minister of Fire
Ash is one of the wettest woods I encounter when green, I've had trees literally gush like a garden hose, if left more than a minute between face cut and back cut. It is most definitely not good to burn green in any stove trying to achieve secondary burn (i.e. modern non-cat or catalytic).
But having said that, it gives up its moisture faster than most hardwoods, and can be ready to go after just one summer in sun and wind.
As to why it's measuring less than 1 M-ohm, no idea, never tried manually checking the resistance on any of my wood. Handheld moisture meters approximate moisture content by resistance, but they have a fixed distance between probes, which are designed to penetrate wood better than your typical DMM probes, and the current injection may be set at a different level than your DMM when set in mega-ohm range (which would typically be only micro-amps to tens of nano-amps).
Yeah not so much that it's measuring less than 1 Mohm but the specified 20% moisture mark on the list states 20% or less moisture starts at less than 1 Mohm. Most others start at 2-4 Mohms.
![[Hearth.com] Ash or willow?](https://www.hearth.com/talk/data/attachments/300/300007-0565a07fb3e6a53eb43f361a96ece784.jpg?hash=JACrCKIiJK "[Hearth.com] Ash or willow?")
My ash are all dying from EAB, but usually a fresh cut ash is upper 20s to lower 30s as far as moisture. With some limb wood being under 20%.
Back before EAB I definitely saw some juicy ash. But back then I didn’t have a moisture meter.
I think the wettest tree I’ve seen was a poplar (big tooth aspen).
Back before EAB I definitely saw some juicy ash. But back then I didn’t have a moisture meter.
I think the wettest tree I’ve seen was a poplar (big tooth aspen).
Ashful
Minister of Fire
Find a big ash (over 40" DBH), make a face cut, and walk away for 20 - 30 minutes. When you come back, you will see.
The tree below was one of these cases. It was forked too high to cut the two trunks individually, so I made the face cut below where they joined. It became obvious it was going to come apart during the back cut (you can see the crack thru the trunk, perpendicular to my hinge), so I took a break to arrange a strap between the trunks, to help ensure that it wouldn't prematurely come apart on me.
During the 20 - 30 minutes it took me to arrange the strap, it started gushing. Thought it was the strangest thing, until I had a second one do the same thing to me, a year later. Both trees were large (over 40" diameter), and both seemingly dying of something other than EAB, as this was before EAB was known to our area.
![[Hearth.com] Ash or willow?](https://www.hearth.com/talk/data/attachments/300/300022-be2e50e8ee817326b9307456ad65f4ad.jpg?hash=zy4ekM39Bx "[Hearth.com] Ash or willow?")
Ashful
Minister of Fire
Interesting. I'm not a chemist, but I guess that the resistance is based on a combination of factors, including salts and other minerals in the wood, more than water content.
My only exposure to this is gun stocks and axe handles, certain species of which cause the surrounding metal to rust badly. One reason you'll never see an oak axe handle, unless made by an unknowing amateur.
Ashful
Minister of Fire
That property has a lot of big trees, and it's where I did nearly all of my cutting for 10 years. The guy in the photo is my old cutting partner and property owner, recently deceased, and I use to leave him all the smaller stuff that was easier to lift. That meant I was dragging home all of that 4-foot crap.
Big wood is fun to drop, and fun to look at in photos, but hell to move the rounds and split.
i have a set off directions for a multimeter from the internet. below 3 meg season more. above 3 meg ok. with the leads 1 1/4 inches apart.
i have had wood gush water when splitting by hand with a moll but it was poplar. everytime i hit it water would gush out like i hit a puddle. the tree fell in a customers driveway and they offered it to me. it was in good shape no rot but heavy when green and light in weight when dry
Are you guys just using a regular DMM, or a megohm meter? I wonder how the results would be using a megohm meter on the 500v setting. If it would be a better test than just using a regular DMM...
At 500 V you may be near the breakdown field of wood? The resistance measured would likely be lower, so mc deduced higher.
Other than the input impedance of the meter being better, I don't think there is anything to be gained by doing that because the wood won't be ohmic up to those voltages. So it would require a whole new calibration.
