For the purposes of this article I am going to focus on the steam-bending aspect involving the legs as that is the technique that woodworkers seem the most reluctant to try. There are actually a great number of possible ways for making the seat itself, including carving it from solid, as well as laminating and kerf-cutting as illustrated here. For the legs and under-stretchers though there is nothing as efficient, attractive and economical as steam-bending them from solid wood.

To understand the steam-bending process, it helps to think of wood as composed of bundles of long hollow rods, surrounded by lignins which act as a kind of thermo-plastic glue. The action of boiling steam happens to be just the right medium for temporarily softening the lignins, allowing the hollow rods to be shifted and slid past each other, achieving bends way beyond the unheated wood’s natural flexibility . It will then pretty much stay put in its new configuration if it’s held securely in place while the lignins cool down and re-set.

The moisture has some softening effect but it is principally the heat that is involved, and steam at 100 degrees, not pressurised, has been found to be the best way to heat-soften timber. There are chemical processes that can do the same job actually but they are far more expensive and technically challenging.”

Read more in the Aug/Sept 2010 issue of The Shed