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Osmose's Micronised treated timber decking

Fresh look at treatments
Published:  03 November, 2010

Timber treatment companies are injecting new interest into the outdoor timber market by developing technology that gives wood a “clear more natural finish”. Stephen Powney reports

We’re used to seeing treated timber with a green or brown tinge. In fact, the presence of a colour is often seen as automatic confirmation that it has been treated.

But treatment companies have developed new technologies to provide a wider range of treated timber aesthetic options. Among these is Osmose’s micronised system. This is designed as a “next generation copper treatment system”, with copper in suspension in the treatment solution rather than dissolved, as with traditional Alkaline Copper Quartenary (ACQ) products.

“By grinding the copper in a suspension, when it goes into the wood it makes it look very different. Instead of a dark green product it’s clear-looking,” said Osmose European marketing director Andy Hodge. “In vertical applications the colour lasts a couple of years before turning grey and in horizontal applications, depending on species and the level of heartwood/sapwood content, it lasts about 18-20 months. That compares with 12-14 months with ACQ treatments”.

Osmose sees opportunities for a new product with a “different weathering profile” and says it could inject a bit of life into the decking industry in particular. In fact, a leading timber company is bringing out a new decking range based on the treatment which is to be sold across the UK, while a range of Richard Burbidge products treated with MicroShades are being stocked by a major DIY retailer from 2011. M&M Timber and Brookridge Timber are also using the treatment.

Colour pigments – MicroShades  – featuring ground iron oxide can be added to the treatment to give more colour options. “It makes the softwood look more like a hardwood,” added Hodge. “There is a lot of variety and a very subtle colour. And our data shows the decks with pigments still have their colour after two summers.”

Adding to the attraction of micronised products, he said, was that they don’t use the aggressive solvents used in ACQ treatments to dissolve the copper.

Osmose has also developed a stabilising oil finishing system, which can be used in addition to traditional treatment or micronising. This features a hot oil process which penetrates the wood and causes water to bead. It was trialled with the American Hardwood Export Council in architect David Adjaye’s 2008 London Design Festival tulipwood pavilion. The oil was specified to allow the timber, generally an interior joinery species, to perform outdoors.

In combination with pigments, it also gives wood longer colour life. “It’s not commercially available yet,” said Hodge, “but we will see companies going into it.”

Arch Timber Protection, meanwhile, has launched Tanalised Clear, a pressure treatment for exterior, above ground and decorative applications, such as cladding, deck boards and garden building components.

Tanalised Clear-treated timber is protected with Tanalith M, a metal-free wood preservative designed to maintain wood’s natural colour and appearance.

Introduced as part of Arch’s Year of Innovation 2010, Tanalised Clear is designed to develop a “distinctive sun-brightened appearance”.

The company said the product uses “proven high-pressure technology” and billed it as “the perfect choice for projects that require high performance decorative timbers with a natural appearance”. Cladding is a particular target and Arch said it will maintain the “longevity of the aesthetic appeal” of the product in a range of timber species, including pine, spruce, larch, Douglas fir and western red cedar.

“The ingredients in Tanalith M wood preservative were selected for their efficacy and formulated to meet the challenge of protecting timber’s visual appearance as an additional benefit,” said Janet Brown, marketing manager for Arch Timber Protection. “We’ve tested Tanalised Clear pressure-treated timber in realistic field conditions with appropriate species for European markets to provide a new product for specifiers.”

Arch said Tanalised Clear gives a 30-year service life for some applications and can block development of non-destructive staining fungi. These are commonly associated with untreated larch cladding, for example.