The effects of continuously wetting-drying cycles on pre-weathered and oil-coated rowan (Sorbus torminalis) wood

Abstract

The naturally weathered and then oil-coated (Teak oil) Rowan wood (Sorbus torminalis) was subjected to distilled (A) and swimming pool water (B) aging treatments with continuous wetting-drying up to the third cycle. Treatment conditions and water aging types seem to influence color variables somewhat. The highest lightness (ΔL*), redness (Δa*), and yellowness (Δb*) changes were measured in samples that were continuously aged at the third cycle procedure in swimming pool water, respectively. Similar results have also been observed for total color changes, such that pool water had higher discoloration effects on color values compared to distilled water at similar conditions, while increasing the cycle usually further lowered discoloration. The highest color change value of ΔEB3: 10.49 (metric) was found in the third cycle in pool water treatment, followed by a value of ΔEB2: 9.42 (metric) in the second cycle and a value of ΔEB1: 1.71 (metric) in the first cycle, respectively. Color changes could be employed as a sensitive physical indicator of coating aging, which can be correlated to the associated chemical changes. All aging processes have lower gloss values than control in all aging procedures, regardless of water type. The lowest gloss value of 1.2 GU was noticed at the third cycle in swimming pool treatments. It is also notable that the most dramatic effect on surface hardness (Shore D) was found after the first cycle, while the lowest hardness values of 38 (metric) and 33 (metric) were found in swimming pools and distilled pure water-treated samples, respectively.