DIY clay plaster: application and composition

You might be tempted to give clay plastered walls a try if you’ve ever appreciated their rustic charm. Not only is homemade clay plaster environmentally friendly, but it’s also surprisingly simple to do once you get the hang of it. This guide will walk you through the fundamentals of applying and composing clay plaster, whether you’re eager to get your hands dirty or simply want to add a touch of natural beauty to your home.

A basic mixture of clay, sand, and water is used to make clay plaster; additional ingredients are frequently added to enhance its qualities. It is easy to understand why this natural material has been used for centuries in many different cultures. Its breathable nature aids in controlling the humidity and temperature within your house, and its customizable nature allows for the creation of various textures and finishes.

To achieve a smooth, polished finish, we’ll go over how to prepare your walls, mix your own clay plaster, and apply the plaster in this tutorial. Along with some common mistakes to avoid, we’ll go over some advice on how to ensure the success of your project. You can create stunning, long-lasting plastered walls that express your sense of style and dedication to sustainability with the correct tools and methods.

Where is it better to plaster with clay?

The characteristics of clay influence the decision to use it as a finishing material. as well as the potential applications for it, should the material’s intrinsic drawbacks permit them.

It is advisable to take into account the technical attributes and features of clay plasters in this context.

Advantages.

Clay plaster offers a number of special benefits. The primary one is application simplicity. Applying clay plaster on your own is the most successful method because other binders are more "capricious."

However, there are additional appealing qualities:

1. Cheapness. An indisputable fact even for ready-made clay mixtures. And if you bring them directly from the quarry and prepare them yourself, you can get them almost for free.

This extends to ornamental clay plaster as well.

1. Moisture capacity. The main technical, construction advantage.

Because clay absorbs moisture from the air in relatively large quantities, it helps to maintain a comfortable microclimate in a room with drops in humidity.

Clay plaster softens the abrupt changes in humidity by releasing water molecules gradually once equilibrium is restored.

1. Thermal conductivity.
2. Adsorption. Plastering with clay is healing, it interacts with active substances and binds them. In other words, clay plasters absorb harmful substances without “releasing” them back into the room.

Allergy sufferers have taken up residence in this property, finding that a home with clay plaster makes them feel lot better.

1. Elasticity clay rocks allows you to plaster heated structures with them (stoves, fireplaces, heating shields, chimneys).
2. Environmental friendliness. Natural sedimentary minerals do not contain harmful substances.

Clay is an eco-friendly material that is used for laying and finishing fireplaces and stoves, as well as plastering damp but not wet rooms.

Flaws.

Any property can be referred to as neutral in general. Under specific circumstances, they may turn into benefits or drawbacks.

1. Water capacity. Saturation with water molecules changes the structure of the clay. This leads to a change in its technical characteristics:

• Strength and hardness are reduced;
• Swelling leads to an increase in volume and mass;
• Soaking disrupts the integrity of the layer, which changes its geometric configuration – it is deformed;

1. Shrinkage is a consequence of swelling. Clay is so plastic that it shrinks gradually, it does not break. However, sudden drying can cause destruction (cracks, craquelure). Clay mortar for plastering walls is used with a filler, which increases the strength of the layer.
2. Thermal conductivity. For comparison: cement-sand plaster – 1.2 (W / m2K), cement – 0.93, lime 0.698, gypsum – 0.3. Clay – 0.7-0.9. Slightly "warmer" than cement. However, this property is used in finishing heating shields – the better the plaster conducts heat, the higher the heat transfer of the stove.

Gypsum is three times less thermally conductive than lime, which helps to better insulate the wall from heat loss. True, this indicator is not essential when the plaster is thin.

Strength is the main disadvantage. Compared to cement plaster, clay plaster is comparatively pliable, prone to scratches, and chip easily.

In contrast to cement plasters, clay plasters are "colder" than gypsum and not as hard. While they can be used in conjunction with other binders, they are not appropriate for finishing basements.

There are numerous types of clays based on the amount of impurities and the mineral makeup of the material. Red and white are the most popular colors in Russia.

For DIY clay plaster enthusiasts who want to give their walls a distinctive, organic touch, this is an excellent option. In this post, we’ll look at the fundamental ingredients of clay plaster and how to apply it properly. You’ll discover easy, step-by-step methods to use this environmentally friendly material to makeover your space, from blending the proper amounts to getting a smooth finish. Get useful advice to ensure the success of your plastering project, regardless of your level of experience.

