Ecologically clean clay plaster for the walls of your home

A natural and environmentally beneficial way to finish the walls in your house is with clay plaster. Because it is composed of only three basic materials—clay, sand, and water—it is an excellent option for anyone trying to establish a healthy indoor atmosphere. Compared to conventional wall finishes, clay plaster is safe and environmentally friendly because it doesn’t contain any synthetic materials or dangerous chemicals.

Since ancient times, this particular kind of plaster has been in use because of its great capacity to control interior humidity and preserve a cozy environment. It naturally takes in moisture, releases it, and helps keep mold away while enhancing air quality. Additionally, any space is given a distinct, rustic charm by its earthy tones and textures.

In addition to being good for the environment and your health, applying clay plaster to your walls gives your house a cozy, unique feel. This adaptable material can be shaped and colored to fit your style, whether you’re going for a modern or traditional look. Clay plaster is an excellent material for creating a warm and sustainable living space because it is eco-friendly, long-lasting, and beautiful.

Advantages	Details
Eco-Friendly	Clay plaster is made from natural materials, making it a healthy choice for your home.
Breathable	Clay allows walls to breathe, reducing moisture and preventing mold growth.
Regulates Temperature	It helps maintain a stable indoor climate by absorbing and releasing heat.
Aesthetic Appeal	Clay plaster gives walls a natural, earthy look that can add warmth to any room.
Non-Toxic	Contains no harmful chemicals, making it safe for families and pets.

Types of clay-based plasters

Clays can be classified as either monomineral or polymineral based on their origin. Monomineral clays are formed when one type of mineral breaks down, such as feldspar, and polymineral clays contain impurities of other minerals in addition to kaolin. Impure colors are influenced by impurities.

• white (kaolin);
• yellow;
• blue;
• gray;
• red;
• black.

The composition is strengthened by adding fillers of various origins to increase the strength of the clay plaster coating. These fillers include:

• sawdust;
• pine needles;
• chopped straw;
• flooring, artificial granules, fibers, such as polystyrene foam, fiber.

Plaster compositions vary depending on the type of filler used.

• mixture with sand;
• solution with sawdust;
• combined mixtures – with sawdust and sand.

Sorted by combined binder type:

• clay-lime (1:1:4);
• cement-clay compositions;
• gypsum-clay mixtures;
• clay-acrylic (with starting acrylic putty – author"s).

With a thermal conductivity of 29 W/m*°C, the clay-sawdust coating comes in second place in terms of thermal conductivity, behind the gypsum-perlite composition. Clay has a thermal conductivity of 69 W/m*°C, which is nearly 1.5 times less than that of a cement-sand mixture.

Its density of 1700 kg/m3 is comparable to that of brick.

With its higher vapor permeability than log walls, it works great for plastering wooden houses. Clay has a coefficient of vapor permeability between 0.11 and 0.15 mg/(m*hour*Pa).

The material’s 98% moisture capacity can be an asset or a liability depending on the situation. For instance, it works well when the coating keeps the room’s humidity at a specific level. However, when there is a lot of water present, the coating swells and becomes weaker.

Shrinkage results from swelling during the drying process. The coating doesn’t break down when shrinkage happens gradually. The coating could crack if it dries too quickly.

The amount of clay plaster needed for a 10 mm layer is 15 kg per square meter of surface area.

Advantages and disadvantages of clay compositions

The benefits of clay compositions, which include the following, account for their popularity:

• availability, low cost of the original components;
• environmental friendliness (applicable in children"s institutions);
• repairability (repair is not difficult);
• layer thickness depends on the filler;
• saves heat well (low thermal conductivity of compositions with sawdust, straw, pine needles – the wall is warm even to the touch);
• natural humidity regulator inside the house;
• virtually waste-free (leftovers are stored, used after soaking);
• does not deteriorate;
• long service life;
• easy to lay, you can fill holes, create a texture of any configuration;
• suitable for covering wooden surfaces.

• gets soaked in high humidity, prolonged moisture;
• dries for a long time (up to 2 months);
• the minimum possible layer is 1 cm (otherwise it will peel off, cracking).

What kind of clay is suitable for plastering

Consider the clay’s fat content, plasticity, and level of contamination from large or foreign inclusions when assembling the ingredients of a clay solution for wall plastering. Clay plaster does not contain lean clay.

Making a plaster solution out of clay is feasible:

• light, with plasticity up to 0.27;
• heavy – plasticity above 0.27,

The latter are seldom utilized, though, as temperature fluctuations cause heavy material to crack over time.

In other words, there are circumstances where the deposit "radiates." Plastering should not be done on materials with this level of radioactivity.

Fat content and its definition

The mineral’s granulometric composition varies greatly. Natural materials can be either lean (with lots of sand particles) or fat (with lots of clay and silt particles).

Experimental methods are used to determine the proportions of the composition and the fat content of the clay used to make plaster.

Test batches are combined individually (using volumetric ratios of clay to sand) in order to determine the ideal composition of clay for plastering:

• 1:2;
• 1:3 (most commonly used proportion);
• 1:4;
• 1:5.

1. A 3-4 cm ball is rolled from each batch, then dropped from a height of ~1 meter onto a hard surface. A ball made from a fat composition is strongly flattened (cracks will form when drying), from a lean one – falls apart (the strength of the plaster coating will be low). A composition from which the ball is not greatly damaged and does not crumble when dropped is suitable for plastering.
2. The second way to determine the fat content of a solution is to flatten such a ball to a height half the original. Ideally, shallow cracks should appear along the edges of the cake. If the solution is fat, then the edges remain intact, lean – deep cracks form.
3. From each batch, roll out flagella with a diameter of 15 mm, 20 cm long. Wrap the tourniquet around the handle of a shovel (or other object with a diameter of 5 cm). If there are no cracks or there are few of them, and they are small, then the composition is suitable.
4. Scoop a test batch of the solution onto a trowel moistened with water. Then turn the trowel so that the mixture creeps off it. The trace left on the tool is used to judge the fat content of the solution. Dry will not leave a trace, greasy will leave a lot of sticking, normal – narrow small stripes.

