Bad Moisture Meter?

[Simonkenton]

I bought a moisture meter at Lowes a few days ago. Never have had one before.
I got a piece of locust that has been split, and under shelter, for 2 years. I split it and checked it, it read 15 percent.
Well, I am in the humid NC mountains and river fog rolls around my property every night. Though I am sure this wood would have burned pretty well, I doubt it was that low, I would have guessed 25 percent.

Then I got a piece of hickory from a tree that I cut down 8 days ago. I split it and checked it, it read 38 percent. This seemed bizarre to me. I know the meter only reads 50 percent, but this piece of wood should have been, in fact, 100 percent.
I put the piece of hickory in the bathtub and soaked it for 2 hours, patted it "dry" with a towel and read it again. It read 39 percent.

I think I have a faulty meter.

 

[Isaiah53]

It would never be 100% since that would be all water - 0% wood. The 38% and 39% readings was really just confirming that the wood was almost saturated with water and cannot absorb anymore. Not sure about the 15% reading. All of these pin type meters actually just measure the electrical resistance of the material between the pins, which is correlated to a moisture content.. Water conducts - wood and air do not. Not sure how accurate it actually is - most state as +/-3%. They are probably best used as a relative guide to help us determine what works rather than as an absolute value. I don't know that I would rush out and buy a replacement.

 

[Fastdonzi]

No, You'll never get 100%, Even if water was dripping out. Your findings seem Legit to me. I have checked fresh cut and don't recall ever getting over 40%... I think your meter is fine.

 

[johneh]

Before I wrote this I checked my 2 moisture meters
One is a inexpensive one for my fire wood
the other a very expensive one for my furniture shop
dipped both sets of points into a glass of water both read 50
as they should that's as high as they read . Went out to the
maple tree in the front yard striped a branch live tree
inexpensive meter read 39 % other read 40% so in conclusion
your meter works fine .
I have never seen a moisture meter read over 50%
If a peace of wood were at 100 % moisture it would
have to be made of water!

 

[Babaganoosh]

Take the meter and push it into the meaty part of your hand. It should register approximately 20%

 

[realstihl]

That could be painful!

 

[DougA]

That could be painful!

LOL

Your meter is probably about right. 2 yr dry locust my guess would be 18%. It depends more upon the type of locust. Black vs honey vs shademaster, etc. Big difference.
Fresh cut tree of any kind, yup, 40% range.

 

[Jon1270]

It would never be 100% since that would be all water - 0% wood. The 38% and 39% readings was really just confirming that the wood was almost saturated with water and cannot absorb anymore.

This makes sense intuitively, but it's all wrong. Wood moisture levels indicate the ratio of the weight of the water to the weight of the rest of the wood, i.e. what the wood would weigh if all of the moisture was baked out of it. So, a 100% moisture content would mean that the half the weight of the piece of wood is water. Levels that high are rather uncommon, but not unheard of. When living, Giant Sequoias have an average moisture content of 178%!

The other thing to know about electronic moisture meters -- the common, fairly inexpensive ones, anyhow - is that they're just glorified ohmmeters. They measure the electrical resistance of the wood, and use that as a basis for a guess at what the moisture content is likely to be. This works reasonably well as long as the wood is not too wet or too dry. When the real moisture content is above about 28%, the electrical resistance is so low that moisture meters simply can't get meaningfully accurate readings. If the real moisture content is below about 6%, then resistance is so high that electronic meters can't take a meaningful reading. Actual moisture contents below 6% are uncommon unless you live in Arizona or have been baking your firewood in an oven, but moisture contents above 28% are very common. When wood is that wet, you should take whatever your meter tells you with a big handful of salt. It doesn't matter that the scale goes to 40% or 50% on some meters; the electronics simply can't achieve useful accuracy when there's that much moisture present.

 

[dafattkidd]

I get that there is math and science behind it all, but based on my experience, your meter sounds accurate. Fresh cut wood usually comes in at 38%-beyond measurable on my cheap meter. Hard wood that has been split and stacked for two solid summers will come in at 15-18% range. My usual quick field test is putting the fresh split up to my cheek and feeling the moisture. That seems to be good enough for firewood standards.

In a few weeks test the fresh cut stuff again after being split and stacked for a few weeks. You should see some drop in moisture content. Or test it side by side with a buddy's meter.

 

[CTYank]

It would never be 100% since that would be all water - 0% wood. The 38% and 39% readings was really just confirming that the wood was almost saturated with water and cannot absorb anymore. Not sure about the 15% reading. All of these pin type meters actually just measure the electrical resistance of the material between the pins, which is correlated to a moisture content.. Water conducts - wood and air do not. Not sure how accurate it actually is - most state as +/-3%. They are probably best used as a relative guide to help us determine what works rather than as an absolute value. I don't know that I would rush out and buy a replacement.

Noooooo! MC readings of wood are DRY BASIS. IOW the reference material is zero-MC wood. So, it's water-weight/dry-wood-weight x 100 for a given volume of wood.

Reading of 0% is easy to understand. Reading of 100% means that for a given volume of wood, water weight = dry fiber weight. With some red oaks you can get MC > 100%.

 

[Simonkenton]

OK thanks for all the replies, I will stick with this meter.

 

[Jon1270]

With some red oaks you can get MC > 100%.

Also several species of fir, cedar, pine, hemlock, chinkapin, magnolia, blackgum, poplar, cottonwood, aspen, willow, basswood...

 

[Fastdonzi]

I have cut Black Walnut in the spring and the Log laying there had water flowing out of it like a hose for 10 min. I didn't have a meter then, sure wish I had.....

 

[Babaganoosh]

OK thanks for all the replies, I will stick with this meter.

Did you test it on your hand? What was the reading?

 

[Simonkenton]

OK babaganoosh I stuck it into my hand and it read 27.3
Did not draw blood.

 

[Fastdonzi]

No No....You Gotta Go Deeper..... For Calibration....

 

[Seanm]

I just tried my four point and it was between 30 and 32 in the palm of my hand. These things arent meant to be real accurate but just give you an idea.

 

[D8Chumley]

I thought I remember mine reading 32-35% in my palm. I'll have to go check that, or it will bug me
Ok it was 29-31% depending how hard I pushed