Fat content and its definition.

The adhesiveness of clay is determined by its fat content, which can range from fat to lean.

Because lean clays have a low binding capacity, they are not used in construction. These clay plasters don’t crack much when they dry, but anything made with them has poor adhesion, is easily broken by mechanical impact, and gets moist.

To prevent it from crumbling, it is crucial to use non-depleted clay for plastering the walls.

Sand and fat clays are combined in a mixture. They crack as a result of large, uneven shrinkage, which makes separate use impossible.

Making a clay solution based on the ratio of water, sand, and clay is not possible. The fat content of the binder, which determines the proportionate ratio of ingredients, determines its quality.

Determination of fat content.

The only accurate method for determining the material’s adhesive saturation is a laboratory study. However, there are sufficient methods to estimate the fat content:

1. Ball. It is necessary to make several balls of a diameter. 50 mm with different amounts of sand and, without drying, “drop” them on the floor from a height of 1 m. If the ball cracks badly, delaminates or even crumbles, then it is made of a weak, lean solution. If it does not fall apart, but is strongly flattened – too fat.

Normal clay will develop tiny cracks but will still hold its shape and integrity.

The control sample can be "crushed" to one-third of its height with a plank instead of having to be dropped from a height.

1. Flagellum. From the prepared solutions of different saturations, roll out a flagellum (“sausage” with a thickness of approx. 1-1.5cm). The sample is wound on a wooden cylinder with a diameter of. 50mm (a shovel handle will do).

A solid solution should have some small fissures but still be cohesive. Plastering walls is appropriate use for this clay solution.

1. Tool. The solution is scooped onto a (clean) trowel moistened with water, which is not quickly unrolled so that the mixture slides off. The quality of the material is determined by the trace left on the metal by clay: a completely clean trowel – a thin solution, a very dirty tool – a greasy solution.

A typical mixture creates tiny traces and tracks.

Sand is added until it "rustles" on the metal tool’s surface, which is how some craftsmen tell when the clay solution is ready. But this is a route that only "pros" can take.

Applying clay plaster by hand is similar to professional work because of its features that let you work slowly, which is crucial for a beginner.

How to prepare clay.

The lumps are broken up, put through a fine-mesh sieve, and left in water for one to two days. The mixture will warm up but not dry out if the trough is placed in the sun and covered with a film to expedite the soaking process. Because hot water has a lower viscosity, it can more easily pass through the particles of rock.

Obtaining fine clay.

Dispersion determines the properties of clay, including its capacity to hold moisture. For this reason, masters of old advise preparing clay for later use by pouring it into shafts no higher than a few meters and moistening it. When defrosting in the winter, the mass expands and becomes much less rigid. This type of material is less likely to crack and is more pliable, pleasant, and workable. This is particularly crucial when making glossy, ornamental clay plaster.

It is preferable to use distributed clays that have been manually or by defrosting ground, when plastering stoves. In order to allow the brick to emit heat freely, the heating shield finish should have a minimal thickness.

Preparing the solution.

Once the amount of fat in the clay has been determined, choose the appropriate sand-to-clay ratio and proceed to prepare the solution.

1. Clay. By the time of mixing, it should be completely soaked, have a uniform structure without solid particles, lumps and debris.
2. Water. Excess water from the trough in which the clay was soaked is drained. Otherwise, the solution will be too liquid.
3. Sand. For rough, leveling plaster, sand is sifted through a sieve with 2-2.5 mm cells. For finishing coating, it is better to sift through a millimeter sieve.
4. Other fillers. Clay plasters of coarse composition, thrown on the lath during the construction of adobe walls, are mixed without sand, but with straw. The mass is mixed with feet, trampling in a trough.

After combining clay and straw in a sizable level pit and trotting a horse through it, a sizable amount of solution was produced.

• Sawdust. A shorter and more convenient reinforcing filler. Significantly reduces the thermal conductivity of the plaster, making it "warmer". A layer of clay-sand mortar is applied on top for careful leveling.
• Perlite. Insulating filler. Requires careful work, since it flies apart very easily (too light).

The prepared mass has an endless shelf life; its viability is solely dependent on the rate at which water evaporates.