Other than the input impedance of the meter being better, I don't think there is anything to be gained by doing that because the wood won't be ohmic up to those voltages. So it would require a whole new calibration.
Yeah but thats just a huge generalization. If you look at the measurements for 20%, ash is at 60-90 Mohms. Oak is from 1.15 Mohms-2.1 Mohms (white/red). Birch is high at 2-3.5 Mohms. It's quite a range. At least with thw species I deal with in my area.
Ashful
Minister of Fire
This is an unusual crossing of my hobby and profession, I spend several hours per week calculating ionization breakdown voltages and fields in high power electronics, but have never come across ash or willow in industrial electronics.
Breakdown in air at 1.25" would be roughly 94,000 volts, so no concern with 500 volts there. How that reacts with wet wood would only be a guess on my part, but I do think there's potential for current flow to give a flawed reading by actually changing the conductivity you are trying to measure. If you're measuring megaohms, you don't need much current to cause sufficient voltage to get an accurate reading, so I think you'd be much better off with a DMM. But again, just a semi-educated guess.
We're measuring firewood. It's not a huge deal, is it? I mean most just use common sense, mother nature and weight and sound to tell if wood is dry or not. These mm are just ballpark measurements and I think being within those ranges can give a good indication but I highly doubt you need a megger to measure the resistance of your wood pile. Lol.This is an unusual crossing of my hobby and profession, I spend several hours per week calculating ionization breakdown voltages and fields in high power electronics, but have never come across ash or willow in industrial electronics.
Breakdown in air at 1.25" would be roughly 94,000 volts, so no concern with 500 volts there. How that reacts with wet wood would only be a guess on my part, but I do think there's potential for current flow to give a flawed reading by actually changing the conductivity you are trying to measure. If you're measuring megaohms, you don't need much current to cause sufficient voltage to get an accurate reading, so I think you'd be much better off with a DMM. But again, just a semi-educated guess.
I'm glad I got my mm. It's fun to use and interesting but I bet some would argue that they're unnecessary.
the point is that wood splits are not homogeneous, as air is.This is an unusual crossing of my hobby and profession, I spend several hours per week calculating ionization breakdown voltages and fields in high power electronics, but have never come across ash or willow in industrial electronics.
Breakdown in air at 1.25" would be roughly 94,000 volts, so no concern with 500 volts there. How that reacts with wet wood would only be a guess on my part, but I do think there's potential for current flow to give a flawed reading by actually changing the conductivity you are trying to measure. If you're measuring megaohms, you don't need much current to cause sufficient voltage to get an accurate reading, so I think you'd be much better off with a DMM. But again, just a semi-educated guess.
Fibers, channels of fluid (with salts). That will severely limit the voltage wood can withstand.
It may not at all be near breakdown, but it's closer. And how that looks like in an I(V) curve is that it's steeper - and that was my main point. The resistance you measure will be lower, and so the higher the voltage (and I do think 500 V in wood is going to be beyond the ohmic approximation around zero bias), the lower the mc indicated by the measurement - which would be incorrect info to base any conclusions on.
I have not fired up the Keithly 2400 to measure the I(V) of a split though...
Ashful
Minister of Fire
Agreed. I haven't even used my moisture meter in about ten years. Cut it, split, it, stack it, wait 2 - 3 years, then use it. At this point, I can tell if a split is too wet to burn, almost as soon as I pick it up.
The moisture meter is useful for any new burner, or anyone dealing with an EPA stove for the first time, until they get a system and a feel for things. After that, I suspect most never use it again.
getting a megger or as we say in mass ( a megga ) is around a $1000.00 dollars give or take a moisture meter is about $25.00 give or take so using a little common sense =___________ i use the pick it up and if it's light it's good to go. i have a moisture meter and rarely use it.
Lol. Yes it’s interesting to think about testing firewood with a megger, but probably doesn’t make much sense unless you already have one.
I love data, so using a moisture meter is kind of fun for me. Kind of like using an LCR meter to match my caps and coils when building a speaker crossover. Will you hear the difference between the speaker with the 4.67uf and the 4.73uf cap? Probably not. Is it fun to match them up the best you can? To me, yes
Will I keep using the moisture meter for years to come? Probably. Can I tell the difference between wet and dry firewood? Definitely
I tested my 13$ HF moisture meter against a 34$ MMD4E meter, and the HF meter works good enough. As my dad would say “it’s good enough for who it’s for”.
