Influence of Combined Hydro-thermal Treatment on Aestetical Propriertes of Turkey Oak (Quercus cerris L.).

Turkey oak (Quercus cerris L.) is one of the most widely distributed species along the Apennines in the Southern Italy. However a less technological quality maintains this kind of wood principally for energy destination. Moreover, chromatic differences inside the wood structure are much more evident than in other species, with a quite white sapwood and a dark grey heartwood, frequently accomplished by a presence of black heart. The aim of this research was to evaluate the possibility of reducing aesthetical limiting factors of Turkey oak. This was made by investigating on the combined effect of steaming treatment (in an autoclave) and heat (in a oven) on green wood of Turkey oak. Specimens without any defects were used for the tests. Sapwood and heartwood of samples were also separated. Steaming treatment was carried out for 2-6 h at 100°C, 120°C and 135 °C and then the same samples were used for a heat treatment for 2 h at 120 and 180°C. Colour change of the wood specimens was tested in comparison with untreated ones. The colour results were given in the CIE L*a*b* colour co-ordinate system. In addition, spectral reflectance measures were obtained by using a spectroradiometer provided with a plant probe, in the range between 300 and 1.100nm of the electromagnetic spectrum. It is shown that significant colour changes could be obtained by using combined hydro-thermal treatment. With rising temperature the colour change of wood was higher. Turkey oak wood was more sensitive to the steaming temperature at 135°C combined with heat treatment at 180°C. Intermediate treatments assured more reliable results on homogenization of hue, while treatments at “ST100+H180” and “ST120+H180” highlighted noticeable results for lightness. In terms of colour spectra, the combined effect between steaming and heat treatment at 120°C seems to be moderate. Such treatments could lead to improve aesthetical properties.