Glass Fibre Filler (Fibre Tough) is a high quality reinforced polyester putty designed for trade use. Glass Fibre Filler is dependable and easy to use, and is formulated to bridge holes up to 50mm in diameter in rusted metal panels in motor vehicles, caravans, trailers, boats and guttering. Glass Fibre Filler is fast-setting, exhibits maximum adhesion to metal with excellent resistance to shrinkage and is waterproof when fully cured. Glass Fibre Filler may be moulded to any shape or contour but it is easy to cheese-grate, file or sand to roughly the finished shape. For holes larger than 50mm in diameter Septone recommend using mender patches of fibreglass mat in conjunction with Glass Fibre Filler. After using Glass Fibre Filler for hole bridging, final shaping of the filled hole should be performed with a standard lightweight body filler, which is easier to sand and shape to the final contour required.