This standard specifies a method of determining Bekk smoothness. It can be used for a wide range of papers and boards and is especially recommended for smooth surfaces. For very smooth products, the duration of measurement can increase considerably. The method should not be used when testing: a) specimens with a thickness as in DIN EN ISO 534 greater than 0,6 mm; b) porous paper and board, since here the volume of air flowing through the specimen can falsify the result; c) very rough paper and board. Bekk smoothness depends on the form, total volume and distribution of pores created between the paper surface and the ideal plane under the specified contact conditions. The higher the Bekk smoothness number, the greater the smoothness. The porosity of the tested product is also included in the measurement. This document has been prepared by Working Committee NA 074-02-03 AA "Physikalisch-technische Prüfverfahren für Papier, Pappe und Faserstoff" ("Physical-technological test methods for paper and board") at DIN Standards Committee Paper, board and pulps (NPa).