Clay Paint & Alise
Finishes: MATERIALS ENCYcLOPEDIA
Applications for this system
Interior walls and ceilings
Not suitable for use on:
– Exterior surfaces
– Metal or plastic
Aggregate (including sand, silica, mica, calcium carbonate)
Binder (including flour paste and casein)
Fibers (if required)
Ratings Chart for Clay paint and alise
The ratings chart shows comparative performance in each criteria category. Click on the tabs below for detailed analysis of each criteria.
- HOW THE SYSTEM WORKS
- ENVIRONMENTAL IMPACTS
- MATERIAL COSTS
- LABOUR INPUT
- SKILL LEVEL REQUIRED
- SOURCING & AVAILABILITY
- INDOOR AIR QUALITY
- FUTURE DEVELOPMENT
Clay paint and alise System
Clay paints are as old as human civilization, as they can be made with materials that occur naturally in most regions. Complementary mineral ingredients have been combined in ways that have lasted tens of thousands of years in the form of cave paintings.
Ingredients can be proportioned and mixed by the homeowner/applicator, or pre-manufactured mixtures can be purchased and mixed with water. Small variations in the mix can have noticeable impacts on the resulting finish, allowing for a wide range of aesthetic possibilities.
Clay paint and alise do not undergo a chemical change when mixed and applied to the wall. If a binder is used, it is typically a water-soluble binder that does not change the chemistry of the paint. The mixture is applied by brush, roller, sponge and/or trowel, depending on the consistency and the desired appearance of the finish. Once applied, the mixture dries and hardens, but is susceptible to damage if wetted.
Clay paint and alise allow a wide range of finishes. Variation in the type, size and quantity of aggregate produce finishes from grainy, heavily textured surfaces to polished, glass-like ones; the finer the aggregate, the smoother the texture. Qualities of the aggregate can become part of the finish, with colored or sparkling sands able to show through the surface. Application techniques such as rubbing, sponging and trowel burnishing will lend the finish different appearances.
Environmental Impact Rating
Harvesting — Negligible to Moderate
Clay, aggregate and other ingredients can be obtained from local soils and sources, making these paints a potentially no-impact finish. If clay, aggregate and other ingredients are purchased commercially, they will have been dug or quarried, with impacts that may include habitat destruction and ground and surface water disruption or contamination.
Manufacturing — Negligible to Low
Commercial ingredients will have been minimally processed. None of the common materials in clay paint require heat input or chemical processes.
Transportation — Negligible to High
Clay and aggregate are heavy materials, and may need to travel long distances.
Installation — Negligible
Compostable — All ingredients.
Recyclable — Containers for ingredients
Material costs: Low
Labour Input: low to High
The wide variety of preparations and application techniques make for widely varying amounts of labor input. At the simplest, the ingredients can be mixed together with water and immediately applied with a brush or roller, comparable to commercial paint. Other mixes and techniques can take substantially longer, involving multiple steps, coats and burnishing.
Clay, sand and pigment are all high in silica dust. Breathing protection should be worn when working with dry ingredients.
Skill level required for homeowners
Preparation of substrate — Easy
On porous surfaces, no preparation may be needed. In some cases, a base of natural glue and aggregate may be desirable.
Application of finish — Easy to Moderate
A simple clay paint can be applied with the same skill level and technique required to apply conventional paint. More elaborate applications require practice and/or a willingness to experiment.
Sourcing & availability: Easy to Difficult
Feasible clay paint can be made from site- or locally-harvested materials. Bagged clay can be obtained from pottery supply outlets. Different types and grades of aggregate and pigment can be found at pottery supply outlets and masonry supply stores. Pigments can be obtained from artist supply shops.
Durability: low to moderate
Clay paints are stable and UV resistant, and can last for hundreds of years. They are prone to softening and erosion in very humid conditions or when exposed to moderate quantities of liquid water.
Polished, burnished surfaces will wear better than rough, porous ones where the paint will be exposed to a lot of contact.
Indoor air quality: high
Clay paints should not have a negative impact on IAQ. Some testing shows that clay paint may have properties that helps to improve indoor air.
Some clays, pigments and aggregates can be contaminated with radon and other radioactive elements, heavy metals and other earth-bound elements. Know the source of all ingredients and research to ensure they are clean.
Resources for further research
Weismann, Adam, and Katy Bryce. Using Natural Finishes: Lime- and Earth-Based Plasters, Renders and Paints: A Step-by-Step Guide. Totnes, UK: Green, 2008. Print.
Edwards, Lynn, and Julia Lawless. The Natural Paint Book: A Complete Guide to Natural Paints, Recipes, and Finishes. Emmaus, PA: Rodale, 2002. Print.
Crews, Carole. Clay Culture: Plasters, Paints and Preservation. Taos, NM: Gourmet Adobe, 2009. Print.
A number of commercially made clay paints have come to market in the past decade, and these formulations are consistent, durable and easy to apply. Improvements in natural chemistry may help the number of products and their effectiveness to continue to improve.
Consumer demand for nontoxic finishes may help clay paints achieve a larger share of the market.
Clay paints create custom finishes, and for owners looking to make a uniquely beautiful home, they offer many possibilities that may make them more popular.
Tips for a successful clay paint/alise finish
1. The range of potential mixtures for making a successful clay paint or alise is extremely wide. This allows for many possible finishes, but also opens the door to mixes that are less than ideal. If mixing your own clay paint, experimentation will lead to feasible recipes and application techniques.
2. While clay paints can be durable and very colorfast, they are not appropriate in wet areas where they can soften and erode.
3. Finish techniques that result in shinier, denser surfaces will be more durable in areas of high wear.
4. Clay paints require a porous substrate, and cannot be successfully applied over glossy, non-porous surfaces.
5. Clay paints invite a sense of play and adventurousness. While it is possible to mix and apply them in a manner that gives very even, consistent results akin to more conventional paints, the beauty of the material is in its variation, whether subtle or intentional.