Effect of substrate and number of coats on solar reflectance measurement of inks

Abstract

Solar reflectance is a property that influences the thermal performance of buildings. In this work, the influence of four substrates and the number of paint coats on the solar reflectance of the surface was evaluated. To carry out the tests, three spray colours were selected (white, silver and green), applied to four substrate (ceramic, fibre cement, aluminium and sandpaper). The method was organised into: preparation and painting of samples, measurement of solar reflectance and analysis of results. The solar reflectance verification was determined based on the ASTM E903 standard and the use of a spectrophotometer UV-VIS-NIR. The samples were evaluated in the natural surface condition (unpainted) and with paint application (one, two and three coats). The results show that the number of coats applied to the surface and the type of substrate significantly affect the reflectance result. Considering all the samples analysed, the maximum absolute variation from the first to the second coat of paint reached 0.35, and from the second to the third coat 0.19.