Ceramic technology. How to investigate surface finishing

Abstract

Surface treatment techniques, that is, smoothing and burnishing, help to define the cultural, traditional, and economical state of an ancient society. They prove artistic feelings combined with practical skills were used to obtain more attractive and highly functional objects. This paper aims to prepare the reader to investigate ceramic surfaces and discern between different treatments. Interpretation of the finishing techniques is based mainly on a wide variety of surface topography. Both treatments plastically deform the surface and tend to diminish its roughness, but the results are strikingly different. A smoothed surface has still large irregularities and a dull or matte appearance due to the diffuse reflection of light. A burnished surface has only small-sized irregularities and is glossy/lustrous due to specular reflection of light. Smoothing slightly aligns the platy minerals only at the very surface, whereas, burnishing may create two separate individual levels: A burnish peel and a subsurface layer. The differences are evidenced by all applied analytical methods, such as macroscopy, optical microscopy, electron microprobe, scanning electron microscopy, and vertical scanning interferometry.