Brummer Exterior Wood Filler is ready mixed, waterproof and can be used under most types of decorative finish including polish, lacquer, varnish and paint. It is also impervious to sea-water and can be used for most marine applications as it will not shrink or crack and, just like wood itself, Brummer Exterior Wood Filler can be drilled and sanded. It can also be used on concrete, plaster, fibreglass and stonework. Ideal for window frames, garden furniture, caravans, and many marine applications,