Applied science

Summary
• Research aims to improve Sitka timber quality to construction grade.
• Acoustic testing is proving itself in the field.
•There are opportunities to increase timber cladding’s market share.
• Next year’s conference will be held at the Centre for Innovative Construction Materials at the University of Bath.

Geoff Taylor’s pledge to return the Institute of Wood Science (IWSc) conference to its scientific roots during his presidency took form at the end of November with speakers at this year’s event covering subjects such as volatile organic compounds and acoustic testing of Sitka spruce.

This year’s venue, Edinburgh Castle, was a fitting location for such a conference as one of the city’s universities, Napier, has become, in Mr Taylor’s words, “a centre of excellence for wood science”.

The first trio of speakers reinforced that view with an outline of the research being undertaken at Napier University into the extent of variation within Sitka spruce. The Strategic Integrated Research in Timber (SIRT) project is providing information that should enable the selection of better quality trees and timber. The ultimate goal is to see more British-grown material in timber frame construction.

Matching resource to demand

Dr John Moore, senior research fellow at Napier’s Centre for Timber Engineering (CTE), said the aim of his research was to “try to understand the characteristics of the resource and match them to users demands”. This involves discovering the influence site, silviculture, genetics and rotation length have on factors such as modulus of elasticity (stiffness), modulus of rupture (strength) and dimensional stability.

These three factors are crucial in determining whether a species reaches construction grade and, in Sitka’s case, it is modulus of elasticity (MoE) that generally consigns it to the lower C16 grade. “Around a 40% improvement in Sitka stiffness would be needed to make it C24 grade,” said Dr Moore, “something that should be possible through prudent forest management and silviculture.”

Dr Steve Lee, head of the conifer breeding unit at Forest Research, which is collaborating on the SIRT programme, described the field work that supports the laboratory testing. The aim, he said, was to “maximise value by satisfying the construction market”.

A visual judgement of a tree’s genetic quality is “very high risk” because of the influence of site and silviculture, said Dr Lee, but trees were generally selected for height, straightness and wood density.

The conifer breeding programme is proceeding rapidly, he said, adding that achievements to date include a prediction of 25% more volume at felling and up to 40% more top quality sawlogs at felling. “Eighty per cent of Sitka planted in Britain is now improved and new stock is now available which will further add to improvements of quality and uniformity,” he said.

However, he added, research needs to speed up and cost less and one of the new “tools” at their disposal to help achieve this is acoustics.

That’s an area of study for the CTE’s Andrew Lyon, who uses acoustic tools – “old technology in a new package” – to predict Sitka’s wood properties, thereby enabling it to be directed to the appropriate end use.

Acoustic, or stress wave velocity testing, has the advantage of being non-destructive because the quality of the timber can be predicted either before the tree has been felled or before a log is converted. Ongoing research involves further “destructive” testing in the laboratory to corroborate the field tests and validate the prediction method.

“The use of acoustic tools in Scotland is in its infancy,” said Mr Lyon, “but it’s rapidly caught up with the rest of the world and is now starting to lead the way.”

Fitness of purpose

The drive towards fitness of purpose has also had an effect on other wood product industries, as Geoff Rhodes, marketing and business development director of Coillte Panel Products, the manufacturer of Medite MDF and SmartPly OSB, pointed out.

It had led, for example, to the development of speciality grades of panel products, he said, adding that the sector had “good solutions for the construction industry”.

That message still has to be driven home, however. “We have a lot of the science to prove that the products fit, but we all need to understand the science more in order to be prepared to deal with issues such as the need to decrease carbon emissions. We need to have the confidence to bring the message to the market.”

He added that the sector had benefited from advances in press and BioComposites technology, but reminded delegates that the bottom line still had to be satisfied. “We need to develop products that can be sold commercially,” he said. “We need to translate innovation into commercial reality.”

The BRE’s director of timber research, Dr Ed Suttie, added that innovation could increase a product’s market share. The product he focused on at the conference, in a paper co-authored by Geoff Taylor, was wood cladding and, he said, innovations to improve its durability could improve its loosely estimated 3% share of the cladding market.

Timber cladding may not have met its service life expectations in the past, Dr Suttie said, but it could now, thanks to “fairly basic modifications to design to reduce the risk of moisture ingress” and to improvements in substrate selection, in fixing methods, in preservative and coatings technology and innovations in the field of wood modification.

“If we can get a dimensionally stable wood where the maintenance schedules can be stretched right out, it’s a real challenge to competing materials,” he said.

Need for knowledge

There was no doubting the depth of knowledge contained within the conference room but, sai, Peter Condon, “there’s not enough knowledge in our trade”.

Mr Condon, who works with Napier’s CTE, developing learning materials for the industry, and who specialises in online learning, said he had been “shaken by the lack of knowledge of the product” when he had visited sites.

“Our industry seems to be struggling with education,” he said. “If industry is going to put all the ideas [expressed in the conference] into practice, to move from innovation to application, then we have to explain the benefits – and more quickly.”

The answer, he said, was to reach individuals in their place of work and one of the ways to do that was by online education.

The IWSc has just taken a big step in this direction by putting its Foundation course online, but Mr Condon suggested more could and should follow. “If we’re doing such a great job, why are businesses writing their own courses?” he asked. “It’s not their prime purpose and it’s unrealistic to expect them to do it.”

The twin themes of knowledge and education will be central to next year’s conference, to be held at the new Centre for Innovative Construction Materials at the University of Bath on September 18-19, said Geoff Taylor. “Remember,” he counselled, “if the cost of education is high, the cost of not doing it is even higher.”