What can I do about powdery and chalky surfaces on external masonry?

Brick and masonry surfaces painted with cement-based paint will eventually corrode and become powdery or chalky. Even unpainted pebbledash or render can become powdery with age. In each case, ensure the surface is sound, clean and dry. Remove all loose material with a stiff brush or paint scraper. If powdery or chalky residues still remain, stabilise the surface with a coat of Weathershield Stabilising Primer. However, don't use a stabilising solution on new or sound bare rendering that has never been painted. A well-thinned first coat of the appropriate Weathershield Masonry Paint is usually all that is required.