Tadelakt is a type of lime-based plaster — and the specific technique used to apply it — that was originally made and used specifically in Morocco. It is applied to either inner or outer walls in the same manner as other types of plaster, but tadelakt is polished with smooth stone, and a special soap is applied before it dries. The result is a satin, sometimes shiny, waterproof finish.
Lime from the Marrakech region of Morocco was used to make traditional tadelakt. The main base for this plaster is lime. Sometimes fine sand made from either marble or limestone will be added, and the mixture will be saturated with water. Since plain tadelakt is light in color, pigmentation or tint may be added to give the plaster some color.
After the plaster is thoroughly combined, it should sit for a short period of time before it is worked with. A metal trowel is typically used to apply the plaster. Although a Swiss trowel is the traditional tool for this job, any large metal trowel is fine.
The first coat should dry almost completely before putting the second coat of plaster is applied over it. This generally takes around a day on average. Any trowel marks should be smoothed out, since this will affect the appearance of the finished wall. If desired, a very thin and final coat of tadelakt can then be applied before polishing.
To achieve the satin smooth finish that tadelakt is known for, the plaster must be polished before the last coat dries completely. The traditional method of polishing this plaster involved rubbing it with a smooth rounded river stone, known as a galet. Although some individuals still use this method, many use a plastic or metal trowel, or a ceramic buffing wheel to burnish the plaster.
The final step when using this technique is applying a special soap, often referred to as black soap. This dark soap is made from olive resin. The water-resistant qualities of this type of plaster is attributed to the soap coating. Tadelakt plaster is so water resistant that it is often used in the public steam baths that can be found all over Morocco.
Before the modern age of indoor plumbing, these public baths were common and could be found on just about every street corner. Today, although their numbers have shrunk, travelers can still find these public baths throughout Morocco. Visitors can either wash themselves, or, for an extra fee, have a bath attendant wash them.