MOISTURE CONTENT OF THE WOOD20 April 2021
What Does Moisture In Wood Mean, What Level Is Acceptable?
MOISTURE CONTENT OF THE WOOD
Wood is a hygroscopic material, which means it absorbs water. Wood takes the water in three ways: as a fluid through capillary tension in the cell lumens, as vapour through the cell lumens, and as molecular diffusion through the cell walls. The moisture content of wood is the ratio of the mass of water in it to the mass of the timber without the water. (For example, if a 100 kg piece of wood contains 50 kg of water, the moisture percentage is 100 percent.) The moisture content of freshly sawn wood is typically between 40 and 200 percent. In normal use, the moisture content of wood ranges from 8% to 25% by weight, depending on the relative humidity of the air.
Moisture and water influence the properties of wood during both processing and use. The moisture content, for example, influences planing, gluing, and surface treatment, as well as key properties such as sizes, endurance, and resistance to degradation, durability. As a result, it is critical to understand how moisture affects wood and how to test its moisture content.
The moisture content of wood is calculated by dividing the moisture content by the amount of dry material in kg. The moisture content, u, is defined as the ratio of the weight of the wet material to the weight of dried wood after drying at 103°C.
How Does Moisture Affect Wood?
We'll see how wood reacts to moisture in the environment. Wood moisture content should always be on your mind if you are a cabinet maker, a wood flooring professional installing hardwood floors, or if you use wood in construction. Wood is a hygroscopic material. As the relative humidity (RH) of the surrounding air changes, it gains or loses water moisture.
Because of the variable humidity levels in the surrounding air, wood not only gains or loses water moisture, but also expands and contracts. As the humidity rises, so does the wood moisture content, going to cause the wood to expand.
The wood moisture content decreases as the humidity decreases, going to cause the wood to shrink. When the wood does not gain or lose moisture, it means it has reached its equilibrium moisture content (EMC). Wood moisture should be calculated with the wood moisture meter.
Wood should always be allowed to acclimate or balance with the RH of the end-use location. Inability to do so will result in warping, cracking, and other issues after the wood products are built.