Deck-O-Seal® 4702032 96 oz Gray Gun Grade Cold Applied Joint Sealant. DECK-O-SEAL GUN GRADE is a two-component, non-sag, non-flowing, polysulfide-based sealing compound. It is a non-staining sealant that cures to a firm, flexible, tear resistant rubber. DECK-O-SEAL GUN GRADE is highly resilient and has excellent recovery characteristics, even after extended periods of compression or elongation. It has outstanding resistance to most chemicals, to all weather conditions, aging and shrinkage.