High gloss finish: The impact of surface roughness on gloss

Abstract

The cured finishes always contain certain irregularities that result from the technique and conditions of application. For this reason, in order to achieve smooth high gloss finished surfaces, it is necessary to polish ('rub-out') surfaces coated with high gloss finish. Rubbing means sanding the finished surfaces with very fine abrasive grits. In this paper we explored how each phase of the polishing process affect the surface roughness and the gloss of coated surface. The surface roughness was expressed by the parameters: Ra, Rz and Rt, and the gloss was determined by reflectometer (measurement angles 20˚ and 60˚). The results showed that through the stages of polishing, surface roughness decreased, while gloss of finished surface increased. The high value of the coefficient of determination (R2 = 0,984) indicated the linear dependence between the roughness parameter Ra and gloss of finished surface (at measuring angle of 60˚). The comparison of gloss results obtained by two measuring angles, confirmed the need for using the angle of 20˚ when determining the gloss of high gloss surfaces, since universal angle of 60˚ did not provided insight to small differences in the gloss that appeared as a result of polishing.