Physical Changes in Wood due to Thermal Modification

4 Physical Changes in Wood due to Thermal Modification 5.4.1 Colour 

Mitsui etal. (2003) studied the colour change of wood that had been previously irradiated with light and then subjected to a relatively mild heat treatment (no higher than 90 °C). The extent of colour change was dependent upon the wavelength of irradiation and was found to be considerably greater when the irradiated wood was heated under conditions of high humidity. 

Heating of wood results in a reduction in mass and a decrease in volume, the extent of which is dependent upon the treatment method, temperature and time of exposure (Seborg etal., 1953 Stamm, 1956 Rusche, 1973b Fung etal., 1974). The effects of different treatment parameters upon mass loss are summarized in Table 5.1. 

Lower rate of mass loss Higher rate of mass loss 

Furthermore, at this temperature the change in mass stabilized after about 30 minutes heating in the closed system. 

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