To get the best results with Dulux colour mixing Weathershield Smooth masonry paint, make sure that the surfaces to be painted are sound, clean and dry (new surfaces particularly must be fully dry)Remove any loose or flaking paint. Areas affected by mould, lichen, algae or moss should be treated with a suitable fungicidal wash. Any surface defects should be filled with the appropriate Polycell Polyfilla product. If the surface is still powdery after thorough preparation, seal it with a coat of Weathershield Stabilising Primer, but do not seal sound, new or bare surfaces.