The influence of the impregnation process of pine wood (Pinus sylvestris L.) samples on the electrical resistance changes and the moisture-content measurement accuracy is presented in this paper. In this study, the resistances of impregnated and nonimpregnated green pine timber harvested from northern Poland were compared. An impregnation method based on a vacuum-pressure chamber was used. Copper salts were applied as the impregnated solutions. The obtained results of the electrical resistance comparison showed a dependence of wood resistance on the moisture content. Higher conductivity occurred in impregnated wood samples filled with copper salt compared with wood samples without impregnation. Noticeable differences in the electrical resistance values were observed when the wood moisture content was significantly above the Fibre Saturation Point (FSP).

Structure of wood can affect intensity of color change in remarkable ways. This article was focused on the analysis of the color changes red false heartwood and mature wood by different methods such as ΔE* (Total color difference), h* (Hue angle), C*_ab (Color saturation) and S_ab (Saturation). The aim of this study was to evaluate the color properties of red false heartwood and mature wood by using different chromacity coordinates. Our observations suggested that the density in the absolute dry state was equal between the red false heartwood and mature wood. The biggest difference was in the area of the free water domain, thus from an initial MC value to the fiber saturation point (FSP). The shorter drying time of the red false heartwood samples was caused by their lower initial MC. Due to the different MC, the temperature created a different color intensity of the compared samples. Mature wood samples achieved more saturated color in the drying process than did the samples of red false heartwood.

The cost of raw materials has a major role in the wood industry. From this point of view, it is necessary to pay attention to the correct log-sawing pattern, which will optimize the sawing process and increase the quantity and quality of the material as well. For measurements, we used beech wood (Fagus sylvatica L.). Beech wood (Fagus sylvatica L.) is the most common wood species in the Slovak Republic; the total amount in forests is 34.8%. Beech wood has a high frequency of defects, such as red false heartwood, reaction wood (i.e., tension wood), dote, cracks, and so on. This research aimed to analyze the effect of the log-sawing patterns of through-and-through sawing, cant sawing, and quarter sawing on the resulting quantitative–qualitative yields of beech timber. The results showed that the highest quantitative yield was observed with the cant sawing pattern, at 84%, which was, on average, 17.3% higher compared to other types of cutting. It was found that quarter sawing resulted in a higher qualitative yield compared to through-and-through sawing or cant sawing (V₅ = 62.69% and V₆ = 47.86%).

Determining the Influence of Sample Thickness on the High-Temperature Drying of Beech Wood (Fagus sylvatica L.)

The thermal treatment of wood changes its structure due to the degradation of wood polymers (cellulose, hemicellulose and lignin), so the physical properties of wood are either improved or degraded. Color changes apply not only to natural wood, but also to such wood composites for which some amount of glue is used in their construction (e.g., plywood, blockboard or laminboard). This article is focused on the analysis of hornbeam and field maple wood color changes influenced by drying temperature. Two types of drying modes were used: hot-air mode where the temperature of the drying environment was 60 °C, and high-temperature mode with a drying temperature of 120 °C. The drying mode was divided into two phases depending on the moisture content of the wood. The compared woods had similar values of color coordinates at the beginning of drying. During hot-air drying, the largest changes in color coordinates occurred during the first 24 h. The total color difference between the color at the end and the beginning of drying was 7.3 for hornbeam and 11.1 for maple. The overall color difference between the compared woods was minimal. During high-temperature drying (120 °C), the color changes of the dried woods were more pronounced. In the case of maple wood, there was a very significant change in color and the value of ΔE* was twice as high as for hornbeam. The total color difference between the color at the end and at the beginning of drying was 8.7 for hornbeam and 18.9 for maple.

The bark as a product of the dividing of wood and cork cambium consists of a set of protective layers of cells, which protect the living tissue (cambium) from the external environment and separate the bark from the wood. The structure of bark as a component of a living tree is completely different from wood. This article describes the testing of the adhesion of wood/bark in the longitudinal and tangential anatomical direction during the dormant and growing season on three choice wood species (oak, beech, and spruce). The results show a remarkable influence of the wood species and anatomical direction, as well as period of vegetation (dormant or growing season). All wood species had higher values of shear strength in the longitudinal direction compared to the tangential direction. The highest average values in the longitudinal direction were measured in the dormant period for sessile oak (0.49 MPa) and beech (0.48 MPa). The lowest value of shear strength in the longitudinal direction was measured for spruce (0.36 MPa). During the growing season, the highest average shear strength values were also measured in the longitudinal direction at beech (0.46 MPa) and oak (0.39 MPa). The lowest value of shear strength in the longitudinal direction was measured similarly for spruce (0.26 MPa).