Study of industrial boiling process on walnut colour: Experimental study under industrial conditions

Wood color evolution during thermal treatment is not well known. No experiment before was conduced for studying the wood color under industrial process. This paper describes color transforming of four walnut (Juglans regia) logs, measured during boiling water process under industrial conditions. The colour changes in sapwood and heartwood evolution were analysed according to the previous results obtained in laboratory. As it was expected, the sapwood color changes quickly during the first 10 hours and definitely after 30 hours of industrial treatment. Its colour is darker and redder. Heartwood behavior is quite different because its colour is changing slowly during the first 10 hours and important changes are occuring after the 39 first hours. These mean results were obtained on the four logs studied. This work precise the particular behavior of the color of wood during boiling and the efficient method used. This study may be used by industries, which are concerned by heating treatment before slicing, and applied to other species.