Nicola Martini’s exhibition “Sippe,” whose title is a German word meaning “tribe,” “clan,” or “kin,” brought to mind the facades of houses in centuries-old Italian villages, their outer walls plastered with water-based paints that become bleached by the sun or washed away by rainstorms. The evanescent colors of these surfaces look as if they could fade away before your eyes. But in this show, the colors were on inner rather than outer walls. And the hues were dark, even somber, the walls in question having been treated with bitumen of Judea, a photosensitive asphalt that grows lighter over time,