Q: We are in a discussion about the role that water and moisture plays in bending wood. I know that how well a piece bends is dependent on the moisture content of the wood but what role does the moisture play in the plasticity of the sample? If you were to take a piece of wood that is oven dry and we're able to cool it in a chamber with 0 percent RH, would application of heat alone be enough to bend the piece and maintain it's shape?
A: Heat does indeed make the wood plastic, which is what we need in order to bend wood and have it maintain its bent shape. (If wood were only elastic, it would bend, but then when the bending force was released, the wood would return to its original shape.)
Moisture extends the plastic range of wood. I cannot say which factor, heat or moisture, is more critical; both are important, but perhaps heat is a bit more important than moisture. Note that at 0 percent MC, the wood is so brittle that the plastic range is very small. Failure can occur as soon as the wood bends a little bit even when using heat to plasticize the wood.
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