steamtreated

Steam-treated refers to materials that have undergone a treatment in which steam or water vapor is used as part of the processing, most commonly in wood. In wood, steam treatment is a form of thermal modification where the timber is heated in a steam-rich environment to elevated temperatures, typically around 160 to 260 degrees Celsius. The steam atmosphere helps drive chemical changes in the wood and serves as a heat carrier. The process is usually performed in a controlled chamber, involving a gradual temperature rise, a soak at the target temperature, and a controlled cooling and conditioning phase. The exact parameters vary by species and end use.

The primary goals of steam-treated wood are to improve dimensional stability, reduce swelling and shrinkage, and increase resistance to biological decay and insect attack, while also producing a darker, more uniform coloration. The color change is irreversible and often prized for its aesthetic. The treatment also lowers the wood’s equilibrium moisture content, which can reduce maintenance needs in some applications. Chemically, the process alters hemicelluloses and redistributes extractives, contributing to the observed changes in properties.

Applications and market terms vary. Steam-treated wood is marketed as thermally modified or steam-treated wood and is used for exterior and interior applications such as decking, siding, cladding, and furniture where reduced moisture uptake and enhanced stability are beneficial. The term may be used interchangeably with thermally modified wood, though specific formulations and equipment can differ.

Limitations can include higher cost and potential changes in strength or coating adhesion that are species- and finish-dependent. The performance of steam-treated wood is influenced by the species, treatment conditions, and subsequent processing.