Effect of outdoor exposure and bleaching on surface color and chemical structure of scots pine

This study was carried out in order to investigate the changes on chemical structure and surface color of scots pine (Pinus sylvestris L.) after exterior conditioning followed by bleaching process. Specimens were first exposed to exterior conditions for 12 months, and then bleached with three different solutions: 18% NaOH + H2O2, NaSiO3 + H2O2, and CaOH2 + H2O2. Afterwards, specimens were re-exposed to exterior conditions for 12 months. Measurement of color differences and changes in chemical structures of finishing after the process of exposure to outdoors and bleaching were made according to the ASTM D-2244 standard. As a result, it was deduced that exposure to exterior conditions causes color differences in specimens while bleaching with given solution groups reduces that affect and reverts the surface color to that of natural control specimens. However, specimens exposed to 12 months exterior conditioning had more discoloration than that of natural control specimens. This finding leads to a conclusion that in restoration of uncoated or unfinished wood exposed to exterior conditions for 12 months, bleaching process could increase service and economic life of material.