Synergistic contribution of bio-based additives in wood paint: The combined effect of pigment deriving from spirulina and multifunctional filler based on carnauba wax

This work aims to reveal the synergistic behavior of two bio-based additives on the durability and protective behavior of a bio-based wood paint. The powder extract form spirulina was introduced as a natural pigment, while carnauba wax was used as a multifunctional filler. The impact of the two additives on the morphology of the coatings was investigated by scanning electron microscopy observations, while their role on the durability of the paint was assessed by exposing the samples to UV-B radiation and continuous thermal shocks. Infrared spectroscopy analysis, colorimetric inspections, adhesion test and scanning electron microscope observations were employed to investigate the impact of the synergic behavior of the bio-based additives. Furthermore, the role of the spirulina and wax powders on the barrier performance of the coatings was evaluated by liquid resistance test ad water uptake test. Finally, Buchholz hardness indentation test and the scrub test were employed to estimate the effect of the additives on the mechanical properties of hardness and abrasion resistance of the coatings. Ultimately, this work demonstrates the interesting synergy of spirulina and wax, able to provide an intense coloring and certain aesthetic features to the paint, to improve the water-repellent properties of the surface and to increase the abrasion resistance of the composite layer.