DIN EN ISO 9117-5:2012-11

This part of ISO 9117 specifies a method for determining whether coatings, including those produced using multi-coat systems, have reached various stages of drying. Furthermore, it allows the drying speed to be assessed. In the case of plastic coatings, it is only possible to determine to a limited extent whether drying stages 4 to 7 have been reached, as the elasto-plastic behaviour of these coatings cannot be evaluated on the basis of a temporary visible change in the coating surface. The processes which take place during film formation in the case of physical drying or oxidative/reaction-controlled drying are so different that a clear distinction between grades is not possible. Therefore, when testing using this part of ISO 9117, it is possible that, within the range covered by drying stages 4 to 7, a higher drying stage might be reached before a lower drying stage. For this reason, a difference of one drying stage within this range does not necessarily mean a specific difference in drying speed. Elasto-plastic coatings might never reach drying stages 5 to 7. If the surface is tacky, it is also possible that the high drying stages of this standard will not be reached, although the surface appears completely dry. Generally, the visible changes involved in drying stages 4 and 6 can be evaluated more exactly on glossy surfaces than on matt or structured surfaces. The test described in this part of ISO 9117 should therefore be seen as a technological tool with relatively limited usefulness. The test (if used in connection with other test procedures) should, however, ensure that the interested parties can agree on a measure for the performance characteristic referred to as "drying speed". The committee responsible for this standard is NA 002-00-07 AA "Allgemeine Prüfverfahren für Beschichtungsstoffe und Beschichtungen" ("General test methods for coating materials and coatings") at DIN.