GreatSeal LF-500 is a high performance sealant designed for use as a liquid flashing. LF-500 provides a long lasting weather tight seal to a variety of building substrates. LF-500 is a single component unique polymer that will bond to damp surfaces and has excellent weathering properties for a long lasting seal. LF-500 Liquid Flashing can be applied with a brush or trowel when using it as a flashing/repair product.