Moisture meter

[fred henkin]

Looking for suggestions on moisture meters.
ie: pin vs pin less. Recommendations on actual meters too.

[Jim Andrew]

I have a mini-Ligno, bought it on sale from Grizzly. It has pins. You get a more accurate reading by cutting a board off, so you are not testing the end of a board. More accurate to test the endgrain in the center of a board. Cheap meters are not very accurate, the more you spend, the more accurate the meter. The wood DR, Gene Wengert says spend about 350$ to get an accurate meter.

[Kevin Jenness]

Delmhorst and Lignomat are the most widely used brands of resistance meters. With long enough pins and a way to drive them you can measure the moisture gradient from core to surface. I have had a Delmhorst J4 kit with a slide hammer for many years and it has served me well. It does require some calculation using species and temperature tables. More sophisticated models like the Delmhorst J2000 do those calculations automatically and allow for aggregated readings of multiple samples. If you often use thick wood it is a good idea to have extra long pins on hand.

Pinless meters allow non-destructive testing based on density. They give an average reading for a sample within their thickness range. Wagner is the most common type. I have one but I don't really trust it as I have gotten readings that diverge from my pin meter and oven dried samples. This may be due to the fact that species corrections are based on the average specific gravity of species whereas any particular sample may be inherently more or less dense than average. In any case, many people find them reliable. If you want instantaneous moisture readings without pinholes in your wood that is the way to go.

[Lee Schierer]

I also have the mini-ligno and it has worked well for many years. I don't use it often, but it works well when I need it. As Jim pointed out it uses pins and checking deep inside the wood can be difficult as you have to push the pins in by hand and deep penetration doesn't work well on woods such as hickory.

[Thomas Wilson]

I have an inexpensive ($24.10) General Tools pin-type moisture meter from HD. I bought it to diagnose and locate the source of dampness in a basement wall. It was good for that. I have used it three times for that kind of job. It worked and continues to work. So the cheap meters are useful. I won’t claim they are accurate but I was able to take a series of readings along the baseboard to locate the wettest spot. The variation was consistent and I found the leak. Fortunately, it was plumbing and not a foundation problem. The General Tools has a built in calibration resistor so you can test the meter to see if it is working as intended.

[Yonak Hawkins]

Regarding pinned vs. pinless : I don't know how your tolerance to the pin marks in the wood rests with you but, the pinless have their own drawbacks, such as having to know the density of the wood in order to get an accurate reading. I would say, unless you have a pretty good gauge of the density, which can vary pretty significantly, I have found, within a single species, the pinned would be more accurate.

[Doug Dawson]

Regarding pinned vs. pinless : I don't know how your tolerance to the pin marks in the wood rests with you but, the pinless have their own drawbacks, such as having to know the density of the wood in order to get an accurate reading. I would say, unless you have a pretty good gauge of the density, which can vary pretty significantly, I have found, within a single species, the pinned would be more accurate.

All the more reason to get a meter with species/density adjustment. I really like my Wagner 220 (discontinued recently and replaced by something a bit less expensive and seemingly more user-friendly.) My wood would look like it was infested by worms otherwise.

[Yonak Hawkins]

All the more reason to get a meter with species/density adjustment.

Yes, my Wagner MMC-205 can be adjusted for density but, for instance, I've found that the density of white ash can range from upper 30s to mid 50s which can result in quite a wide reading tolerance. That's my point about the accuracy of pinned vs. pinless.

[Doug Dawson]

Yes, my Wagner MMC-205 can be adjusted for density but, for instance, I've found that the density of white ash can range from upper 30s to mid 50s which can result in quite a wide reading tolerance. That's my point about the accuracy of pinned vs. pinless.

In monitoring the progress of wood towards dryness, I tend to assume that the boards will dry at roughly the same rate, properly stickered. This has never let me down. If we're talking about a single board in isolation, you've certainly got a point.

We know what the density of the wood _should_ be, and the calibrating meters rely on that. It's possible to make a mental adjustment if a board seems unusually heavy relative to its brethren.

[Yonak Hawkins]

Doug, I still think it's a craps shoot. I've had entire bundles of ash which the Forest Products Laboratory has identified as : "Fraxinus, slow growth, low density". As it turns out, it had a density of 39 lb./ft.³, whereas the Wagner chart uses a density of about 50.

Here is a disclaimer from the Wagner site : "Wagner has compiled species’ average specific gravity (SG) values ... from industry-accepted 3rd-party sources ...." This means there is a built-in tolerance and I have found this tolerance to be quite wide, especially with regard to ash.

