Peracetic Acid Treatment as an Effective Method to Protect Wood Discoloration by UV Light

Wood has always been used for various day-to-day applications such as interior or exterior construction materials, and household products. However, it can undergo photodegradation and discoloration by environmental factors including ultraviolet (UV) light, and thus has shortened its service life. Bleaching or delignification of wood surfaces is a suitable solution to stabilize wood against weathering by UV because these techniques can alter or remove the chromophores in lignin, which is a main factor of wood discoloration. To improve the color stability of wood surface according to the lifespan, surface delignification was conducted using peracetic acid (PAA) and hydrogen peroxide (HP) on the woods of Larix kaempferi and Quercus mongolica. After the PAA treatment, L* increased considerably from 60–70 to 90–95. Furthermore, wood surface color did not change significantly after UV exposure. The color differences (ΔE*) between before and after PPA treatment of wood showed the 4.8–12.2 of L. kaempferi, and 1.7–3.7 of Q. mongolica, respectively. The lignin-related peaks in Fourier transform infrared spectroscopy (FT-IR) spectra disappeared with increased duration of PAA treatment. These results confirmed that the lignin component was partially or completely removed after the PAA treatment; the color differences (ΔE*) clearly showed that there was a reduction in redness (a*) and yellowness (b*), and an increase in lightness (L*) owing to the removal of lignin. Based on these results, this study demonstrated that the partial removal of lignin from wood surfaces is a fundamental method for resolving photo-degradation.