Nexfor – a £1.2bn company with operations in Canada, the US and the UK – started making OSB more than 20 years ago, and acquired its Inverness site in 1998.
Sterling OSB from Inverness is made from locally grown plantation timber, mostly pine and some spruce, and is fully Forest Stewardship Council (FSC) certified.
The product is manufactured in thicknesses from 9-25mm, with thicker panels possible. Sales director Maurice Fitzgibbon says: ‘Sterling OSB is manufactured in an engineered way that produces panels with predictable properties time after time.’
OSB evolved from Waferboard which was first developed in 1954 by James D’Arcy Clarke. The aim was to preserve large valuable lumber and use small roundwood to produce a viable building panel. The first true OSB was produced in 1982.
Much of the timber used to manufacture Sterling OSB at the Inverness plant comes from the nearby Cawdor Estate in the Highlands. The 60,000-acre estate, which is FSC certified, has around 13,750 acres of woodland made up mainly of productive commercial plantations.
In the region of 25,000 tonnes of timber are harvested each year, either manually or by machine. Much of the timber is used by John Gordon & Son of Nairn, with the least added value part of each felled tree destined for Nexfor.
The company maintains that because OSB is made of a material that really has no other use, it makes it extremely environmentally friendly.
At the factory the logs are cut to length, debarked and processed into precise strands measuring 78mm long and 25mm wide. These are dried, blended with resin blender and wax and laid in a precisely oriented fashion to form large continuous mats.
The strands are oriented in cross directional layers for increased strength and bonded with moisture resistant resins under high heat and pressure.
Bark that is stripped off is either burnt for heat or sold to the horticultural industry. The logs then go through a metal detector before passing into a flaking machine which has 48 knives and rotates at 400 revolutions a minute. The knives have to be changed every six hours.
The strands are coated with resin and wax in blending drums before creating a surface layer and core layer for each mat.
The mats are heated and pressed and then checked for ‘blows’ – an indication they contain too much moisture. Each mat is marked with the date and time of its manufacture and certificate details, and when sawn it is to 2mm accuracy.
Ninety seven per cent of each panel is wood from a sustainable source – the rest is wax and adhesive – and Nexfor uses between 1,000-1,500 tons of logs a day.
