Glossary:
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Even though a piece of wood may be long "dead", it is by no means immobile. Water, whether in the form of humidity in the air or fluids that come in contact with the wood, will penetrate the wood and cause the cellular structure to expand. This can cause several problems that must be accounted for in constructing fine furniture. First, most wood will warp or cup. This is caused by the two flat surfaces of the wood expanding at different rates. If the bottom face of a board expands more than the top surface, then the board will "cup" upwards. If one edge of a board expands more than the opposite edge, the board will warp off to the slow side. Even if the board does expand evenly through out it's dimensions, it still expands. If this expansion is not considered while planning a piece, the power of this expansion will break joints apart and buckle panels. As the wood dries out again it will contract. This contraction can open up cracks between parts or cause parts to rattle and cause panels to split if they are not designed properly. This expansion and contraction continues, over and over as the atmospheric humidity changes throughout the life of the furniture piece. If it's properly designed, allowances have been made for this movement. If not, movement within the joints will crack the glue, shrivel mating parts so that they no longer fit tightly, and the joint will come apart. Even using expensive kiln dried lumber will not prevent wood movement. For no matter how you dry it the wood will still absorb moisture from the air even through a finish. Gluing up large panels like a table top requires extra care to be sure the thing isn't going to curl up on one corner or hump in the middle. It takes someone experienced in "reading" the grain of the wood and knowing how the wood will react to lay out a stable panel. You have that at Smoky Mountain Woodworks. |