Investigation of pH effect on color and surface roughness of walnut veneer

This study aimed to examine the walnut coating which has a wide range of applications in the living spaces may be exposed to acidic and basic cleaning products that may occur the color and morphological changes. The effects of hydrochloric acid (HCl) and sodium hydroxide (NaOH) solutions prepared at different pH values on the surface roughness and color properties of walnut wood veneer sheets were investigated. The walnut veneer boards were exposed to acidic pH (1.5, 3.0, 5.0) and basic pH (8.0, 11.0 and 13.5) solutions for 10 min. Surface roughness measurements of boards were performed according to ISO 4287, color measurement analyzes according to ISO 2469 standard. According to the obtained results, the values of surface roughness parameters (Ra, Rz and Rmax) of the walnut veneer boards decreased as the pH value was decreased in both acidic and basic media. In color measurements, it was determined that the degree of yellowness increases as the pH value decreases in acidic and basic medium. While the whiteness and brightness levels were not affected in the acidic medium, it was found that the whiteness and brightness were increased in the basic medium as the pH value increased