Sand is added to solutions that are fatty, and less sand is added to solutions that are lean.

Obtaining fine clay

There are five degrees of plasticity in clay material, ranging from extremely plastic to non-plastic. This metric is dependent upon:

• dispersity of the material (the smaller the constituent fractions, the more plastic),
• mineralogical composition.

The "old-fashioned" method is used by artists because the elutriation method they use for construction is impractical. After being excavated, the clay material is spread out in 1 m high shafts, moistened, and left in the open area to spend the winter. The ice turns into pliable, loose rock. This kind of material works well for coating stoves and decorative finishing.

An eco-friendly and natural way to finish your walls is with clay plaster, which is a healthy substitute for materials that contain chemicals. It is safe for your home and the environment because it is made of basic, non-toxic materials like sand, clay, and natural fibers. In addition to improving air quality and regulating indoor humidity, clay plaster gives your room a cozy, earthy look. It’s also sustainable and biodegradable, which makes it a fantastic option for people who want to lessen their environmental impact while still designing a warm and inviting home.

Instructions for applying clay plaster

The primary procedures in the complex of work on plastering walls with clay are as follows:

• preparation of walls and other bases for plastering;
• preparation of the solution;
• plastering itself;
• finishing (iron coating with a thin layer of cement mortar, application of decorative gypsum plaster or clay-sand composition, painting).

Every task is completed between +5 and +30 °C with less than 80% humidity. For a solution without cement, you can use warm water.

Preparing the base

Before plastering, old clay plaster coatings or surfaces made of other materials need to be cleared of peeling areas, paint, varnish, and wallpaper—or better yet, the old plaster should be removed. A rough surface is required for the base: if the clay coating is thick, attach the mesh with dowels. If the base is made of brick or concrete, use laths or nails that are not driven all the way in for better adhesion.

Grease stains, rust, efflorescence, and biodeterioration foci are removed from the base. Primed walls are porous and readily absorb liquid from the plaster mass. It is required to dry for at least two hours following priming.

If required, seams in the brickwork and base cracks are widened and deepened to facilitate the easy filling of the clay solution. Beacons are installed on the walls if there is more than 2.5 cm of plaster solution applied. The base is wetted right before applying the solution.

Required tools and materials

Applying a clay coating can be done manually, mechanically, or with hand tools. Regardless, you’ll need the following painting and plastering supplies:

• container for diluting the composition;
• spatulas of several sizes;
• rule;
• graters;
• brushes;
• mixer.

Preparation of the solution

A solution with a volume ratio of 1:2 to 1:5 is the most basic kind. The following fillers can be added to the composition in addition to the ones already mentioned:

• cellulose;
• dolomite;
• quartz;
• sodium gluconate;
• calcite;
• magnetite;
• urea.

The sand and clay are combined after being sifted, but before being diluted. Gradually add water to adjust the consistency.

An additional method of mixing involves sifting the clay, then adding water and letting it sit overnight. Empty the extra water in the morning, mix the material, and then add sand in an empirically determined ratio.

Due to the rapid heat transfer through the coating, such a composition is typically only used for finishing work (a thin layer) and coating furnaces.

The second class of solutions (sans sand) uses sawdust. Although this kind of clay mortar composition is more difficult to apply, it is remarkably strong and has a low heat conductivity. In order to prevent sawdust from absorbing moisture from the clay solution, it is soaked before mixing. Because the sawdust fibers "play," altering the surface’s appearance, and the solution is not very elastic, this type of composition is not used for finishing. The solution’s plasticity is increased by the addition of horse manure.

Application of clay plaster

Applying clay plaster

The procedure for plastering is the same as for other compositions.

1. Moisten the prepared surface.
2. The solution is applied with force (to increase adhesion) with a trowel (bucket, spatula or just by hand).
3. The first layer of 10-25 mm thickness is not smoothed out, after application it is dried.
4. The next layer after application is leveled along the beacons with a rule.
5. Remove the beacons.
6. Fill the resulting grooves with the solution.
7. Rub the surface for whitewashing or wallpaper.

Once the clay walls have completely dried, the plastering can be completed. Whitewash and breathing paints are applied as a final touch. Putty can be used.

Natural material is safe for the whole family to use; it doesn’t trigger allergies. Kids enjoy creating sculptures. They will be able to express themselves and improve their motor skills through this activity. Their artistic errors won’t have a disastrous effect because badly organized content is easily fixed.

Decorative clay plaster

Finishing also uses natural plastic material, which lets you use your imagination freely. You can mold and form decorative clay plaster with your hands by using tools or makeshift objects. Stamps and rollers are also used for embossing. Different colored clay is frequently applied as a decorative coating. One can tint the ready-made white plaster mixture.

If you want to add environmental sustainability to your home, clay plaster is an excellent option. Since it is constructed of natural materials, it doesn’t emit any dangerous chemicals into the atmosphere. By doing this, you and your family may live in a healthier environment with better indoor air quality.

In addition to being environmentally safe, clay plaster gives your walls a distinctive appearance that enhances their character. Its earthy colors produce a cozy and welcoming ambiance. It’s also simple to apply and maintain, which makes it a useful choice for homeowners who value simplicity and beauty.

Additionally, you’re choosing clay plaster, which is a sustainable option. Compared to many other wall finishes, it has a lower environmental impact during production. Thus, you’re improving the look of your house while also making a positive impact on global health.

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