In addition to sand, reinforcing additives like straw, sawdust, pine needles, synthetic fibers, and perlite can also be used as filler for clay plaster solutions.

Application of clay plaster.

Plastering and wall construction (i.e., adding thickness) both require the use of clay. Walls with a steep slope can also be leveled using sawdust or clay-straw mortar. The recessed areas are shingled for this purpose. For reinforcement, debarked round timber and wooden slats are utilized.

The solution is applied manually by "throwing" it onto the wall in the appropriate location. Once the layer gets thick enough, a wooden float that has been heavily moistened is used to level it.

Compared to other binders, clay dries more slowly. It takes two to three weeks for thick leveling clay plaster (5 to 10 cm thick) to dry. This is among its drawbacks.

The leveling layer is followed by a clay-sand mixture finishing layer. It is applied thinly and dries more quickly.

Plasters can be used as a finishing touch on additional binders. For instance, clay and gypsum plaster blend in perfectly.

How to improve a clay solution.

The two main drawbacks of a mixture based on clay are its slow drying time and relatively low strength. The solution to the problem is as simple as adding cement to it. Clay plaster is composed in a more dependable way. Additionally, environmental characteristics are not diminished if the amount of cement is not significantly reduced (one part of cement for every nine parts of clay). But clay plaster is strong, dense, and long-lasting, and the wall dries more quickly.

Is it worth using clay at all?

Only contemporary, "bought" mixtures are acceptable. However, there are a few circumstances in which clay is most evident:

1. Saving. The price of clay plaster gravitates to zero. It is literally everywhere, only a few meters from the soil surface. Its cost is limited only by the cost of production and transportation. Fatty clay consumption is comparable to cement consumption.
2. Deep bias. With significant curvature of walls (5-7cm)-fighting the simplest adequate output. Moreover, the work is easily done with your own hands. Alignment with other materials is better to order from specialists.
3. Adobe and settled structures, wooden houses. Such structures are plastered only with clay solutions. Otherwise, you will have to buy sheet finishing materials costing 300-600 rubles. per square month, order work from a finisher. Another 300-600 rubles. per sq. m.
4. Poor ventilation. In “park” rooms, thick clay plaster can dry out the air. A kind of bonus material that costs 0 rubles. per m2.

Any base—boards, wood, adobe, cinder block, brick, or cellular concrete—can be covered with clay plaster. Clay is an anomaly in this regard.

Aspect	Description
What is Clay Plaster?	Clay plaster is a natural wall finish made from clay, sand, and sometimes straw. It’s eco-friendly and has been used for centuries.
Benefits	It’s breathable, helps regulate indoor humidity, and is non-toxic. It also provides a unique, earthy aesthetic.
Preparation	Mix clay with sand and water to create a workable consistency. Add straw if you want extra durability.
Application	Apply in thin layers using a trowel. Smooth out each layer before applying the next. Allow each layer to dry before adding more.
Drying Time	Drying times can vary but usually take a few days. Ensure good ventilation for faster drying.
Maintenance	Clay plaster is durable but can be cleaned with a damp cloth. Reapply a fresh layer if needed.
Tips	Test a small area first to get the feel of working with clay plaster. Keep your tools clean and work in manageable sections.

An eco-friendly and satisfying way to add a distinctive, natural finish to your walls is through do-it-yourself clay plastering. Your home’s appearance and feel can be improved with a lovely, breathable surface made from easily accessible, low-maintenance materials. Because clay plaster can be applied in a variety of textures and colors, it is a popular option for people who value adding a unique touch to their living spaces.

Even for novices, applying clay plaster can be a simple procedure. You can achieve a smooth, long-lasting finish with a little planning and attention to detail. Plaster must be properly mixed and applied in thin, even layers to prevent common problems like uneven coverage or cracking. To achieve a professional-looking result, proper application technique and surface preparation are essential.

Beyond its visual appeal, clay plaster has a number of useful advantages. It is a healthy option for your home because it is a natural material that enhances air quality and helps control indoor humidity. Furthermore, clay plaster’s sustainability and long-term worth are increased by how simple it is to maintain and repair.

In conclusion, clay plastering yourself is a doable project that can give your walls a hint of organic elegance. Any do-it-yourselfer can benefit from the beauty and advantages of clay plaster in their own home with a little imagination and hard work, so it’s a worthwhile project.

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