A traditional wall coating made from lime and water, white unless an earth pigment is added, brushed on in thin coats that have to be renewed.
Conservation bodies describe it by what it does: with harling and lime render it protected masonry from rain, wind and frost, and it lets a wall dry out. Historic Environment Scotland calls it sacrificial, meaning the coat weathers away in place of the wall. Colour came from the few earth pigments cheap enough to add, giving reds from pale pink to deep maroon and yellows as a range of creams.
Limewash is not simply white paint, and whitewashed walls were not chosen mainly for their colour. Where the reasons are documented they are practical: covering rough rubble or soft stone and keeping the building watertight.
In Pembrokeshire a farmhouse was traditionally limewashed red or yellow, its principal outbuildings white, and lesser buildings left as bare stone.
Much stone now on show was once coated, so the bare masonry of a 'stone' village can be a modern preference and not its historic colour.
Historic limewash colour is rarely measured at all, and that is the main thing to know about it. None of the conservation and planning bodies cited here publishes a colour reference for its limewash colours; they describe them in words, such as reds from the palest pink to deep maroon. Suffolk's planning authorities state that evidence for the colours used on the county's buildings before colour photography is limited, with only some evidence for the pink the county is known for. A colour quoted for a traditional limewash is therefore usually a modern product matched to a description, not a record of the historic coat.
A palette for a 'stone village' is drawn from how its buildings look today.
Where limewash and harling have worn away or been stripped, the exposed rubble is a modern look that differs from the buildings' historic appearance. The palette then records a twentieth-century taste for bare masonry.
A settlement's white walls are explained by a single reason, such as keeping cool.
The documented reasons are local and practical: soft limestone and rainwater-collecting roofs in Bermuda, coral rag in Zanzibar, rough rubble in Pembrokeshire. Cooling is a real effect of a light surface but is not the reason these sources give.