How to work with clay plaster: prepare and apply the mixture with your own hands

For centuries, clay plaster has been a natural and multipurpose material. By controlling humidity and letting walls breathe, it not only provides a distinctive, earthy finish but also helps to create a healthy interior atmosphere. Clay plaster could be the ideal option if you want to give your walls a sophisticated yet rustic look.

You can accomplish a satisfying process by yourself when working with clay plaster. The steps are simple but need careful attention to detail, from mixing the mixture to painting your walls. The secret is to know the characteristics of clay and how to work with it appropriately, regardless of whether you want a more textured finish or a polished, smooth appearance.

We’ll go over everything you need to know to start using clay plaster in this guide. You’ll discover how to confidently mix the ingredients, prep your walls, and apply the plaster. You will be able to produce stunning, long-lasting finishes with a little bit of practice.

Where is clay plaster used??

For a long time, clay plaster was probably only used for indoor partition installation and stove and fireplace finishing. However, you can be positive that they are still in good use if you observe old buildings that have been plastered with clay compounds.

Cement-clay mixtures are frequently used in the masonry of red brick partitions, which are also incredibly durable. Furthermore, you can hang heavy racks on them without worrying about them toppling over, unlike delicate drywall.

Most frequently, both inside and outside the home, wooden, clay (saane) walls are plastered with a mixture of sand and clay. In theory, clay can be used to plaster any surface. The most important thing is to properly prepare them, choose the clay’s fat content, and keep the ratios of the additives (straw, sawdust, and sand) in the solution consistent.

Excess moisture can be absorbed by this eco-friendly material and released when needed. Designers and craftsmen are increasingly using flax or straw-filled clay plaster as a decorative finish because it looks unique.

Advantages and disadvantages

Clay plastering offers a number of benefits.

• Environmental friendliness; clay does not contain harmful impurities.
• Fire resistance: it is absolutely not afraid of fire.
• This material easily sticks not only to concrete or brick, but even to wood. In the latter case, shingles are used to secure it.
• Even a non-professional can work with a plastic clay solution.
• It is able to "breathe", that is, absorb moisture from the air and release it when the relative humidity changes, which is very important for creating a comfortable microclimate.
• Adsorption. It has been noted that allergy sufferers feel more comfortable in rooms finished with clay plaster. After all, clay is able to absorb odors and bind harmful substances.
• It costs absolutely nothing: you can dig it up with your own hands in the nearest quarry or in your garden.
• Good sound insulation and heat conservation.

Although clay plaster offers clear benefits, it also has drawbacks:

• Duration of surface drying – a layer only 1 cm thick will dry for 5 days. Thicker 5-10-centimeter layers dry for 2-3 weeks.
• Moisture capacity. Due to the ability to absorb water, clay surfaces need additional protection.
• Low strength. Of course, it cannot be compared with cement mortar. Clay is easily scratched and chipped.

Technical characteristics

Through the use of thermal conductivity After a gypsum-perlite solution, clay-facile coating comes in second with a thermal conductivity of 29 W/m × ° C. Clay has a thermal conductivity of 69 W/m × ° C in its pure form, which is nearly 1.5 times less than that of a cement-sand mixture.

Vapor permeability is another crucial plaster indicator. After all, in order to prevent condensation, moisture needs to be eliminated from the area. For clay, the coefficient of vapor permeability is 0.11-0.15 mg / (m * hour * Pa). This goes beyond just log walls. Clay is therefore excellent for plastering wooden houses.

Clay’s density, or the weight to volume ratio, is 1700 kg per cubic meter. Bricks have comparable densities.

For every square meter, 15 kg of clay plaster with a layer thickness of one centimeter are consumed.

Applying clay plaster to your walls is a gratifying and environmentally responsible way to give them a rustic, earthy look. You can use an original and sustainable material to transform your space by mixing and applying the plaster yourself with a few easy steps. This post will walk you through every step of the procedure, from choosing the best materials to evenly applying the plaster to guarantee a flawless finish. With a little practice, anyone can achieve the timeless, cozy look of clay plaster, whether they’re finishing a new wall or restoring an old one.

Which clay is suitable for plastering?

The composition’s ratio of sand to clay is directly influenced by the clay’s fat content. Sand is much more necessary for very fat clay. The ratios can be as low as 1:2 (for medium-fat clay) or as high as 1:5 (for clay-sand). Sand can never be added if the clay is extremely thin. Please be aware that you must measure out the components by volume rather than weight. For this, using a big jar or a bucket is more practical.

