Effect of machined profile, zinc oxide and titanium dioxide particles on checking southern pine deck boards during weathering

The aim of this research was to test the hypothesis that the combination of profiling, treatment and a surface coating with nanoparticles will be effective at reducing checking in deck boards exposed to the weather. In this study southern pine (Pinus sp.) deck boards were machined to flat (control) and ribbed surface profiles. The specimens were treated with aqueous copper amine azole (CA-C) using a vacuum/pressure method and coated with nano-ZnO and micronised TiO₂. Boards were exposed to accelerated weathering for 576 h. The number, length and width of checks that developed in the boards were quantified and the average amounts of cupping, twist and bowing occurring in the weathered wood were examined. The results of the statistical analysis showed that all of the coated ribbed decking samples had lower average check numbers, lengths and widths compared to the end-matched flat untreated specimens. Checks were also shorter and narrower in the profiled southern pine deck board than in the unprofiled specimens. Furthermore, the lowest amount of cupping, twist and bowing were observed for specimens profiled and coated with the TiO₂. Therefore, the authors conclude that the coated ribbed decks looked significantly better than the flat decking.