Let's face it, we're natural materials and traditional methods geeks. Materials matter above all else and we've done our homework and testing to find the highest quality and highest performance materials in the US. At the foundation of Earthaus Plasters is limestone, a sedimentary rock made of calcified shells and corals originating from shallow seas from millions of years ago. Explore how limestone is processed into workable plaster and back into limestone, and the amazing characteristics of other natural raw materials that make up our beautiful finishes.
To become usable lime plaster and limewash, limestone is refined using heat and water. Once applied, lime plaster cures back into limestone.
The Lime Cycle: An Elemental Process
Earth: Limestone (Calcium Carbonate CaCO3) is quarried
Fire: Limestone is heated in a kiln to a very high temperature and the carbon dioxide and water vaporize. In this process limestone is transformed into quicklime (Calcium Oxide CaO) and is very alkaline.
Water: Water is added to the quicklime and becomes hydrated lime (Calcium Hydroxide Ca(OH)2). Lime can be hydrated either into a dry powder or a wet putty.
Craft: Hydrated lime is useful as a plaster or mortar by mixing it with aggregates (in our case, pumice) or alone as limewash.
Air: Applied as a veneer plaster or a limewash coating, as hydrated lime dries and cures, it re-carbonates and transforms back into limestone (Calcium Carbonate CaCO3) again.
Pumice is an igneous rock created when magma cools suddenly. The ancient Romans discovered that mixing crushed pumice (pozzolana in Italian) with lime made it cementitious. Cementitious lime is very hard, durable, and not very water-soluble.
Cellulose is plant fiber, the main structural component found in the cell walls of plants. Added to lime plaster, it functions as a binder and increases adhesion and workability.
Olive Oil Soap
Olive Oil Soap is a castile soap that’s chemical-free and does not have any synthetic ingredients or animal fat in it. Soap has been used for thousands of years to seal and protect lime plasters because it has a unique chemical reaction with the high calcium content of lime.
Beeswax is the wax that honeybees secrete and use to mold their honeycombs walls. Made of nearly 300 different compounds, including acids, esters, polyesters, fatty alcohols, and more, beeswax is an incredible yet complex product that’d be hard to replicate by humans. Earthaus Beeswax Protective Sealer is made with beeswax emulsified with water and functions as a liquid sealer for application over Olive Oil Soap Sealer for an extra layer of protection over Plaster Finishes.
Our colors are crafted with nine earthen mineral pigments: black iron oxide, raw umber, red iron oxides, yellow iron oxides, chrome oxide green, ultramarine blue, and titanium white. Mineral pigments give unparalleled depth and beauty to lime plaster finishes.