Natural Clay Plastering
This information reflects our best understanding of product composition in 2023.
Natural clay plasters are supplied as powder that is mixed with water on site. They are formulated using natural clays, aggregates, fibers, and may contain additional additives. They are generally specified for interior use and commonly applied...
Natural clay plasters are supplied as powder that is mixed with water on site. They are formulated using natural clays, aggregates, fibers, and may contain additional additives. They are generally specified for interior use and commonly applied over drywall, although they can be applied over most substrates excluding composite wood. While some products may be applied in one coat, generally a base coat and a finish coat are specified. Products can contain a mixture of clays that impart different properties to the plaster including ball clays, fire clays, and kaolins. Aggregates consist of silt and sand, and often also include crushed marble, calcium carbonate or crushed shells. Straw may also be added to products for additional texture and to prevent crack formation.
This Common Product describes a natural clay plaster that may be used as either a base coat or a finish coat. While natural clay plasters are mostly composed of minerals, they may contain additional additives. These include fungicides like borax to prevent the growth of mold and mildew, and acrylic polymers to increase durability. Disclosure documents indicate that additional content may be present, but typically withhold the identity of additives as proprietary information.
A number of accessory products are recommended or required when applying natural clay plasters. These include primers, sealers, pigments, and additional additives mixed on site. These products will add additional hazards not considered by this Common Product.