Alabama Wood Crafters Share Wood Woes When Overlooking a Moisture Meter
The North Alabama Wood Crafters (NAWC) organization is a collection of committed woodworkers who produce everything from furniture to instruments. The group has monthly meetings and travels to local craft fairs to demonstrate various facets of woodworking, such as woodturning, carving, and marquetry.
One of NAWC’s goals, in addition to sharing the beauty of woodcraft with others, is to provide a forum and network for woodcrafters to develop their woodworking knowledge and skills.
One issue the NAWC team takes seriously is the need to measure moisture content (MC) of wood before working with it. In fact, a top raffle prize at its fundraiser last Christmas was an MMC220 handheld pinless wood moisture meter donated by Wagner Meters. The NAWC wanted to promote the use of moisture meters as not using one is a common mistake, especially by woodworkers using wood pieces light enough to weigh.
“When wood stops losing weight, the assumption is that it’s in equilibrium. But that doesn’t tell you the MC or if the wood is truly dry enough to work on. Moisture meters provide critical information other methods can’t,” says Tom Prohaska.
Bob Hovde is one NAWC member who could’ve benefited from that wood moisture meter on a recent woodturning project. He didn’t use a moisture meter to get a precise MC measurement but just weighed the wood instead. As a result, he experienced the frustration that happens when you don’t use a moisture meter to measure wood’s MC before working with it. Hovde shares what happened:
“This was a turned box like a round hatbox. Normally, you cut the lid and it fits perfectly. But if the lid and the box warp slightly differently as they dry because they have different MC, then you’ve got a lid that doesn’t quite fit the box anymore. That’s what happened to me. So both the lid and box needed to have about the same level of dryness.”
Wood is always wet – at least inside
Wood can release all its free water – that is the moisture in its veins and cells – and appear to be as dry as it’s going to get. However, don’t forget about all the bound water in the wood. Bound water is the moisture that’s chemically bonded with its cells. When wood loses or gains bound water, it changes the shape of the wood’s cells. That’s another way of saying it changes the wood’s shape. So it’s the bound water level that a woodworker really needs to know before starting a project.
Anyone who works with wood soon learns the importance of measuring its moisture content (MC). Build a cabinet from wood that’s too high in MC and excessive shrinkage, along with other problems, may occur as the wood dries. Build it from wood that’s too dry and the finish at joints may crack as humidity in the air increases.
Moisture meters use varying technologies to produce an MC reading. Pin meters measure electrical resistance. Pinless meters use electromagnetic signals. Both approaches provide a more precise MC reading than other moisture gauge methods.
The challenge pin meters present for woodcrafts is that it requires inserting pins into the wood, which damages the surface. Since MC testing needs to be done at multiple spots along wood to get a full picture of its MC and to detect any spots that are wetter or dryer than average, that means a lot of insertion points ruining the beauty and integrity of the wood. This makes pin meters particularly harmful for projects using thin, soft, or small pieces of wood.
Fortunately, pinless meters work with sensor pads that lay on top of the wood being tested. No penetration below the wood’s surface is required. Pinless meters also measure a broader area than do pinless meters, which speeds up the testing process. These qualities make a pinless moisture meter the perfect option for getting fast, accurate MC measurement on wood to be used in delicate or intricate projects.
Prohaska explains why the NAWC selected a pinless meter as its raffle prize, “When you turn a box or bowl, the walls are relatively thin. It would be destructive to use a pin-type moisture meter. The Wagner meter, however, which is pinless makes it possible to measure the moisture of a nearly finished article without damage to the surface.”
To learn more about Wagner’s line of wood moisture meters, click here.
Tony Morgan is a senior technician for Wagner Meters, where he serves on a team for product testing, development, and also customer service and training for moisture measurement products. Along with 19 years field experience for a number of electronics companies, Tony holds a B.A. in Management and his AAS in Electronics Technology.