The Kiln Drying Process

Transparency and Care

Kiln drying serves to efficiently bring green lumber moisture levels down to a workable range – moisture content levels that will not end in the myriad of problems that can be caused by excess moisture levels in wood. These problems include warping and twisting in dimensional lumber, binding or kicking during machining, buckling or crowning in table tops. Kiln-dried wood is wood that has been dried in an oven (kiln). With a kiln, you can control the environment such as temperature, humidity, and steam levels for a set period of time. Allowing you to dry wood to the desired moisture content faster than air-drying.

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Air-drying lumber simply means to stack lumber and expose it to the outdoors. Drying can be done either by air or kilns, which use circulating heated air to more rapidly remove the excess amount of moisture from the wood. After the kiln dried lumber has reached the correct moisture level for that species, it is sent through to processing for finished dimensions. 

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Kiln drying significantly reduces the moisture content of wood but there’s more to be considered. The reality of wood’s nature, and indeed, part of its attraction over the centuries, is that it is a hygroscopic material. Until it is fully sealed, wood constantly interacts with moisture in its environment and will absorb or release moisture as necessary to find a balance with its environment.

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Wood may have much of its moisture removed during the kiln drying process, but it does not lose the ability to reabsorb moisture that is in its environment. It might be a direct water source, moisture in adjacent material or even humidity in the air; wood’s cellular structure will be ready to absorb any moisture it contacts.

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Any completed wood project or product can be jeopardized by moisture imbalances in the wood used.