Surface properties include both surface roughness and friction. With a stylus-type contact method, it is necessary to obtain either a surface roughness profile or a friction profile that is affected by stylus shape and size, its contact force on the sample, the scan speed, and the data acquisition rate. As a new surface parameter, the mean absolute deviation (MAD) from an average property has been introduced. It represents the deviation from either the roughness average (Ra) and the average coefficient of friction (COF), respectively. While Ra or average COF depends on the instrument and its operating conditions, the MAD should not depend on them because it represents the variations within the sample.

A surface profilometry technique was used to characterize the surfaces of paper products. A stylus-contact type profilometer capable of simultaneously generating both surface roughness- and friction-profiles was used. As a stylus for the profilometer, a conical shape whose tip was rounded to have a 0.5 mm curvature radius was designed and successfully employed in both printing & writing (P&W) papers and hygiene papers such as bathroom tissues and kitchen towel. From the profiles, the mean absolute deviation (MAD) from the averages, i.e., R-MAD from the roughness average and F-MAD from the average coefficient of friction, were suggested as the new surface characterization parameters. To elucidate the surface roughness profiles by fractal dimension analysis, the variogram method was applied to get the fractal dimensions of the paper products. Generally, the value of the fractal dimension increased as the surface roughness increased. The surface profilometry technique with the fractal dimension analysis with the variogram method looks promising to gain additional insight on the surface characteristics of paper products.

Friction profilometry is a powerful technique that is suitable for the surface characterization of paper products. In this technique, a stylus-type contact method that resembles papermaking processes is used for evaluating the quality attributes of products. The surface characterization requires both surface roughness and friction measurements. At present, however, few reports have been available regarding characterization of the friction by the surface profilometric method. The objective of this study was to provide guiding principles of a stylus-type contact surface profilometry for determining the friction properties of paper. Another objective was to introduce the concept of the mean absolute deviation (MAD) from the average coefficient of friction as a new friction parameter.