
 Possibilities for compositional tailoring of Norway spruce (Picea abies
 L. Karst.) wood using a hydrophobic oil impregnation process

ZusammenfassungImpregnation with hydrophobic oils offers non-toxic options for preserving Norway spruce (Picea abies L. Karst) wood that could potentially be used to tailor the properties
 of wood products, especially those used in exposed conditions. The objective of this study was to quantify
 the effects of the water-filled porosity and density of Norway spruce wood and treatments (applied to set
 the wood’s water contents at desired test levels) prior to impregnation with the linseed oil derivative
 Linogard by the Linotech process on its oil retention. Retention of oil differed significantly between
 tissue types. Dried specimens always retained less oil than corresponding undried or rewetted specimens.
 Furthermore, water-filled porosity and density had significant effects on oil retention levels within tissue
 types, allowing linear regression equations to be developed that gave good predictions of oil retention
 parameters for different tissues, with R2 values ranging from 0.66 for mature
 heartwood to 0.85 for mature sapwood. Thus there is scope to use hydrophobic oil impregnation processes
 for producing compositionally tailored wood materials with specified properties.

Moisture sorption and swelling of Norway spruce [Picea abies (L.) Karst.] impregnated with linseed oil
Abstract The moisture sorption and swelling of spruce specimens impregnated with linseed oil and unimpregnated controls were studied in two sorption experiments: from 0 to 55% relative humidity (RH) and from 55% RH to water saturation. Sorption isotherms were also determined using a sorption balance. The impregnated specimens had lower rates of both moisture sorption and swelling than the unimpregnated controls; however, there was no significant difference in final moisture contents. In addition, the linseed oil impregnation did not improve the dimensional stability of the wood; in most cases the specimens impregnated with linseed oil swelled more than the unimpregnated controls. For the impregnated specimens, reductions in swelling rates were in most cases seen without corresponding reductions in final swelling. The moisture sorption rate was reduced for the impregnated specimens but there were generally no reductions in equilibrium moisture content.
Hygroscopicity of wood impregnated with linseed oil
SummaryThe reduction in hygroscopicity as spruce wood is impregnated with linseed oil may be accounted for using a molecular exclusion model. On the basis of the model, each linseed oil molecule appears to displace 90 water molecules and occupy 6 hydrogen bonding sites in the wood.