Edinburgh Napier University

  Distortion (warping) when sawn timber is kiln-dried has been identified as the most important quality barrier preventing the wider utilisation of UK-grown timber in the construction industry. Using more timber in new buildings would not only add value to the UKs forest resource but would also lock up substantial amounts of carbon in permanent structures.
Wood shrinks in all directions on drying. Longitudinal shrinkage is least, but if it is at all uneven across a piece of timber then the timber will bend or twist (Backstrom & Kliger, 2006). Longitudinal shrinkage depends on the angle that the wood cells make with the tree (Schulgasser et al, 2007) and on the angle that the cellulose microfibrils make with the wood cells (microfibril angle, MFA). The quantitative details of these relationships are not clear (Yamamoto et al, 2001). There is now a large body of knowledge on the effect of cellulose orientation on wood stiffness and it would be very helpful if some of this knowledge could be utilised to predict longitudinal shrinkage and distortion.