limewashing

Limewashing is a traditional method of coating interior or exterior walls using a lime-based wash. The material is typically prepared from lime putty or hydrated lime mixed with water, and sometimes colored with natural pigments to produce a white, cream, or earth-toned finish. The film is breathable and porous, allowing moisture to diffuse through the coating while shedding rain at the surface. It does not form a hard, water-tight film, which helps prevent trapping moisture in masonry.

Historically, limewash was widely used on stone, brick, and plaster walls in Europe from antiquity through the medieval and early modern periods. Today it is used in restoration to match historic appearances and in new construction that follows traditional lime-based techniques.

Application generally involves cleaning or dampening the wall, applying one or more thin coats of limewash with a brush. A rough undercoat is often followed by one or two finish coats. The coating cures by carbonation, reacting with carbon dioxide in the air, rather than by drying. Drying is slower indoors or in cold weather.

Durability and maintenance: exterior limewash gradually wears away and chalks, especially in exposed areas; a fresh coat is typically reapplied every 5–15 years depending on climate, substrate, and traffic. Recoating should be done on sound, prepared surfaces to avoid flaking. Limewash is compatible with lime plaster and masonry but is not a substitute for modern damp-proofing in all situations.

Safety: lime is caustic to skin and eyes; protective clothing and eye protection are advised when mixing or applying.