Pinless moisture meter

[Mark Rainey]

Got a Wagner Orion pinless moisture meter from Lee Valley recently. I like it. I have a table top in my basement unfinished for the past 9 months. I keep my relative humidity between 40 and 55%. The cherry lumber was kiln dried from a quality sawmill and after a month or so I glued up the top which consisted of 2 boards from different trees. When I measure the relative humidity of one board it is 9.7, ( I like my boards between 7 and 10% in Pennsylvania ), but the other board is at 11.6%. I called Wagner and they said same species boards ( such as cherry ) can have different densities ( there is a density setting for cherry on the meter ) and they could actually have similar moisture content. Any others have experience with this?

Wagner 1.jpgWagner 11.6.jpg

[Jimmy Harris]

All I can say is that I've found it's best to not use moisture meters to look for an exact reading, but rather to monitor changes. So I'd just write down those numbers and check them again in a week or so. If they both stay the same or follow each other rather closely, then you'll know both boards are similar in moisture content. If the board with the higher moisture drops more, then you'll know it wasn't as dry as the other. It's not too uncommon for two boards from the same mill to have different moisture levels. One could be newer, one could have been sitting on top and more exposed, or one could, as the salesman said, just be denser than the other or have different minerals in the wood.

A moisture meter doesn't really read moisture. It reads electrical resistance and estimates a moisture level based on that. Pinless moisture meters use electromagnetic waves to penetrate the wood and are thus more sensitive to a wood's density than the pin type, and so can give less accurate readings as wood densities change. So it's not uncommon to see different readings on the same wood with the same moisture level. But just because it's not uncommon, doesn't mean it's not also an indication of there actually being different moisture levels. That's why you need to take multiple readings across a longer time span and record your readings to look for changes. Because that will tell you what you really need to know. Not the actual moisture content, but whether or not the wood is dried and acclimated to your environment.

[Bernie Kopfer]

Thank you Jimmy, for the concise tutorial on the use of moisture meters.