Polar Leak Seal Paint is ideal for use on flat and pitched roofs, weathered asphalt, bitumen surfaces, felt shed roofs, gutters, drainpipes, concrete, brick, GRP, fibreglass roofs, felt roofs and metal roofing surfaces. Instant Waterproof Roof Sealant. Ideal for Leaks, Cracks & Roof Repair - Concrete, Brick, Metal, Drainpipes & Gutters. Easy to Apply.