Steam-bent furniture
What is steam bent wood?
Steam bending is an ancient and fascinating technique in woodworking that makes it possible to bend solid wood in all three dimensions.
The process works using three main elements:
Heat and moisture: The most common types of wood for steam bending are beech, oak, ash and maple. The wood is not kiln-dried, but relatively fresh. The workpiece is placed in a closed box, where it is exposed to steam under atmospheric pressure. The steam softens the internal structure of the wood, especially lignin (the substance that "glues" the wood fibres together).
Bending: When the item is heated (this takes about an hour per inch of thickness), it is removed from the box. A steel band is attached to the outside. In this way, the fibers get torn apart. During bending, the fibers on the inside of the bend curl up, while the fibers on the outside are unaffected.
Drying: The workpiece is fixed during drying. When the moisture disappears, the lignin hardens again and the wood "locks" into the new, curved shape.
Why use steam bending?
An alternative to steam bending is lamination, where veneers or slats are glued together in a moulding tool. Commonly, lamination is two-dimensional, whereas steam bending can be three-dimensional and thus has some other aesthetic possibilities. The technique enables the flowing, unbroken lines that are known from the classic Thonet chairs, which revolutionized the furniture industry in the 1800s with this method.