How to Choose a Live-Edge Slab

Wood is dimensionally stable above the fiber saturation point, which averages about 30 percent moisture content. Below that point it shrinks as it loses moisture and swells as it gains moisture, and that shrinking and swelling is what can lead to warping, checking, and splitting.

Wood does not move evenly. It moves most across the growth rings, tangentially, about half as much across the rings radially, and only slightly along the grain. Tangential movement is roughly twice radial movement, which is why a wide slab reacts more across its width than along its length.

Equilibrium moisture content is the moisture content at which wood is neither gaining nor losing moisture, and it depends on the room. At about 70 degrees F and 30 to 50 percent relative humidity, indoor wood tends toward roughly 6 to 9 percent moisture content, per the Wood Handbook Table 4-2. That range describes general indoor behavior at those conditions. It is not a moisture level for any particular slab, and a finish slows moisture change without stopping it, so the slab's moisture condition still matters after finishing.

Surface checks are small splits along the grain that form when drying stresses exceed the wood's strength across the grain, as the surface dries much faster than the interior. End checks form because a slab dries much faster from its ends than from its faces, which is why ends are often coated during drying. Honeycomb is internal checking that can be invisible on the surface and only appear later when a slab is machined.

Because wood keeps exchanging moisture with its surroundings, the general aim is to bring a slab close to the moisture content it will reach where it will live, and to let it settle toward that environment before final work. Look a slab over for visible checks and cracks, and remember that internal checking may not show on the surface, so inspecting the individual piece is part of choosing it.