The perfect base primer for use on porous or chalky, interior & exterior masonry, rendered or plastered surfaces. Farrow and Ball Masonry & Plaster Stabilising Primer is for use on interior walls and concrete floors and exterior walls, to seal and stabilise porous, chalky and unsound (crumbly) surfaces. This stabilising primer is not suitable for use on fresh surfaces. This stabilising primer is available in white only and dries clear.