11 September 2010

wood: a natural composite material

Wood is made up of lignin and cellulose. To make the wood adequately pliable for steam bending, the lignin, which bonds the cellulose chains together, must be softened (plasticised) to reduce its strength. This is achieved by steam treating the wood in a pressure chamber.

When the ligning becomes plastic the wood will compress very readily, but will break when stretched by more than about 1%. Therefore, bends are formed by compression.

Part of a bentwood coat stand by Thonet. Image from MPFDP