[Doug Dawson]

Doug, I still think it's a craps shoot. I've had entire bundles of ash which the Forest Products Laboratory has identified as : "Fraxinus, slow growth, low density". As it turns out, it had a density of 39 lb./ft.³, whereas the Wagner chart uses a density of about 50.

Here is a disclaimer from the Wagner site : "Wagner has compiled species’ average specific gravity (SG) values ... from industry-accepted 3rd-party sources ...." This means there is a built-in tolerance and I have found this tolerance to be quite wide, especially with regard to ash.

You know the density of whichever species of wood you'd be selecting on the Wagner, because it's almost certainly taken from the published sources, probably "The Encyclopedia of Wood", a US Forest Service (as I recall) publication that everybody uses, or at least they used to.

The ultimate decider of what the density of a piece of wood is, is by weighing it, given that you know its dimensions. If the density varied significantly from the above reference, you might have a misidentification of the species, or you could just choose a species (from that reference) with similar density to what you're observing, and plug that into the meter.

IMO the borderline difference in whatever is actionable about how you handle the wood, between the Wagner-type meters and the hole-pokers, is not worth the cosmetic annoyance of having wormholes all over your workpieces. :^)

It's good to have this discussion.

[Kevin Jenness]

Doug,

The problem with assigning a density to a given piece of wood by comparing its volume to its weight is that the weight varies according to its moisture content, which is what you are trying to determine in the first place. As Yonak says, individual pieces or bundles of a particular species even if correctly identified can vary significantly from the published values, thus throwing off the pinless meter's assessment. For instance, I have dealt with widely varying shipments of Swietania Macrophylla (Honduras Mahogany) which would have suggested different MC's with a pinless meter due to inherent density differences.

Both types have their pluses, but I suspect that more kiln operators own resistance meters.

There definitely is an advantage to not poking holes in lumber. I don't do it often, mostly when purchasing wood from outside sources which I do less these days and for sampling a kiln load, but I rely more on weighing samples and acclimating lumber in the shop, which while not "climate controlled" is at least predictable throughout the year.

[Ed Aumiller]

Unless you are in the wood industry, you are probably just trying to get a reading to know how to use a piece of wood..
I have three moisture meters... A Delmhorst (pin type), Wagner (pinless) and a General (pin type)...
All three read in the same GENERAL ball park when measuring wood...
Yes, the Delmhorst is by far the most accurate in my opinion...
BUT I do not really care that much for most projects if the moisture content is 6.5% or 7.8% or 9% when making furniture...
BUT i do care if it is 13%, etc...

So unless you need very accurate measurement, probably any of the ones listed by others will work fine...

Now if you are a kiln operator, you need better info...

[Doug Dawson]

Doug,

The problem with assigning a density to a given piece of wood by comparing its volume to its weight is that the weight varies according to its moisture content, which is what you are trying to determine in the first place. As Yonak says, individual pieces or bundles of a particular species even if correctly identified can vary significantly from the published values, thus throwing off the pinless meter's assessment. For instance, I have dealt with widely varying shipments of Swietania Macrophylla (Honduras Mahogany) which would have suggested different MC's with a pinless meter due to inherent density differences.

Both types have their pluses, but I suspect that more kiln operators own resistance meters.

There definitely is an advantage to not poking holes in lumber. I don't do it often, mostly when purchasing wood from outside sources which I do less these days and for sampling a kiln load, but I rely more on weighing samples and acclimating lumber in the shop, which while not "climate controlled" is at least predictable throughout the year.

One of the often overlooked benefits of a decent moisture meter is in resawing. Say you have a plank that you're resawing for a bookmatch. The moisture level of the exterior and interior will not usually be the same. So when you resaw it, the two faces of the resulting board will have different moisture contents, and you should wait until they re-equilibriate before continuing with the machining. How do you know when that is? Bingo bango with a moisture meter you can know. It takes out the guesswork and optimizes the process. And you'd rather not have wormholes in the middle of your panels, thanks! :^)

[William Hodge]

Whatever you get, test it.
I bought a $100. moisture meter, and checked it by testing a saw horse left out in the rain, a board in the demo pile, and wood in the shop. all showed the same moisture content.
I sent the meter back, and bought a Lignomat pinned meter. I now have reality based readings. I check the same wood in the shop to see how the shop humidity is doing, in a general way.