Tadelakt is a historical means of applying and treating lime plasters to make them waterproof. Originating in Morocco, the plasters are applied in successive thin layers, troweled smooth and then burnished with hard stones using an olive oil soap. The soap and the lime have a chemical reaction that creates the waterproofing. The soap and stone burnishing also creates a beautiful, glassy finish that is amazing to see and touch!
Over five days, instructor Ryan Chivers of Limestrong taught our group of intrepid plasterers a remarkable amount about lime and lime plastering. Here’s a quick look at what we covered in the workshop…
A Bit About Lime
The process of actually mixing the plaster is the same that we’ve experienced with clay and lime cement plasters. One of the best things Ryan taught us was that the need to “slake” lime into a putty is really not necessary with modern, Type S lime. Modern, north american limes are processed in such a way that they are fully hydrated at the manufacturer using heat and pressure. This greatly simplifies the process of working with lime plasters of all types as the weeks or months of slaking in water are eliminated. However, the plasters do want to be mixed at least a few hours before use as the lime does take some time to fully take up the water that’s been added. We mixed a day ahead of ourselves throughout the workshop.
Applying Lime Plaster
Our first plastering was not tadelakt, but a finish lime plaster that was applied directly over painted drywall. The walls were prepared by painting on a mix of white glue and sand, which gave adhesion for the plaster. We then applied two very thin coats of lime. This system was very quick (a 12×15 room took about 1 hour for 2 people to apply, per coat). We’ll post finished pictures of the room once it’s all cured.
Tadelakt is all about timing! You could read about doing tadelakt forever, but it’s all about timing, feel and doing the right thing at the right time. Luckily, Ryan was great at preparing us for what to expect at each stage. By practicing first on our tiles and cob balls, everybody began to understand the stages of tadelakt and how to know when it was time to move on.
We did one tadelakt wall in a “dry” area of the house. To be fully waterproof, the tadelakt must be done just right, so we had one wall that will not be exposed to direct water on which to practice. And it’s a good thing… it really does take a lot of practice (much more than one wall!) to get a feel for the technique.
Tadelakt is beautiful anywhere, but in bathrooms, showers and other wet areas it mixes beauty and functionality like no other natural material.
The timing for tadelakt gets more complex the more surface area there is to cover. In this bathroom, we had several different substrates under the tadelakt which all affected the timing, and we had many people applying, troweling, stoning and soaping. The result, however, is a wonderful, rich, shiny plaster!
In the end, the crew did an amazing job. We’ve all been promised a nice hot shower in the finished bathroom to appreciate our work!
We’ll post photos of the finished bathroom when it’s ready. The tadelakt takes 28 days to fully cure…
Our thanks to Ryan for teaching a terrific workshop and to all the participants for so much fun, hard work and learning together!