How it began
Tadelakt is a waterproof plaster surface of Moroccan architecture. The sources consulted do not give a date for its beginning. A supplier's history states that it was first used by the Berbers to waterproof earthen cisterns for storing drinking water, and that it is made from traditional materials found on the Marrakech plateau. The name, meaning to rub in, is an Amazigh form of the Arabic word tadlik, to rub or massage.
How it works
Lime plaster powder is mixed with water for 12 to 15 hours before pigment is added. The plaster is applied in one thick coat with a wooden float. Before it sets, a flat, smooth, hard stone is used to compress it, and it is then polished. Finally an olive oil soap solution is rubbed in. The soap reacts with the lime to form calcium soaps, which are insoluble in water and fairly hard, so the surface repels water.
What changed first
Because it is applied as a paste, tadelakt can follow curves and has no joints through which water could pass. It became the traditional coating of hammams and of the bathrooms of palaces and riad houses in Morocco, and was used for baths, sinks, water vessels, walls, ceilings, roofs and floors. Deep red is the traditional color.
Where it stands today
Tadelakt is labor-intensive to install but durable, and it needs to be resealed with soap solution from time to time. The restoration of riads in Morocco has brought the technique back into wide use, and it is now sold abroad for interior walls, baths and wet rooms. Conservation scientists have studied old tadelakt-lined steam baths in Moroccan kasbahs as examples of water-repellent lime plaster.
