The understated sculptures and video installations in Erin Shirreff’s second solo exhibition at Lisa Cooley dwell on the subtleties of their materials. Drop (no. 1) and Drop (no. 3) look like the remains of eccentric modernist sculptures that have been disassembled, flattened into delicate sheets and hung out to dry. If the paper-thin forms of her steel sculptures belie their true weight, Shirreff’s videos insist on the objecthood of images. For Medardo Rosso, Madame X, 1896, Shirreff re-photographed a reproduction of Rosso’s well-known sculpture under different lighting conditions, emphasizing glares and reflections. The work is not an appropriated “picture,” or a weightless image, but a study of a material thing.