Pellon SF785 Woven Sew-In Interfacing 20″ x 10 yards Bolt. Color: White. Fiber Content: 55% Cotton / 45% Polyester. Application Method: Sew-In. Woven Sew-In Heavy Weight is an all purpose, woven sew-in interfacing for medium to heavy-weight fabrics. It adds body and crispness to a variety of projects including shirts, jackets, and ties or can even function as a stand alone fabric. It is great for use with fabric such as oxford cloth, chambray, poplin, and calico.