Coatings for Use on Wooden Bicycle Frames – Applicability, Test Methods and Artificial Weathering Results

Seven different coating systems were tested regarding their suitability for application on bicycle frames made of wood. Since bicycles are ridden throughout the year, the coating system has to withstand different outdoor climate conditions and, especially in winter, the salt brines from the roads. For this reason, an artificial weathering test with an additional freezing step was performed, followed by a specially developed salt brine spray test in ambient outdoor winter climate. Another focus was on the applicability of the coatings. For the tests, a range of coatings, originally developed for wooden front doors, floors and for boat building, was selected. These coatings were expected to meet the main requirements for UV radiation - permanence, weather resistance and saltwater firmness. The main constituents of the coatings were water-based polymer dispersions, two-component polyurethane systems or synthetic and natural oils. The layer thicknesses of the coatings, as well as colour and gloss data of the specimens, were recorded and rated. The adhesion capability was examined by carrying out a cross-cut-test. Surface damages were observed visually. It turned out that colour and gloss change served as good indicators for the decay of the coating. Three different coatings passed the accelerated weathering test. Salt spray had no significant effect on any of the coatings.