Rustins Acrylic Wood Filler is a fast-drying, ready to use flexible filler that is easy to sand, stain and paint. Suitable for interior and exterior use. Once dry, the filler can be painted, stained or varnished. Try a small inconspicuous area first as the filler may stain on the area filled. Preparation: the surface must be clean, dry and free from all traces of oil, grease and dust. Application: using a suitable filling knife, work the filler into the wood, allowing up to 2 hours to dry between layers. Clean tools in water.