Apparel Interfacing Apparel Interfacings provide structure and support to areas of fashion fabric where strengthening is needed, for instance in shirt collars and cuffs, waistbands, plackets and lapels. Interfacing is also used to maintain shape in delicate fabrics. Pellon® interfacings can be found in different weights and styles for all your apparel needs. Pellon® interfacings are available in both fusible and sew-in options.