Selecting a Good Moisture Meter

More money buys a better instrument, but your choice depends on your needs. December 14, 2009

I have several thousand board feet of 'urban forest lumber' in 4/4, 8/4 and 12/4 thickness. I would like to follow the moisture content so I would know when I might use it. However, I find moisture meters from $50 to $750. I have no idea as to the desirable [or undesirable] features. What should I do? I am in the northern San Joaquin Valley of California. I have claro walnut, cork oak, madrone, manzanita, redwood, aspen, black locust, and several other varieties.

Forum Responses
(Sawing and Drying Forum)
From contributor J:
Dr. Wengert will probably be along to answer you in detail (or you could search the Knowledge Base), but I believe his typical advice is that you have to spend at least $150-$200 to get one that works well. I bought a $60 cheapie that is, well, not so useful.

From contributor S:
I have a Lignomat mini which I believe sells for about $100. Seems to work fine
for me but to get a really good one I think you have to spend more money.

From contributor A:
I have a Delmhorst that cost about $350 and it is a good one. I also have a Lignomat that cost about $150 and it is good for just checking. The Lignomat may say 10% and the Delmhorst will read from 8 to 12 % in the same load. It is just a finer reading meter. I would expect to pay between $200 and $500 for a good meter depending on what features you need. I like the short pin type best. You should find a "J" Lite pin type or a "J-4" a good meter for what you want to do. Good coin spent on good tools will repay you many times over because if you say the wood is dry and it is not, they will not be customers any more. Repeat business is the key.

From contributor B:
Contributor A is right - spend the coin on a good meter. The last thing I wanted was to sell KD lumber, receive a complaint on it, and find that my customer was using a clearly more accurate meter than me. I went with the Delmhorst RDM3, and did spend handily for it, but I don't regret it. For the various thicknesses you have, it would be handy to have a meter that can tell you both surface and core MC. With mine I went with the hammer probe so that I can check not only MC at the surface (3/8"), but can set my meter to continuous read and run the hammer insulated probes into the lumber until I hit the wettest spot (normally the core). That gives you a better idea of the range of MC you’re dealing with from core to shell. One other thing, with the several spp you have, you should check into the ability of any potential moisture meter to species correct for the species you're using, and along the same lines, temperature correction. I forgot to adjust the temperature on mine when drying 4/4 oak recently (I had the meter set 20 degrees from what it actually was) - had to go back and redo all the reading, and there was about a 2% MC difference.

From the original questioner:
I may have not clearly stated my use for the moisture meter. I have stockpiled 'Urban Forest Lumber' for the purpose of only my own use. I need something to guide me as to the suitability for use. I will not be selling any lumber. The units suggested would have me spending $600-$900 to become compliant in the 'KD Lumber Market Place'. I have no intention of ever going there. Is there something a bit less that would fulfill my needs?

From contributor D:
I am posting a website where you can buy a meter. The "J-lite" is listed for $145 and that should get you where you want to go. There are others you can look at.

From Gene Wengert, forum technical advisor:
I suggest that you get a digital meter that cost no less than $200. I also suggest that you get a "name brand" meter as it will be more reliable with American species, easier to repair. Further, it is more likely that the customer will have a similar meter. Some of the lesser known meters or less expensive meters are not too accurate, so your customer may come up with some strange (and wrong) values. Insist that "any moisture claims will be based on readings taken with a Delmhorts RDM-3 with insulated needles and appropriate species and temperature corrections with the needles driven 1/4 of the thickness of the pieces." (Or if you use a different model or brand, change the previous sentence as needed).

From Gene Wengert, forum technical advisor:
I have done a study comparing a Delmhorst, Wagner and Lignomat on KD lumber. The results are widely published. For example, see page 130 (actual page and not PDF page) in “Drying Hardwood Lumber”. All three meters were close, but it seems to me that Delmhorst was the closest. Although the Wagner goes much lower in MC than the others, which is good indeed, and is not greatly affected by wood temperature, it is greatly affected by density variations in the wood. Read the article for complete info.

Here is the average difference between the oven-dry MC and the meter reading for the three meters: Delmhorst pin; Lignomat pin; and Wagner pinless.

Ash 0.8 0.9 -1.2
Aspen 0.6 0.3 2.5
Basswood 0.4 0.1 -1.9
Yellow birch 0.8 1.0 —
Cherry 0.4 — -1.2
Hard maple 0.5 0.7 0.1
Soft maple 0.5 -0.9 1.4
Red oak 0.6 0.5 1.2
Walnut 0.3 0.9 -0.1