Uptake of chitosan based impregnation solutions with varying viscosities in four different European wood species

The uptake of chitosan based impregnation solutions were tested on Scots pine (Pinus sylvestris L), Beech (Fagus sylvatica L.), Downy birch (Betula pubescens Ehrh.) and Norway spruce (Picea abies L. Karst.) in longitudinal, radial and tangential directions separately. The four chitosans tested had a fraction of acetylated residues (FA) of 0.198 and average molecular weights ranging from 18 to 129 kDalton. The kinetic viscosity of the 2.4% (weight/volume) solutions at pH 5.0 was in the range of 2.95 to 28.8 mm(2)s(-1). The general trend showed that there was an increase in uptake of chitosan based impregnation solutions with decreasing viscosity, and the chitosan solution with the lowest viscosity had almost comparable uptake with water for Pine and Beech in the longitudinal direction. In general, the lower the ability for uptake of impregnation solution, the more the viscosity influences the uptake.