I received this question in episode 3 of the Ask Brian Boggs Show:
I’m just starting out. How important is it to use a moisture meter?
Well, if you’re making spoons, it’s not all that important, but if you’re making furniture where you’re gluing things together, or using joinery, where parts are bonded, or fixed together, moisture content is as important as position, and selection of material. In order to get any joinery to work well you have to have a position of the two mating surfaces that are being bonded with glue have to be precisely cut. The adhesive has to be properly applied, clamping pressure has to be appropriate. If the moisture content is too high that alone can cause failure when everything else is done beautifully. There is nothing more important than understanding the moisture content of which you’re working with.
I worked… probably six years, or so, as a greenwood chairmaker, or ladder back chair maker, before owning a moisture meter. Are those chairs still holding up? – No. The joints are not as tight as I would like. I think, it’s more important that you somehow have a way of detecting moisture content. There’s a number of ways you can do that. John Alexander in his book, “Make a Chair from a Tree“, talked about tapping the woods together to listen to them. That’s only good if you’ve been working with wood long enough to know what dry hickory, and 3/4” rounds, are supposed to sound like. The growth rate, and the dimension of the particles, is going to impact sound too. That was a tricky one, but that is what I started out using.
Now that we’re using a moisture meter, I use it all day. I have my employees sharing it. It’s in use many times every single day because wood changes moisture content throughout a day. We’ve got several different projects going on a once. We need to know at glue up time, or at the time that we’re cutting the joinery that we’ve got the parts at the appropriate moisture content, which is generally 7% to 8%. When you’re using a moisture meter though, you still have to pay attention to all of the other signals that a traditional wood worker, not using a moisture meter, would have to pay attention too.
Does the wood feel moist? If it’s been drying, and it’s getting dryer, and dryer, and dryer, and you’re reading the surface with a moisture meter, you’re going to get a lower reading than is what in the core. If the woods been drying for 10 years you’re probably going to get a relatively accurate metering from the surface, but you’ve got to cut the wood open, and read the core whether it’s a pinless, or a pin type. This is especially tricky with walnut. We’ve had a lot of issues trying to get walnut dry enough. Until we open the wood up we don’t know, meter or no, we don’t know if it’s properly drying, or dried far enough. Yes, moisture meter is very important, but it’s just anything else, it’s user attention that assures you know you’re moisture content. Not just an electronic tool.
Here’s The Moister Meter I Use
I use a Wagner. It’s probably about 10 years old. It’s one of those little pinless Wagners. I don’t use a pin type because too many times when I’m checking the moisture content I’m checking a piece of wood that I can’t put pin prick holes in. I need that surface. If I need to read deeper into the surface I’ll keep a part of that wood attached to the board that I’m needing to dry that it can sacrificed, and cut open. Or, as I’m machining the wood, I’ll check periodically, as I expose a new face, that that new face is reading consistent with the surface reading. It’s one of the cheaper moisture meters, but I’ve compared it to others that friends are using. It seems to be every bit as sensitive, and accurate, as the more expensive ones.