This part of ISO 9117 specifies a test for determining the times taken to reach various stages of drying of organic coatings, using a mechanical straight-line or circular drying-time recorder. The use of a mechanical recorder is valuable in comparing the drying behaviour of coatings of the same generic type, when one coating might form a gel at a faster rate than another or might resist scratching better than another. The test is intended to simulate the conditions which exist when painted articles are stacked upon each other. The drying time of a coating is significant in determining when a freshly painted room, floor or stairway may be put back in use or when a freshly coated article may be handled or packaged. Slow drying might result in dirt pick-up or, on an exterior surface, moisture might cause a non-uniform appearance. The test is used to determine the various stages of drying or curing in the dry-film formation of organic coatings. Mechanical equipment is used for the purpose of comparing types of coating or ingredient changes, or both. To evaluate the stages of drying in a quantitative manner, the use of the recorder under controlled environmental conditions is strongly recommended. This equipment also offers a method of determining the drying characteristics of coatings that cannot be ascertained within the standard 8 h working day. This test is useful in comparing the behaviour, during drying, of coatings of the same generic type. Determination of actual drying times should be conducted following procedures specified, for example, in ISO 9117-1 or ISO 9117-3. 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.