A direct method of measuring the pH value of wood substance is proposed in the paper. The achieved results were completed by determining the pH value on the wood surface using the contact method. Moreover, the results were compared to the results achieved using the indirect methods to determine the pH value in cold water, as well as hot water, extract of wood. Using the direct method for measuring the pH value in drilled fresh sawdust, the pH value of beech was 5.11, of birch was 5.29, of alder was 4.88, and of maple was 4.65. Following the achieved results, the possibility to measure the pH value using a fast, accurate method useful in practice complying with the condition of the minimum free water in wood (moisture content of wood above the fibre saturation point) was presented. The results of measurements of the pH value using the contact method on the wood surface showed that this method can be used in the case of coniferous as well as broadleaved trees with heartwood. The value of pH measured on the surface of pine was 4.50, of spruce was 4.79, of the heartwood of oak was 3.46, and of the sapwood of oak 5.04. The measurement of pH values of water extracts confirmed great dependence of measured values on the conditions of wood extraction.

The aim of this work was to evaluate the changes of the chemical components in birch wood (Betula pendula Roth) caused by steaming with saturated steam at three temperatures—105 °C, 125 °C and 135 °C. In the samples of the original wood and wood after steaming, select chemical characteristics were determined, and wood, isolated holocellulose and Seiferts’s cellulose were analysed by attenuated total reflectance Fourier transform infrared (ATR-FTIR) spectroscopy. The greatest changes in the birch wood characteristics were observed in steaming mode III (135 °C). The differential spectra of the birch wood samples indicated that the hemicelluloses were significantly degraded and that the dehydration reactions were able to proceed. A clear increase in both unconjugated and conjugated carbonyls was seen only in mode III. The findings also confirmed the greater sensitivity of the guaiacyl lignin contained in broadleaves to elevated steaming temperatures, as well as the course of the thermal oxidation reactions and the formation of new carboxyls in mode III. The decrease in the ratio of absorbances H 1732/2900 and H 1243/2900 demonstrated the cleavage of acyl (acetyl and formyl) groups from birch wood hemicelluloses. The qualitative and quantitative changes of the hemicelluloses and extractive substances in birch wood during steaming were well-correlated with the measured pH values and wood colour.

An engineering approach for the calculation of the specific mass energy consumption, which is needed for defrosting and the subsequent heating of the frozen wood chips above the hydroscopic range, (in kWh·t-1), has been suggested. Equations for easy calculation of have been derived, depending on the wood moisture content u, on the fiber saturation points of the wood species at 20 °C and at –2 °C (i.e. at 293.15 K and at 271.15 K), and respectively, on the initial chips’ temperature, T0 , and on the final temperature of the heated after their defrosting chips, T1.For the calculation of the according to the suggested approach and equations a software program has been prepared in MS Excel 2010. With the help of the program calculations have been carried out for the determination of the energy consumption , which is needed for defrosting and subsequent heating of oak, acacia, beech, and poplar frozen chips with moisture content in the range from u = 0.4 kg·kg-1 to u = 1.0 kg·kg-1, initial temperature t0 = –20 °C and t0 = –10 °C until reaching of the chips‘ mass temperature of t1 = 80 °C, t1 = 100 °C, and t1 = 120 °C at the end of the heating.

Changes in maple wood’s pH and color (Acer pseudoplatanus) were evaluated before and after thermal treatment process with saturated water steam. Maple wood was thermally treated at temperatures: tI = 105 ± 2.5 °C, tII = 125 ± 2.5 °C, and tIII = 135 ± 2.5 °C for τ ≤ 12 hours. Direct pH measurement of maple wood with a moisture content above the fiber saturation point (FSP) was performed using a pH-meter SI 600 with a Lance FET + H puncture probe. The polynomial dependence of pH and total color difference ∆E* on temperature t time τ was calculated by statistical processing of measured results. The correlation between the total color difference ∆E* of maple wood in the process of thermal color modification and the pH value is expressed y the equation: ∆E* = 4.5516∙(pH)2 – 48.405∙(pH) + 134.35. This dependence is a suitable tool for assessing the achieved color change based on the change of wood pH in the technological process.

Light, primarily its more energy-rich component - near ultraviolet radiation, causes gradual degradation (ageing) of paper and other organic based materials. The objective was to determine selected characteristics of the changes of white office paper, which occur under intensive ultraviolet treatment, and to calculate their light fastness, as this is an important functional feature for the number of papers. The most visible sign of paper ageing is the change of its optical characteristics. The value of specific lightness decreased by 2.2%, red / green coordinate a* moved from the red region (1.5) colour space to green (-0.8), b* coordinate moved from the blue region (-8.4) to yellow (4.7) and colour difference ΔE* reached 13.4 during 120 minutes' exposure. The pH values of paper surface gradually decreased with time of UV exposure from 8.86 to 7.91. Effects of light also deteriorated the selected mechanical characteristics of paper, such as breaking length and tear index. Out of the monitored properties, the specific lightness of paper surface showed the greatest stability (97.8%). UV radiation most affected breaking length of paper whose stability was only 79.4%.