Defectfree Drying

Drying wood in a kiln is not as simple as popping frozen fish sticks in the oven. Drying wood too fast causes problems. To avoid warping, splitting and other degrade problems, temperature and humidity must be kept at levels that dry the wood slowly.

Wood shrinks when it dries out. This shrinkage creates internal stresses in the wood that can cause splits, checks, warp or honeycomb. Careful stickcring will help keep warping under control. To control the other kinds of defects, you have to control the rate of moisture loss.

End checking results because the ends of a board or log lose moisture faster than the middle. These splits can run right on up a board, destroying it. You can reduce end checking by slowing the loss of moisture from the end grain.

As soon as logs have been trimmed and cut to length, coat all end-grain surfaces with a wax-emulsion end sealer such as Anchorseal. (See Sources.) You can brush it on in the woods and it will help protect against end checking right on through sawing and drv ing. (Oil-based paint is better than no sealer at all.) If you buy logs that haven't been end sealed you should seal them immediately. Prompt and proper end sealing is by far the most cost-effective (and most neglected) step you can lake to ensure thai vou'll end up with high-quality lumber.

Surface checks are cracks that develop when the surface of the board shrinks faster than the interior. Protect sawn boards from surface checking by keeping them out of direct sunlight and by following recommended kiln schedules if you dry your lumber with heat or dehumidification.

Honeycomb is checking inside a board. Honeycomb is a drying-related defect caused by the stresses that result from drv ing a board too fast.

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