CRL Gray Smooth Polyurethane Construction Sealant Cartridge - Caulk

• One-part modified polyurethane construction sealant with primerless adhesion on most common construction surfaces, including KYNAR® coated metals
• AAMA approved for exterior perimeter applications
• VOC compliant — only 9 g/L (low-VOC sealant)
• UV resistant and non-yellowing for exterior exposure

SKU: M64GRY

CRL M64 is a one-part, moisture-curing, gun-grade modified polyurethane sealant engineered for moving joints in building construction. The primerless adhesion simplifies installation on common substrates while providing durable, permanently flexible performance for storefronts, curtain walls, and perimeter joint sealing.

Key applications

• Exterior and interior perimeter joints between framing (door and window) and structure
• Storefront and curtain wall sealing for watertight installations
• Insulating glass toe or heel beads (compatible with insulating glass sealants)
• Concrete, masonry, metal, aluminum, galvanized steel, plastics, vinyl, glass, wood, brass and other common building substrates
• Manufacturing uses: travel trailers, mobile homes, and galvanized HVAC ductwork assembly

Highlights & differentiators

• Exceptional adhesion to fluoropolymer metal coatings — ideal for KYNAR®, Duranar®, and Duranar® Sunstorm™ coated metals (primerless on most substrates)
• Low-VOC formulation (9 g/L) — solvent-free, isocyanate-free and qualifies for LEED Indoor Environmental Quality credit
• Permanently flexible — resists hardening with age and remains flexible at low temperatures
• Fast curing: skins over in ~30 minutes; cures ~1/8" (3 mm) per day
• Paintable after just two hours with water-based paints
• Wide service temperature after full cure: -75°F to 300°F (-59°C to 149°C)

Performance & handling

• Low temperature gunning and application above 0°F (-18°C)
• Tooling time approximately 20–40 minutes depending on temperature and humidity
• UV resistant — will not yellow from sun exposure

Technical data & approvals

Conforms to Federal Specification TT-S-00230C, Type II, Class A and ASTM C920 (Type S, Grade NS, Class 25). Also meets multiple ASTM standards and CAN/CGSB-19.13-M87 (QPL # 81026). AAMA 808.3-92 Exterior Perimeter and AAMA 802.3-92 ductile back bedding compound. USDA