An age-old method that has endured is clay plastering, which provides a natural and environmentally responsible way to finish your walls. It offers a distinct look that contemporary materials frequently can’t match in addition to being sustainable. Clay plaster can be a great option for both remodeling an old house and giving a new one character.
The use of clay plaster is very advantageous. Because of its breathability, indoor air quality is enhanced and humidity is better managed. It’s also non-toxic and composed of easily accessible materials, which makes it a healthier choice for your home. You can accomplish professional results on your own with a little help.
We’ll walk you through the clay plastering process in this guide. You’ll learn all you need to know to get started, from priming your surfaces to blending the ideal plaster and smoothly applying it. Let’s get started on how to make stunning, long-lasting, and environmentally responsible clay-plastered walls by hand.
Step | Instructions |
1. Prepare the wall | Clean the wall surface of any dirt and loose material. Wet the wall slightly to help the clay adhere better. |
2. Mix the clay plaster | Combine clay, sand, and water until you achieve a thick, smooth consistency. Use a paddle mixer for even blending. |
3. Apply the base coat | Spread a thin layer of clay plaster onto the wall using a trowel. Make sure it covers the entire surface evenly. |
4. Let it dry | Allow the base coat to dry completely. This can take several days depending on the humidity and temperature. |
5. Apply the finish coat | Once the base coat is dry, apply a second, thinner layer of clay plaster. Smooth it out with a trowel for a clean finish. |
6. Smooth the surface | Use a damp sponge or trowel to smooth out any rough spots or imperfections in the finish coat. |
7. Allow to dry | Let the final coat dry completely. This may take a few days, and the drying time can vary. |
8. Final touch-ups | Inspect the wall for any cracks or imperfections. Fix these with small amounts of clay plaster and smooth them out. |
A natural and affordable wall finishing method that provides exceptional breathability and visual appeal is clay plastering. With the correct tools and methods, you can do it yourself with ease. This tutorial will lead you through the process of applying a smooth, long-lasting clay plaster finish. You’ll discover how to makeover your walls using this adaptable and environmentally friendly technique, from mixing the clay to applying and polishing the plaster.
- Types of clay-based plasters
- Technical characteristics of clay mortar for plastering walls
- Advantages and disadvantages of clay compositions
- Which clay is suitable for plastering
- Fat content and its definition
- Obtaining fine clay for plastering
- Instructions for applying clay plaster to the walls of a house
- Proper preparation of the base
- Necessary tools and materials
- Preparation of the solution (how to mix the clay correctly), proportions
- Application of clay plaster – coating
- Clay decorative plaster
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Types of clay-based plasters
In addition to kaolin, other mineral substances are also incorporated into the composition of clays. Additives change the mass of clay’s color. Organic components and tiny bits of rock or mineral are frequently found in the compound as impurities. The technological properties of clay are influenced by its chemical composition.
- blue;
- white;
- red;
- gray;
- yellow;
- black.
Dry coloring can be added to the diluted building mixture to give the clay mortar a different shade.
Because the clay composition lacks the necessary strength, it can only be used for interior decoration when lime-gypsum or lime mortar is applied on top. The mixture is prepared with the addition of lime, cement, or gypsum to increase its strength.
The clay mass is classified into the following types based on the type of combined binder:
differ in waterproof characteristics, strength, durability, ease of application. The material can be used for decorative plastering, creating original design solutions indoors. The composition is distinguished by a variety of colors, reliable adhesion to the surface, simple decorative processing.
- standard;
- decorative.
The filler content of various clay-based finishing material types varies. Wood sawdust, chopped straw, dried pine needles, artificial granules, and fibers (polystyrene foam) can all be added to increase strength.
Ideal for completing the facades of buildings. The properties of a mortar consisting of fiber-infused clay and sand exhibit enhanced durability, resilience against sun exposure, and elevated moisture content during rainy seasons.
Technical characteristics of clay mortar for plastering walls
The thermal conductivity of sawdust added to clay plaster is 29 W/m2 °C. Because the plaster has a high vapor permeability coefficient, wooden wall panels can be processed using this material. The mass of clay has a density of 1700 kg/cu. m. The plaster application thickness of 1 cm will result in a consumption of 15 kg per square meter. The substance has thermal stability.
