Thank you for your replies. The wall in question surrounds a courtyard, part of which is roofed and part not. It is located to the rear of a house in Pezenas. It is open to the elements but protected by the rear wall and so does not suffer too much from the weather. I think that what I am looking for is a white cement render. Is this something that has to be made up or can it be bought pre-mixed and, if so, is there a word for it. Thanks for your help. Adr