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Application of a model for the prediction of fungal degradation of thermally modified beech timber by Trametes versicolor
2013 - IRG/WP 13-40622
Colour measurement technology is found to be feasible for characterization of the property changes of thermally modified timber (TMT). In opposite to time-consuming and expensive laboratory tests a non-destructive test represents an improvement for the manufacturer of TMT. Therefore the aim of this study was to develop a method which allows sorting the different treatment intensities after the manufacturing process separately from each other, so as to help the manufacturers to ensure product quality. For TMT of beech wood a correlation of process-related decrease in mass to L*b*-colour-values was proved. Furthermore, linked to higher treatment intensities the fungal-related mass loss of TMT decreased. Fungal tests with Trametes versicolor indicated that the individual changes of the specimens need to be considered during the sorting of the durability classes. Therefore the development of the method of quality assurance is not directed to the production batches and thus determined averages, but by correlations of the parameters. With a selected model, parameters, e.g. durability, were calculated as a function of colour values. But the prediction of durability classes of TMT, based on colour values was feasible only to a limited amount of samples. The prediction of a durability class 2 or 1 seems to be feasible for treatment intensity of temperatures ≥ 220 °C.
Clauder, L., Richter S., Unger, W., Pfriem, A


Colorimetric evaluation of three tropical woods after accelerated weathering
2014 - IRG/WP 14-20541
The use of wood in the furniture industry is directly associated with their physical, mechanical and organoleptic characteristics. The color of the wood is a major factor in the selection of forests species to employ in the furniture projects and is fundamental the maintenance of its colorimetric pigments over time. The objective of this study was to evaluate the colorimetric behaviour of three tropical woods used in the furniture industry forward to accelerated weathering. The woods of cumaru (Dipterix odorata), marupá (Simarouba amara) and tauari (Couratari sp.) were selected and fifteen samples of each were produced at dimensions of 5 x 20 x 315 mm (thickness x width x length). The artificial accelerated weathering was conduced according to ASTM G 154 (2006) and the procedures used five cycle intervals of 240 hours of exposure up to a total of 1,200 hours in a climatic chamber. The colorimetric assessment was performed with a espectrophotocolorimeter, with D65 illuminant and 10˚ angle at room temperature and the CIEL*a*b* color space system was employed (1976) with ASTM D 2244 ( 2009) for the total color variation. The cumaru wood presented the lowest colorimetric variation followed by tauari and marupá. It was observed that the red and yellow pigments significantly decreased in the first cycle of 240 hours of exposure in all woods, and their surfaces got greyish. However, the renewal of surfaces were noted by the decrease of the total variation in color due to the leaching of photodegraded products, tending to return the their original colors.
R Faustino Teles, A Florian da Costa