EVERBUILD PURIMACHOS BLACK HIGH HEAT RESISTANT SILICONE SEALANT 300ml FAST CURE. Heat Resistant Silicone is a high temperature resistant, fast cure, silicone, heat stable up to 300 degrees C, which is a permanent flexibility- high modulus sealant. It is ideal for joints and assemblies in ducting, metal chimneys, industrial/domestic ovens and heating appliances. Excellent adhesion to most non-porous surfaces.