What is equilibrium moisture content and why is it important?
In many different industries involving the use of wood or other moisture absorbing materials, you may hear the term 'EMC' mentioned from time to time. Although industry veterans are very familiar with this term, it may not be familiar to beginners in the woodworking, flooring, or repair industries.
So, what is EMC and why is it important for people who frequently use wood?
For people who frequently use wooden products, there are several reasons why knowing the importance of wood achieving its EMC will be influenced by the average moisture content of the area where the wood is located. Used it.
Firstly, when wood absorbs or releases moisture, it expands or contracts. The more water is absorbed or released, the more severe the expansion/contraction of wood products.
For example, suppose you are installing a set of wooden flooring boards on a construction site with an average moisture content of 11%, which indicates a humid environment. However, the wooden board initially adapted to an area with an average moisture content of 6%, indicating a drier environment.
When exposed to a "humid" environment, the wooden board will begin to absorb moisture from the air and slightly expand. This may cause the installed wooden boards to start cupping or warping, as their expanding mass pushes other wooden boards - causing damage to the floor and damaging its appearance.
Check the EMC in the wood and the average moisture content of the structure/area
So, how do you check the EMC of wood? A good method is to check the% MC of the wood multiple times within a few days in the installation environment. Use a wood moisture meter to measure the moisture content of the wood every few hours until the% MC reading stops changing.
Based on the original moisture content of the wood, the temperature of the new environment, and the relative humidity of the area, it may take several days for the wood to fully adapt to a specific environment. Generally speaking, the more significant the difference between the moisture content of wood and its EMC point, the longer it takes to fully adapt to the environment.
Now, you may want to know how to determine the average moisture content of a region. If you look at the map of the United States here, you can see that the average moisture content in most parts of the country is 8%, while some coastal areas have an average moisture content of 11%, and drier desert areas are close to 6%.
Although this can give you a rough idea of what will happen, it may be necessary to obtain more detailed information by conducting RH measurements in the area where you installed the wood.
To obtain a relative humidity (RH) reading, you need a temperature and humidity meter that can measure the temperature and humidity conditions in a large area of the workplace. The RH reading obtained from the hygrometer can help you understand what the EMC of on-site wood products should be.
For example, if your RH reading is between 58% and 63% RH, then your average moisture content is about 11%.
Detailed humidity information, such as RH and EMC, can help you make wiser decisions in woodworking, floor installation, and repair, thereby avoiding costly errors.
