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Introduction to Clay Plasters: Beautiful and Sustainable

Imagine the walls of your home giving you a warm, gentle hug every time you are in a room. That’s the way most homeowners describe the effect of clay plasters as a wall finish. Clay plasters are also among the very greenest finishing materials available, making them an attractive option for remodeling an existing room or for new construction.

The use of decorative clay plasters is as old a practice as home building itself. The insides of caves, grass huts and early stone buildings around the world were finished with coloured clay plasters. Largely ignored in North America for the past couple of centuries, the use of clay plasters is enjoying a remarkable resurgence as homeowners seek natural, healthy and affordable ways to enrich their homes.

At Endeavour Centre, we love Natural Plasters. We organize workshops, full programs and develop new ways to teach Natural Plasters for people far from our school.

The basic ingredients in a clay finish plaster are no different today than they were thousands of years ago: clay, sand, pigment and a glue-like binder (often based on cooked flour!). What has changed is the method of application. In the past, many clay plasters were applied by hand to rough, uneven walls. Now they are applied with trowels onto straight, flat wall surfaces. But the link to the past is obvious when you experience a modern clay plaster, as the richness and depth of color and the unique interaction with light and sound are unparalleled by any modern materials.

For those concerned with indoor air quality, a clay plaster is a great choice. They are completely non-toxic and do not off-gas in the wet or dry state. They involve no petroleum products or other chemicals in their manufacture or application, and have been shown in German research to have some effectiveness at absorbing and transforming pollutants in the household air. The same research shows them to have excellent moisture-handling properties, helping to regulate humidity in the home.

Clay plasters can be applied directly over most existing wall surfaces and finishes, including latex and oil paints, drywall and paneling. On painted surfaces, a mixture of natural glue and sand is rolled onto the wall to provide the plaster with “tooth,” a rough surface that allows the plaster to grip the wall. The plaster can be recoated in the future, or can be painted over with conventional or clay-based paints.

The application of clay plasters takes some practice, but it is well within the ability of most homeowners to apply. Some practice on a spare sheet of drywall will help you to hone a technique, and with this new learning tool we are crowd funding, let us help you tackle your next Natural Plaster project. The plasters can be applied with an endless variation of appearances, from perfectly smooth to roughly troweled or textured finishes. The plasters can be burnished so they shine, or left with matt surfaces. The possibilities are almost endless. A wide range of natural pigments allows a vast range of colors to be achieved, and the colors tend to be warmer and “friendlier” than synthetics.

There are some manufactured clay plasters available on the market, and these products have been largely responsible for the surge of popularity for this type of finish. It is also straightforward to make your own clay finish plasters from locally available ingredients with the help of some research and instruction on creating mixes. Buyers should be wary of products marketed as clay plasters that feature some amount of clay in a petroleum-based paint.

Clay plastered walls invite amazed reactions and a desire to touch the wall from those experiencing them for the first time. Unique, beautiful, healthy and affordable; there is nothing that quite compares to a clay plastered wall.

Take a look at our Kickstarter campaign to learn more about clay and other Natural Plasters. Let the mud be spread!

2 Comments

  1. Is it possible to use this on exterior walls? I would expect some modification to the mixture. Would it be possible to use it in tropical countries, like Costa Rica, with all the rain and the heat we have?

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