Surface characteristics are understood to mean the topography (geometric structure of the paper's surface) and surface strength of the paper. These determine the visual impression and texture of the paper.

Paper gloss

The gloss of the paper is the visual impression you get when looking at the surface. Paper seems glossier if the most significant portion of the incident light is reflected directly and only a small part is reflected diffusely. In technical measurement terms, gloss is the name for the volume of directional light reflected by a paper surface. Normally the paper surface is illuminated at an angle of less than 75° and the reflected light is measured at the same angle.

The most common ways to measure gloss are with the Hunter and Lehmann measurement methods, however these are not comparable with each other. The fact that both methods are used is due to historical and geographical circumstances. In central Europe, paper gloss is normally measured according to Lehmann's method. Gloss is an important feature for judging the quality of a printed image on the paper surface. A high-gloss print image can be produced on matt or silk-matt paper, achieving greater contrast between images and other
print elements.

Roughness

The roughness characterises the unevenness or topography of the paper's surface.
The greater the profile peaks and troughs the rougher the paper. The measurement for the roughness or smoothness of paper according to Bendtsen or PPS (Parker Print-Surf) is determined by the amount of air that passes between a surface of defined evenness and the surface of the test piece under defined conditions. In the case of uncoated paper types, the roughness is specified according to Bendtsen, while the roughness of coated paper is specified according to PPS.

The higher the surface roughness, the poorer the print quality. Just as there are many different types of landscape, so there are very different paper surfaces. Thus, for example, in the case of uncoated paper, the pores between the individual fibres are relatively large, so that the surface is like a landscape of mountains and valleys.

Dry picking resistance

Dry picking resistance is an important characteristic of coated sheet-fed offset papers for assessing the picking effect in the printing press. It indicates how well the coating binds with itself and with the base paper.

In offset printing, huge tack forces are applied through the film splitting of the ink and the adhesion of the rubber blanket. The effect of this force is to give rise to the risk that individual fibres, fillers or whole coated areas could be torn out.

Measurements are by means of a laboratory printing press. This is used to simulate picking between the paper and ink at different printing speeds. Excessively high
printing speeds (3 m/s) or excessive tack (adhesion or tackiness) in the ink can cause the raw paper to split.