CRL M66 Gray Modified Polyurethane Construction Sealant Sausage Pack

• One-part, grainy textured finish with primerless adhesion on most construction surfaces, including KYNAR® coated metals
• AAMA approved
• VOC compliant — only 9 g/L
• UV resistant / non-yellowing

CRL M66 (SKU: M66SGRY) is a one-part, moisture-curing, gun-grade modified polyurethane construction sealant designed for moving joints in storefronts, curtain walls, concrete, masonry, metal, and general perimeter sealing. It typically requires no primer on common substrates and delivers durable, flexible performance in exterior and interior applications.

Basic Uses
CRL M66 Modified Polyurethane Construction Sealant outperforms traditional solvent polyurethanes for sealing moving joints in concrete, masonry, metal, and perimeter applications. Ideal for joints between framing (door and window) and building structure in storefronts and curtain walls, it provides a watertight installation and excellent adhesion to fluoropolymer paint coatings such as KYNAR®, Duranar®, and Duranar® Sunstorm™. Also bonds to standard metal, aluminum, steel, galvanized steel, plastics, vinyl, glass, wood, concrete, brass, and other common substrates.

Compatible with insulating glass sealants when used as a toe or heel bead. Designed for exterior and interior use; service temperature after full cure ranges from -75°F to 300°F (-59°C to 149°C). Paintable with water-based paints after only two hours. The light grainy texture blends with stucco, masonry, and smooth metal joints, concealing tooling marks. Suitable for manufacturing uses such as travel trailers, mobile homes, and galvanized HVAC ductwork assembly.

FEATURES

• Exceptional adhesion to KYNAR® coated metals — ideal for metal storefront and curtain wall sealing
• VOC compliant — only 9 g/L (chemically curing < 3%)
• Eco-friendly: solvent-free, isocyanate-free, qualifies for LEED® EQ credit (indoor environmental air quality)
• Low-temperature application and gunning above 0°F (-18°C)
• Permanently flexible — resists hardening with age, remains flexible at low temperatures
• Fast cure: skins over in ~30 minutes; cures ~1/8" (3 mm) per day
• Tooling time: approximately 20–40 minutes (dependent on temperature/humidity)
• Paintable after 2 hours with water-based paints
• UV resistant — will not yellow with sun exposure

Technical Data
CRL M66 conforms to and passes Federal Specification TT-S-00230C, Type II, Class A, and ASTM C920-98 (Type S, Grade NS, Class 25, Use NT, M, T, A, G, and O). Also conforms to multiple ASTM standards (C510, C639, C661, C679, C717, C719, C793, C