Tracing its American roots to Austrian-trained upholsterer Samuel Langer, Jonas handcrafts custom upholstered furniture and curtains in its Manhattan workroom for the design trade. Now carried on by Langer’s descendants through Steven Jonas and Charles Berlin, the atelier preserves 19th-century methods, including hand-tied springs and hand-stitched horsehair, in pieces made for lasting use. Its work has furnished the White House, Blair House, and the vice president’s residence for more than 50 years.