SELECTED ASPECTS OF THE REACTION BEECH WOOD

The specifics of reaction beech wood in terms of basic chemical properties, colouration and dimensional properties of the wood fibres are presented in the paper. The samples of reaction and opposite beech wood were evaluated using standard chemical analyses by means of measuring the colour coordinates L*, a* and b* and determining the dimensional properties of the wood fibres using Fiber Tester. A well-known fact that reaction wood has a higher proportion of cellulose and a lower proportion of lignin than opposite wood is confirmed by the chemical analyses. The content of extractives in both samples was very similar (from 2.97 to 3.53%). The lightness (L*) of reaction wood is higher than the lightness of opposite wood, both in wet and dried wood. After the drying process, the lightness of wood increased slightly. The biggest colour differences were noticed between the wet reaction and opposite wood (Delta E* =18.6). Except one sample, all observed values of the total colour difference were Delta E* >3. Knowledge about well-recognized colour changes in wet reaction wood could also be applied in the early identification of reaction wood in the industrial practice. Based on the fibre length distribution, the fact that reaction wood contains fewer parenchyma cells alongside with the higher representation of fibre cells and the lower representation of vessels can be concluded.