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Wood drying (also seasoning lumber or wood seasoning) reduces the moisture content of wood before its use. When the drying is done in a kiln , the product is known as kiln-dried timber or lumber , whereas air drying is the more traditional method.
Further drying of the wood results in strengthening of the wood fibres, [1] and is usually accompanied by shrinkage. 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 North America, logs reach equilibrium moisture content at about 6% and 12%; [8] since most kiln-dried logs are dried down to about 18% to 20% moisture content, kiln-dried logs can be expected to shrink and settle over time, but to a lesser extent than green logs.
If the wood is placed in an environment at a particular temperature and relative humidity, its moisture content will generally begin to change in time, until it is finally in equilibrium with its surroundings, and the moisture content no longer changes in time. This moisture content is the EMC of the wood for that temperature and relative humidity.
Green wood contains more moisture than seasoned wood, which has been dried through passage of time or by forced drying in kilns. Green wood is considered to have 100% moisture content relative to air-dried or seasoned wood, which is considered to be 20%. Energy density charts for wood fuels tend to use air dried wood as their reference, thus ...
The true costs of the drying system can only be determined when comparing the total plant costs and risks with and without drying. [citation needed] Kiln dried firewood was pioneered during the 1980s, and was later adopted extensively in Europe due to the economic and practical benefits of selling wood with a lower moisture content (with ...
The wood moisture content is above 25% on a dry-weight basis; The environment is sufficiently warm; Oxygen (O 2) is present; Wood with less than 25% moisture (dry weight basis) can remain free of decay for centuries. Similarly, wood submerged in water may not be attacked by fungi if the amount of oxygen is inadequate. Fungi lumber/timber ...
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 ...