Acetate: Acetate provides excellent drapability and softness, and is moth resistant. Acetate is dry-clean only. b) Polyester: Polyester is strong; moth resistant; resistant to stretching, most chemicals, and abrasion; is crisp and resilient when wet or dry; retains heat-set pleats and creases; is more wrinkle resistant than Acetate; and is easily washed in ordinary washers and dryers. In addition, Polyester colors tend to be more stable over time than Acetate, though can fade from long exposure to the sun. Polyester is the standard fabric for Keeper® orders. Academic believes that polyester is a slightly better fabric than acetate, and is therefore moving over to polyester-only Keeper graduation robes. If you would prefer acetate robes, please call and request that we check our inventory to see if we have enough acetate remaining in stock to supply your order.