Surface Roughness and Color Change of Copper-Amine Treated Red Maple (Acer rubrum) Exposed to Artificial Ultraviolet Light

Summary

UV absorbers were microwave-grafted onto copper-amine (Cu-MEA) treated maple. The so-treated wood was weathered with UV light for various periods of time. Two weathering cycles were used: one with only an irradiation step using a 175W medium pressure mercury lamp of wavelength higher than 300 nm and a second with irradiation and a water spray step. The surface color and the surface roughness were monitored and the biological performance of the UV absorbers grafted on copper amine-treated maple evaluated as well. ∆E, the total color change was measured and it increased from 0 to 14.7 after 317 h weathering for untreated maple. For Cu-MEA treated and UV absorbers grafted on the surface, the values of ∆E range from 0.7 to 5.7. The higher values of ∆E for both treated and untreated samples were associated with the weathering cycle with the water spray step, suggesting that water plays an important role in the wood discoloration. However, the microwave grafting of UV absorber on Cu-MEA treated maple did not prevent or reduce the formation of rough surface or inhibit the biological performance of Cu-MEA. This laboratory study indicates that phenolic UV absorbers can be microwave grafted on maple to improve the color stability.