- construction and finishing works;
- plastering of fireplaces and stoves;
- design and insulation of external wall panels in private buildings;
- interior finishing works in rooms and outbuildings.
Since clay has poor water resistance, it’s crucial to plan for the installation of extra waterproofing when decorating facades to avoid the decorative layer deforming due to precipitation and high air humidity.
Advantages and disadvantages of clay compositions
- wide selection of clay mixtures, differing in color solutions, structure;
- ecologically friendly composition of the material;
- high heat-protective characteristics;
- high vapor permeability ensures a comfortable microclimate in the premises;
- affordable prices;
- composition with fireproof characteristics;
- increased sound insulation of the room;
- easy preparation of the solution for plastering and ease of application of the mixture;
- high plasticity of the composition;
- waste-free use of the solution (the remaining mixture can be stored indefinitely);
- resistance to moisture;
- easy restoration after damage, cracking of the coating;
- the ability to vary the thickness of the decorative layer;
- long service life;
- the ability to create textured images of varying levels of complexity;
- it is permissible to use for decorating wooden surfaces.
- at high humidity, damp air, the coating can be damaged;
- for a dense layer of plaster to dry, in some cases, it will take up to 1.5-2 months;
- the minimum layer for application is 1 cm;
- when the material dries, increased shrinkage is noted;
- when preparing the composition, it is important to select the optimal recipe for climatic conditions.
Which clay is suitable for plastering
When choosing clay for plastering, factors such as the amount of impurities, plasticity, and fat content are taken into consideration. Lean clay is not advised to be used for this task. A light material with a plasticity level of up to 0.27 or a heavy material with an indicator of more than 0.27 would be ideal. It is preferable to use clay with a medium fat content, density, and stable plasticity. Applying and drying heavy clay compositions can cause cracking.
Fat content and its definition
The natural composition of clay varies in terms of fat content; it can be lean (having a high sand concentration) and medium fat, or fatty with a lot of silt and clay particles. An experiment is used to determine the parameter. The amount of fat in the clay mass determines the proportion of sand to clay in the plaster. The fatty material will require more sand. The solution’s proportions can be 1:5, 1:4, 1:3, or 1:2 in relation to the ratio of river sand to clay. Sand won’t need to be added to lean clay types because of their high density.
It is required to prepare various types of solutions based on the component concentrations in order to ascertain the ideal proportions. Three to four centimeter balls are rolled from various kinds of material. Next, every copy needs to be hurled from a height of one meter. After falling, the ideal composition shouldn’t alter in shape. The excessively fat clay in the solution causes this plaster to crack when it dries if the mass is flattened. Since the crumbling balls were composed of lean clay, higher component proportions are required to produce plaster of superior quality.
Obtaining fine clay for plastering
The clay mass is categorized into highly plastic and non-plastic levels based on its degree of plasticity. The material’s dispersion and mineralogical makeup have an impact on this indicator. In order to produce fine clay for plaster application, the mass needs to be evenly distributed throughout the area, with a layer as high as one meter. After that, the composition is moistened and placed outside for the winter.
The mass’s plasticity rises as the frozen material loosens. The material can be applied to furnace coatings, interior walls, and facade decorative finishing.
Instructions for applying clay plaster to the walls of a house
- preparation of walls and other surfaces;
- making a solution from sand, clay and other components;
- plastering surfaces;
- finishing includes applying a thin layer of cement-based mortar for fixation, decorative gypsum plaster, and tinting the surface.
Expert recommendations state that the air should be at least 80% humid and that the work should be done at a temperature of +5–+30°C. Just warm water should be used to prepare the solution.
Proper preparation of the base
Clay plastering necessitates wall preparation. Remaining paint, varnish, wallpaper, and old coatings are removed from the surface. There should be some texture to the base. In order to apply a thick layer of plaster to concrete or brick walls, experts advise fastening the metal reinforcing mesh using dowels.
If required, clean off any rust residue, oily stains, and any fungal damage. Wall panels with pores can be primed. After that, the surfaces are dried for two hours. Base cracks and brickwork seams are widened (deepened, widened) in order to receive a clay mixture. Beacons are affixed to the surface when plaster layers are thicker than 1.5 cm. The areas are moistened with clean water before plastering.
