For more than three decades, Thomas Hartmann has explored the materiality of oil paint and repeatedly shown how it can attenuate tensions between interior and exterior, massive and minute, visible and legible. Like many postwar German painters—from Anselm Kiefer to David Schnell—Hartmann pursues this investigation at the border of figuration and abstraction. Crystallizing his unique achievement, the seven large oils exhibited recently in Vienna concern the ubiquity and increasing homogeneity of storage in contemporary life. The canvases suggest shelves, hard drives, folders, books,

Art lovers expecting the unexpected were amply rewarded by Roman Ondák’s recent exhibition “Erased Wing Mirror.” The Slovakian artist is a master illusionist; he famously made an entire Venice Biennale pavilion vanish into thin air, and once organized a fake queue to make it seem as if a vast public were waiting to view his work. This time he unsettled visitors with a nimble sideways move that took him beyond the bounds of such immaterial artistic gestures.

Mailbox, 2013, a large-format oil painting on the gallery’s main wall, depicts a radiant, lushly green landscape: mountains, a river, and a