I love data, so using a moisture meter is kind of fun for me. Kind of like using an LCR meter to match my caps and coils when building a speaker crossover. Will you hear the difference between the speaker with the 4.67uf and the 4.73uf cap? Probably not. Is it fun to match them up the best you can? To me, yes
Will I keep using the moisture meter for years to come? Probably. Can I tell the difference between wet and dry firewood? Definitely
I tested my 13$ HF moisture meter against a 34$ MMD4E meter, and the HF meter works good enough. As my dad would say “it’s good enough for who it’s for”.
I'm still in my first year so I need a moisture meter, especially since I heat 100% with wood. Since I had my install last December, finding dry wood was tough. I did find some. I then started to do the right things. I bought 6 cords cs and stacked them in the sun for 6 months. Over half is tested and now stacked inside my shed for use this winter. Now I'll buy my wood this fall and leave it out for a full year. Hopefully I have some leftovers so the cycle just gets longer each successive year. I can only do what I can do.Lol. Yes it’s interesting to think about testing firewood with a megger, but probably doesn’t make much sense unless you already have one.
I love data, so using a moisture meter is kind of fun for me. Kind of like using an LCR meter to match my caps and coils when building a speaker crossover. Will you hear the difference between the speaker with the 4.67uf and the 4.73uf cap? Probably not. Is it fun to match them up the best you can? To me, yes
Will I keep using the moisture meter for years to come? Probably. Can I tell the difference between wet and dry firewood? Definitely
I tested my 13$ HF moisture meter against a 34$ MMD4E meter, and the HF meter works good enough. As my dad would say “it’s good enough for who it’s for”.
The main thing is wood is fun! I love everything about it including my mm.
I love cutting, splitting, stacking firewood - for about 1 - 2 hours. Then I really wish I could harness some sort of jedi powers to automagically cut and stack cords. I have enough now at a weekend / summer camp, that I hope I wont be cutting/splitting for another 2 years. I do have alot of rounds on my property that I need to pickup, split and stack. Some are hard to get to, and my tractor crapped itself. So my goal is to get that working again so I can haul this stuff out, and also use it as a plow for snow. Otherwise, I do what I did last year, just run over it a dozen or so times until I can walk on it without sinking a foot or two.
Ashful
Minister of Fire
That's a big part of it for me, too. I like saving money, although with what I've spent on stoves, chimneys, sheds, and wood processing equipment, the actual dollars saved is really dependent on how creative I get with the accounting. If I didn't enjoy sitting by a stove, or the process of harvesting that wood, it would be tough to find the motivation or justification for all this work.
You've probably already read this, but always worth repeating for others, on getting reliable moisture meter readings:
1. You must always test on a fresh split face of wood. Testing the outside of wood that has been split more than a day or two will give false low readings. Split a piece down the middle to test the internal MC%
2. Do not test on end grain, it must be side grain, although orientation of probes with or perpendicular to the grain is not important.
3. Wood must be near 70F to use the meter reading directly, unless you have a meter that a can compensate for outdoor temperature. Alternatively, you can Google for temperature correction tables, which will allow you to convert the reading you see at a given temperature to actual MC%.
4. Probes must be pushed firmly into the wood, as far as possible without breaking them. This is easy for softwood burners, but with oak, hickory, locust... just do what you can.
5. Best to test three places on that fresh split face, and average the numbers, to get an accurate reading for that piece. Repeat on a few pieces from different places in your stack, to get a good average for the stack.
Have you done the experiment regarding the orientation of the pins?
I always thought (that I remembered) that the manual said to put the pins in along the grain. That would make sense as in principle wood is anisotropic. So the calibration would be valid only in one direction.
But I have not checked how large the difference is, and thus whether it matters.
I always thought (that I remembered) that the manual said to put the pins in along the grain. That would make sense as in principle wood is anisotropic. So the calibration would be valid only in one direction.
But I have not checked how large the difference is, and thus whether it matters.