Necessary tools and materials
- tank (tank or.p.) for mixing;
- brushes;
- leveling rule;
- spreaders of different shapes and sizes;
- graters;
- construction mixer;
- shovel for loading the solution ingredients;
- sieve for sifting river sand;
- measuring container;
- hammer drill;
- screwdriver for fixing the reinforcing mesh;
- electric drill with special attachments, etc..
- dowels or nails for fixing the mesh;
- sand;
- sawdust or fibers;
- clay;
- steel mesh;
- cement powder or gypsum for fixing the final layer.
Preparation of the solution (how to mix the clay correctly), proportions
Depending on whether the plaster is intended for an interior or exterior facade, the mixture is prepared differently. Clay and river sand are combined in a standard solution in a ratio of 1:2 to 1:5. Fillers such as urea, sodium gluconate, magnetite, dolomite, and crushed quartz can all be utilized. d. Sand is sieved prior to composition dilution.
The composition is gradually supplemented with small amounts of ingredients to control the consistency of the building mixture. It is required to soak the plant material in water before incorporating it into the solution when utilizing sawdust.
Application of clay plaster – coating
It is necessary to wet the surface with water before applying clay plaster. After that, the solution needs to be distributed by hand or applied to the wall using a trowel or spatula. The initial plaster layer should not be thicker than 10–25 mm. The surface has been dried and smoothed. The following layer is then put on and smoothed out. After removing the beacons from the wall, clay composition is poured into the remaining grooves.
Once the prior coating has dried, the finishing layer is applied. Plaster walls and other ceilings are scraped down in preparation for additional putty, wallpapering, or whitewashing. Dyes or materials for whitewashing are used as decoration materials.
Clay decorative plaster
Plaster with a clay base is a plastic that can be applied as the final decorative layer. It is possible to shape this composition to play the image. Stamps, rollers, and other tools are used in the work. Using various shades of clay is ideal for decorating surfaces. Plaster can be tinted white.
Venetian decorative plaster is available in three texture options: structural, textured, and smooth.
- stone (marble, onyx, granite);
- wood of different species (oak, nut, pine) or the surface of trees after bark beetle;
- sand and chips of different rocks, particles can be of different sizes, sand fragments can be used to design sections of the wall;
- by adding acrylic particles to clay, it is possible to achieve a velvety, velour, silk texture.
When designing unique interiors,
The material is applied while keeping the necessary humidity and temperature levels for artificial cracking. The varnished clay surface has a network of cracks that reappear after drying.
Ideal in rooms with natural materials. In order to create designs in the Art Nouveau, Provence, Mediterranean, and Renaissance styles, experts advise utilizing fragments coated in textured clay.
You could make a replica of stone or brickwork. Wall panel decoration features appear in loft, country, and Provence interior designs as well as modern ones.
Used to decorate spaces in industrial, loft, and high-tech styles. We add more ingredients to the clay solution. Brick panel design is blended with concrete coatings.
- Gradient coatings with the effect of satin, wet silk, reproduction of plant patterns on the surface look organic in the living room.
- Decorative plaster with imitation of stone, bricks of different types of masonry, boulders can be used in the hallway.
- In the study, a single-color plaster can be complemented with an insert with painting, gilding.
- For the dining room or kitchen, plaster imitating marble, variegated granite, wood (light types of oak, beech, birch) is optimal. In places with high humidity, the coating should be treated with a waterproof material.
- Plaster with a patination effect and reproduction of antique stonework looks great on the porch, staircases, in entrance groups.
- In the children"s room, a plaster supplemented by elements of artistic painting, airbrushing, looks original.
- The design of glazed balconies and loggias is carried out with compounds with water-resistant characteristics and resistant to temperature changes.
Finishing your home with clay plaster is a satisfying and sustainable option. You can lessen your carbon footprint and create a healthy indoor environment by utilizing natural materials.
We have discussed the procedures for preparing and applying clay plaster throughout this article. For a smooth and long-lasting finish, every step—from assembling the necessary supplies to perfecting the method—is essential. Recall that practice makes perfect, so don’t give up if your initial effort isn’t perfect.
You can give your walls a lovely, rustic appearance by adhering to the suggested guidelines and tips. In addition to the satisfaction that comes from a job well done, clay plaster has many advantages, including breathability and natural beauty.
With patience and an embracement of the process, you can soon have walls that capture the warmth and allure of a natural clay finish. Cheers to plastering!