Isophthalic Gelcoat (Black, Marine Grade)

This black isophthalic gelcoat combines the hydrolytic resistance and weathering durability of an isophthalic resin base with deep carbon black pigmentation for demanding marine and outdoor composite applications. It is formulated for use on boat hulls, watercraft exteriors, and other FRP components exposed to continuous immersion or harsh UV environments where an orthophthalic black gelcoat would be inadequate. The iso resin backbone reduces osmotic blistering risk under prolonged water contact, a critical performance criterion for below-waterline hull areas. Pre-accelerated with cobalt for MEKP catalysis at 1–2% by weight. The thixotropic consistency allows spray application at 0.4–0.6 mm wet film thickness without draining or sagging on curved surfaces. Gel time at 20°C is 25–45 minutes with 1.5% MEKP. Cured Barcol hardness typically reaches 42–50. The product is compatible with isophthalic laminate systems and standard polyester structural composites within the tack window. Post-cure, the surface exhibits excellent adhesion to antifouling and topcoat paints. Supplied in containers from 5 kg to 200 kg.