The treatability of Scots pine (Pinus sylvestris) sapwood is ranked in the European standard EN 350-2 as class 1 (easy to treat), although huge differences in sapwood penetration exist. To obtain full sapwood penetration, process parameters have to be adjusted to the material most difficult to treat. It is therefore of importance to understand the factors that are responsible for penetration differences.
Scots pine sapwood was investigated for anatomical differences influencing the ratio of filling (RoF) when treated with the wood modifying agent furfuryl alcohol. The database for the study was samples from two test series including Scots pine from Norway and Denmark. Within these experimental series each sample can be reassigned to its original position in the stem. The RoF for each sample was evaluated, and the variation in treatability within trees, between trees and between different stands was studied. Latitude was found to be the single factor influencing the treatability most. Within the trees, the treatability of sapwood increased with distance from ground and with distance from the heartwood boarder.
In a subsequent study dendrochronological software was used to measure the rates of earlywood and latewood, to calculate the average latewood content. A multivariate data analysis described the latewood content as a significant contributor which correlated positively to RoF. A negative correlation between latitude and average latewood content in the different stands was found. In addition, the chemical composition, including lignin, holocellulose, ash and extractive content of the samples was investigated using thermogravimetric analysis in order to evaluate the influence of wood composition on the RoF. Wood composition was found to be unchanged even for samples with a large difference in RoF.
Keywords: furfuryl alcohol, latewood content, latitude, RoF, Scots pine sapwood, treatability, wood composition
Authors
Zimmer K.
University of Hamburg; Section Wood Technology; Norwegian Forest and Landscape Institute, Ås, Norway
Larnøy E.
Section Wood Technology, Norwegian Forest and Landscape Institute, Ås, Norway
Koch G.
Institute of Wood Technology and Wood, Johann Heinrich von Thünen Institute, Hamburg
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