Mulco Supra Expert Supra Expert is a super-durable, thermoplastic architectural, one-component sealing compound that dries by solvent evaporation. FEATURES AND BENEFITS Industrial. First-quality thermoplastic rubber-based sealant. For windows and siding. Instant resistance to rain. Super-flexible, super-adherent and super-durable. Adheres to almost any surface. Can stretch up to 1400% without breaking. Bubble-free. AVAILABLE COLORS Back to Mulco