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Equilibrium moisture content in wood. In heartwood it occurs only in the first and last forms. Wood that is thoroughly air-dried (in equilibrium with the moisture content of the air) retains 8–16% of the water in the cell walls, and none, or practically none, in the other forms. Even oven-dried wood retains a small percentage of moisture, but ...
Equilibrium moisture content of wood versus humidity and temperature, according to the Hailwood-Horrobin equation. The equilibrium moisture content (EMC) of a hygroscopic material surrounded at least partially by air is the moisture content at which the material is neither gaining nor losing moisture.
Water content or moisture content is the quantity of water contained in a material, such as soil (called soil moisture), rock, ceramics, crops, or wood. Water content is used in a wide range of scientific and technical areas, and is expressed as a ratio, which can range from 0 (completely dry) to the value of the materials' porosity at saturation.
The chemical potential of sorbed water is a function of wood moisture content. Therefore, a gradient of wood moisture content (between surface and centre), or more specifically of water activity, is accompanied by a gradient of chemical potential under isothermal conditions. Moisture will redistribute itself throughout the wood until its ...
A Assuming an altitude of 194 metres above mean sea level (the worldwide median altitude of human habitation), an indoor temperature of 23 °C, a dewpoint of 9 °C (40.85% relative humidity), and 760 mmHg sea level–corrected barometric pressure (molar water vapor content = 1.16%). B Calculated values *Derived data by calculation.
Wood is normally dried to a point where it is in equilibrium with the atmospheric moisture content or relative humidity, and since this varies so does the equilibrium moisture content. Laboratory testing has found the average FSP in many types of wood to be approximately 26%. Individual species may differ from the average. [2]
Moisture content is measured in the same manner as wood and displayed in Wood Moisture Equivalent, or WME. WME is the theoretical moisture content that the substrate would contain if it were wood. This ability to locate and measure moisture anomalies can help manage and control indoor air quality by locating and preventing hidden mold growth ...
When free hydroxyl groups are transformed to acetoxy groups, the ability of the wood to absorb water is greatly reduced, rendering the wood more dimensionally stable and, because it is no longer digestible, extremely durable. In general, softwoods naturally have an acetyl content from 0.5 to 1.5% and more durable hardwoods from 2 to 4.5%.