On the Relationships Between Topography and Gloss, 1990 Polymers, Laminations & Coatings Conference Proceedings

Gloss, while not precisely defined in the literature (1), is a function of a surface inherent reflectivity (2) and its’ diffuse reflectance (3,4). The latter property is primarily a function of its topography. Despite the fact that gloss and roughness are known to be inversely related, it has proved difficult to relate relative gloss to quantitative determinations of specific surface geometric characteristics. This study was undertaken to identify measureable surface geometric parameters that relate to gloss.

Using newly developed apparatus, statistical distributions of a number of topographic parameters were determined for three identically coated sheets, that differed only in topography and gloss. It should be noted that the factors affecting also relate to other practical paper manufacturing problems (5,6,7). These include print mottling, ‘orange peel’ gloss striations, coating graininess, ink density variations, coating mass variations, and gloss profile (5,6,7).

The topographical features giving rise to some of these effects have been reported to range in size from 1 micron to 1 millimeter (5). Their characterization therefore requires instrumentation able to quantitatively measure three dimensional topographical characteristics, in this relief range, at that scale, over relatively large areas. Indeed, as will be evident, the topographical characterization of these sheets and the identification of pertinent parameters related to gloss required lateral resolution in the micron range. It is hoped that future investigations will lead to the identification of other sets of parameters that prove useful in addressing some of the problems delineated above.