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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. There are two main reasons for drying wood:
The Thermo wood process consists of drying, heat treatment and finally cooling/conditioning, and takes up to 72 hours.[4] The Plato process consists of hydrothermolysis, dry curing and conditioning, and can take up to 7 days. The required time depends on wood species, width and initial moisture content. [5]
However, in the 1980s, the development of chemical treatment processes allowed the wood to be more widely used for furniture making and frames. Rubberwood is generally treated soon after sawing by pressurized immersion in boron preservative solution to diffuse the chemicals. Then, the treated timber is kiln-dried to reduce its moisture content ...
Green wood coming straight from the felled tree has far too high a moisture content to be commercially useful and will rot, warp and split. Both hardwoods and softwood must be left to dry out until the moisture content is between 18% and 8%. This can be a long process unless accelerated by use of a kiln.
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.
Wood treated with this process is often used for cladding or siding, flooring, furniture and windows. For the control of pests that may be harbored in wood packaging material (i.e. crates and pallets), the ISPM 15 requires heat treatment of wood to 56 °C for 30 minutes to receive the HT stamp.
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 ...
The product moisture content is then constant at the "equilibrium moisture content", where it is, in practice, in equilibrium with the dehydrating medium. In the falling-rate period, water migration from the product interior to the surface is mostly by molecular diffusion, i.e. the water flux is proportional to the moisture content gradient.
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