You must ascertain the clay’s fat content in order to choose the clay solution’s proportions. This is carried out in the manner described below.

Using four different types of the prescribed solutions, each with a different amount of sand, roll a small ball that is between three and four centimeters in size. Now, launch each of them from a distance of roughly one meter.

When the "correct" ball hits a hard surface, it shouldn’t deform too much or sustain any damage. The solution is too fat if it flattens. When it dries, it will crack. If it crumbles, the clay is too lean, and you should add more of it to the mixture to prevent the plaster from becoming brittle.

You can also use a clay ball that has been flattened and lowered by half on a hard surface to see if the solution is ready. Small cracks should ideally start to show up around the sample’s edges. You need more sand if they don’t show up at all. On the other hand, add clay if the cracks are deep.

Using the prepared solutions, you can attempt to roll out a long tourniquet that is 20–30 cm long and has a couple of centimeters of cross section. Make sure that such a tourniquet does not break after bending by experimenting with different ratios of sand to clay.

Counseling! Apply a thin layer of cement (iron) or paint to the clay plaster to keep it dry and extend its lifespan.

How to make a solution for plaster

Plaster can be prepared without the need for complicated tools. Consider using a large, old container, like a bath or trough. Even if a big volume is needed, you shouldn’t soak more than ten to fifteen buckets because mixing clay and sand will be challenging.

Soak clean clay for at least 24 hours, stirring it occasionally, without adding any soil or plant roots. It will be simpler to work with in this situation and to knead with your hands. Remove any extra water by draining. Eliminate any sizable clumps that have not been sufficiently moistened with water or plant matter. Prepare the solution by adding the necessary amount of sand, as we already know the required proportions and the quality of the clay.

Don’t add too much liquid at once; add it gradually. Knead the mixture until it reaches the appropriate consistency.

The preparation process can be greatly expedited if you have an electric drill or mixer. A concrete mixer is needed for big batches. By the way, drop a few stones or brick fragments into the water to break up the clay perfectly. They’ll assist in combining the solution and breaking up the clay.

Additives in the clay mixture

In order to strengthen the final plaster, asbestos, lime, or gypsum are frequently added to the mixture when plastering fireplaces and stoves. One tenth part of them is all that is needed. For instance, 0.1 part asbestos and 1 part lime are added to the mixture if the ratio of clay to sand is 1:2.

Counseling! Find out that stove laying does not involve the use of cement that degrades in the presence of extremely high temperatures. Just 1:3 ratios of clay (preferably fireclay) to sand. You can utilize 1:2 ratios for a tiny hearth.

Stove plastering frequently involves the use of fireclay, or white baked clay. It becomes fireproof and takes on the characteristics of stone after being exposed to high temperatures. It is ground up and added to solutions in a 1:3:1 ratio (clay, sand, and cement M400–500).

The amount of sand can be increased for fatty clay. Find out how much cement is needed by using sand as a base. In other words, more cement equals more sand.

If getting pure, unadulterated clay is impossible (and in certain places requires digging to reach), it’s safer to avoid taking a chance and buy pre-made plaster mixtures, which are particularly useful for laying bricks for fireplaces and stoves. After all, stoves constructed using a failed solution may begin to smoke when it fractures.

A great way to insulate a building is with sawdust added to clay mortar. The presence of lumber in the composition serves as reinforcement for the plaster layer in addition to enhancing the building’s ability to retain heat. Nevertheless, smoothing out such a mixture is difficult due to its lack of elasticity. As a result, the daub is frequently left unleveled. However, once dried, the sawdust plaster does not crumble and does not fear cracking.

Counseling! If the mixture is too liquid, just drain the extra water after letting it sit for a while.

For those wishing to give their walls a more organic, environmentally friendly finish, clay plaster is a great option. It can change any area and give it a cozy, welcoming vibe thanks to its earthy texture and breathability.

Although it takes some work to prepare and apply clay plaster, the results are well worth it. You can create a stunning and long-lasting surface by carefully combining the ingredients and applying them with care.

Recall that practice makes perfect. In the event that your first attempt doesn’t go as planned, don’t give up. You’ll quickly become an expert at working with clay plaster and give your house a special, personalized touch if you’re patient and persistent enough.

Video on the topic

Clay mortar for laying a stove Proportions of clay and sand for laying a stove

Proportions of clay and sand for laying a stove, fireplace, barbecue

Preparing a mortar for laying stoves

How to make a clay-sand mixture correctly

How to make clay mortar for laying a stove