06 Oct Outdoor Polished Plaster solutions
Traditional Venetian polished plaster, also known as Marmorino, Spatulato, Marble plaster, Italian plaster or Stucco Veneziano, is not suitable for outdoor application. Although when applied indoors it is sealed to make it waterproof and water-repellent, the sealing process is not robust enough for outdoor use.
Instead, a different type of plaster is often used outdoors. This is called Tadelakt. Tadelakt originates from Morocco. It was originally created to waterproof cisterns. It has been used for centuries to waterproof various outdoor structures because it is impermeable and highly resistant to rapid changes in temperature.
Tadelakt is composed of a lime putty, marble powder and quartz sands of various different grains. The plaster is rammed (compacted), smoothed, polished, and treated with a special soap to make it waterproof and water-repellent.
Traditionally, Tadelakt uses a very specific type of lime called hydraulic lime which is produced by burning limestone with olive tree and palm wood. The lime is then mixed with aggregate (stone dust, sand) and water. The natural colour is light, so natural pigments can be added to darken or colour the mixture.
This plaster is extremely durable and beautiful. It is widely used around the world for exterior walls, water vessels and floors. It is suitable for flat or curved surfaces. It does have a downside though and that is the labour time. It takes a long time to apply because it has a paste consistency. Thus, a perfect finish takes longer to achieve.
Although traditional Venetian plaster is not suitable for outdoor use, there are modern Venetian-style plasters out there that are. These have an acrylic polymer content, allowing for a stucco or one coat stucco to be applied outdoors. The acrylic polymer bonds with the lime putty, which gives it suitability for outdoor use.
Because these plasters contain natural stone dust, when they are polished they mimic traditional Venetian polished plaster well. This makes them a good solution for replicating the look of Stucco Veneziano outdoors. There are a few manufacturers of such products. A Good example is EuroPlast from Stuc-o-flex.
Another good product is Armourcoat PPX. This incorporates acrylic polymers into its mix too, creating a water-resistant and vapour permeable layer that adheres to exterior walls very well. When polished, it has its own unique appearance which is not dissimilar to Stucco Veneziano but is slightly coarser in character.
Polished plaster for your outdoor project
If you want to use polished plaster outdoors or in very wet areas, Tadelakt is a very good choice because it is proven in Moroccan culture. However, acrylic plaster is a more affordable option. It’s easier and quicker to apply than Tadelakt, and some people prefer the appearance of an acrylic finish.
Feel free to contact us to find out more about any of these systems. We are plastering experts who can recommend products for any use case. Call us on 0772 548 866 or send us a message to find out more. Thank you.