Mahdessian and Cameron Silver, co-owner and founder of Decades in Los Angeles, both counsel taking beloved pieces to a good dry cleaner first. “Many ‘40s dresses are rayon, which is not smart to hand wash,” says Silver. More recent pieces in sturdier fabrics can be washed gently. Franco mixes a bath of Palmolive and a pinch of OxiClean. “I’ve soaked pieces for up to two weeks,” she says. Silver’s preferred suds are Citrus Magic Fine Fabric Wash.