The moisture content of your wood is one of those horrible little things that you must constantly be aware of. No one wants to build a cabinet and then find out a year later that a panel has shrunk by a 1/4" or more. Some of the more common moisture problems that can occur are shrinking, warping, swelling, delamination, bad finishes, and loose joints. Most of these problems can be solved by making sure you have dry, stable wood that has acclimated gradually to your shop's climate. And here's where we get into what is called Equilibrium Moisture Content.
Simply put, EMC is a state of moisture saturation that has reached a stable point (relatively speaking). Before you mill up that beautiful piece of maple you need to figure out if its moisture content is the same as your shop's. If the moisture content of your wood is not very close to the moisture content of your shop, bad things can happen. So how close do the two need to be? One article we found from the January 2010 Fine Woodworking Magazine stated that "...even a 2% change can mean a lot. In general, a 1% moisture change in hardwood will result in a bit less than 1⁄32 in. of expansion or contraction per 10 in. of board width. A 2% moisture difference results in a dimensional change of 1⁄16 in."
To calculate your shop's EMC you need only know the temperature and relative humidity. Then you can use a handy online calculator like this one here to figure out your shop's EMC. And if we know the relative humidity and temperature, and therefore the EMC, of any location where your lumber is stored, we can quickly find out the optimum moisture content of the lumber you'll use for your projects.
So now you know where this is heading right? To make beautiful woodworking projects that stay structurally stable you'll need to know the moisture content (MC) of your wood. And you can't do that by touching it or even by staring at it, you'll need a high quality moisture meter. In the Infinity Tools Wood Lab, we really love the Mini-Ligno Lignomat Moisture Meter with Electronic Display.
The Mini-Ligno E/D is an affordable pin style meter that will tell you exactly what the moisture content of your wood is.I have had a nice chunk of Rosewood that I've been aching to resaw into a bunch of parts for some boxes, but I've really wanted to make sure it was acclimated to my shop before I used it. That's where the Mini-Ligno comes into play. Rated the Best Overall Choice by Fine Woodworking Magazine (January 2010), this super easy-to-use pin-style moisture meter can tell me exactly when I am good to go. The device comes with a nice soft storage case that helps to keep it dust free when not in use. There is also a green protective cap that makes sure your pins don't get damaged and when placed on the end of the device, gives you a nice curved support that mimics the contour of your hand. Between the two pins is the on-off switch. Whenever you push the pins into a chunk of wood, the on-off switch is automatically engaged making operation a breeze.
The Mini-Ligno Moisture Meter is a perfect sized tool that gives you accurate readings easily
The ergonomically designed green protective cap when placed on the other end of the meter gives your hand a comfortable grip for easy pin insertion.
The Mini-Ligno comes with two sets of pins (3/16" and 7/16" long) to help you get accurate readings every time.
In between the two pins is the on/off switch. You can press the switch twice to toggle back and forth between the two wood groups.
The Mini-Ligno is an accurate, easy-to-use device that will really help you pinpoint moisture issues in your wood and keep wood movement issues in check. It's also portable and will be a good tool to have with you when shopping for wood at the lumber yard. Moisture meters are also outstanding for when you need to replace a part on an antique piece of furniture. You can make sure that the piece of furniture and the replacement part have the same moisture content.
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