A surface texture that is wrinkled, creased, or ridged.(pr. roo-GAH-sə-tee)Generally unwanted in paintings, rugosity can develop for any of several reasons, although it is much less likely to occur while using good quality artist's materials. Likely causes include: The paint puddled or was applied too thickly. A later coat was applied before an earlier one dried. An upper layer of paint can move as the paint underneath (a primer, perhaps) is drying. The paint was applied while the temperature of the environment was too hot. (Could it be that the paint or the support was too hot? Interesting!) Also see boss, dent, emboss, fluted, fold, kerf, permanence, pleat, and repouss?.