Making Lime Wash — The Oldest and Simplest Wall Paint in the World

Lime wash is perhaps the oldest paint in human history — a simple mixture of slaked lime (calcium hydroxide) and water that has been used to coat walls, buildings, and fences for at least 8,000 years. From Neolithic whitewashed villages in Anatolia to Greek island houses blazing white in the Mediterranean sun, from English country cottages to colonial American barns, lime wash has been the universal wall coating across most of human civilisation. It is cheap, antiseptic, fireproof, breathable, and beautiful.

The chemistry is elegant. Slaked lime (Ca(OH)₂) is mixed with water to a thin cream. When brushed onto a wall, the water evaporates and the calcium hydroxide absorbs carbon dioxide from the air, slowly converting back to calcium carbonate (CaCO₃) — the same mineral as limestone and chalk. This carbonation process takes days to weeks, during which the coating gradually hardens to a durable, crystalline, matte white surface. Each coat is thin and slightly translucent, so multiple coats build up a depth and luminosity that modern emulsion paints cannot match.

Lime wash is also one of the most environmentally friendly paints: the raw material is abundant limestone, the only solvent is water, and the finished coating absorbs CO₂ as it cures. It is naturally antiseptic (the high alkalinity kills bacteria and mould), fire-resistant, and fully breathable — allowing moisture to pass through without trapping damp in walls. Adding earth pigments, iron oxide, or other mineral colours produces a range of beautiful, historically accurate tinted finishes.