MULCO® GUTTER is an exterior, thermoplastic, one-component sealant. The waterproofing sealant is formulated to be used outdoors for sealing PVC (polyvinyl chloride) or aluminum joints of gutters and drainpipes. Gutter can be applied to damp and wet surfaces in all seasons.‡‡ Gutter sealant must be at least 5°C (40°F).