Thermowood - A Material Investigation

Mark Smith, CEO of Fibre-Gen, gave us a wide brief of 'I'd like you guys to come up with some stuff'. The team developed a wide range of possibilities that might test the boundary between indoor and outdoor furniture.

Thermowood had great attributes; it could function outdoors above ground, and did not need staining or colouring in any way. The technology offered a more sustainable alternative to existing preservative treated timbers that used a lot of solvents and inorganic active ingredients. The timber is put into a kiln at high temperature in a reduction atmosphere (without oxygen) which both colours the timber and lowers its effective moisture level, thus making it more able to meet the demands of an exterior application.

The design team created several cross over pieces: a bench seat (Fernlief); a space divider and storage unit (Stoe); shelving (Sterling); and tall stools (Blane). The objects tested the permeable boundary between the house and the outdoor room by developing designs that could operate both indoors and, as a consequence of materials, function well outdoors also. The material played a central role in the design. The

This product tested the boundary between interior and exterior furniture

colour selected was a mid range temperature equated with cherry, and this was complemented by fabricated stainless detailing and 316 fasteners to ensure complete exterior durability.

The results were taken as part of the Urbis Lounge at the 2004 DesignEx Exhibition in Melbourne and was awarded a commendation by the judges. Locus Research also utilised the material as a flooring substrate that was assembled onsite into the Design Room; this was awarded a New Product Award.

The project was closed with a complete production and manufacturing appraisal of the materials which enabled CHH to understand some of the key advantages and issues with the new material.

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The Thermowood Installation

Thermally modified timber originating from sustainably managed New Zealand forest plantations could be the answer to the increasing demand for an alternative to tropical hardwoods in environmentally responsible design. Most properties of thermally modified timber resemble those of tropical hardwoods. “This is the first genuine alternative to tropical hardwood, so it is a significant step towards sustainable design,” says Timothy Allan, Managing Director of New Zealand product development company Locus Research.

For the first time, the design community can see the capability of thermally modified radiata on display in the Urbis lounge. An outdoor bench seat and a free-standing room divider-cum-shelving unit beautifully display the versatility and properties of this wood product.

Designed by Jared Mankelow from the Locus Research team to explore the potential of the new material, the bench seat uses three different coloured layers of the timber in a cross-directional laminate. The grain enhances the surface of the seat pan, whilst the timber’s natural resistance to moisture and decay-causing fungi makes it an excellent option for outdoor furniture pieces.

The room divider/shelving unit features a machined backing screen which filters light and glimpses of the displayed objects from the other side. The dark brown timber gives a real presence to the piece, and machined patterns in the screen promote the exploration of textures in the piece.

Thermally modified timber is produced by heating the wood at very high temperatures in an inert (oxygen-free) kiln environment, causing changes in the cellular structure of the wood. The greatly reduced moisture content and increased stability of the timber makes it suitable for a wide range of indoor and outdoor applications including cladding, joinery, decks, and furniture.

The drying process also causes changes in the colour of the wood, while maintaining the natural grain of the wood. It can be produced in a variety of shades from golden ochre to dark brown. The colour change is uniform throughout the wood, eliminating the need for stains or applied coatings.

Timothy’s verdict is that no other outdoor timber product compares.