Most of the musem’s archive rooms look like this: Items of clothing in Tyvek bags, with periods, styles, or designers labeled at the front of each rolling shelf like in a library. “The more precious pieces are the dresses with trains, which are too long to keep on a hanger, and have to be stored in boxes,” says Mertens. “Pieces that are in especially bad condition have to be kept in acid-free paper boxes.”