The benefits of cement-free clay

Carrying out clay works with cementitious clay has many disadvantages. Reynchemie is one of the few suppliers that therefore produces clay without cement. Discover everything you need to know about using cement-free clay in this article.

What is kaleys?

Kaleien is an ancient technique where a lime mortar is applied to the wall with a block brush. The clay, in an off-white color or pigmented in mass, maintains the structure of the masonry but protects the surface from the weather and is perfectly permeable to vapour.

Kalei gives a house, outbuilding, garden wall... a very nice decorative finish and is also very durable.

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For new construction as well as restoration and renovation

Kaleien is a perfect technique for giving your existing home or building a completely new look. It is particularly popular for restoration works, valuable monuments such as farmlands, rustic projects and exclusive villas, but also comes into its own with modern, sleek buildings.

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Benefits of clay for your wall

✅ By finishing a façade with a lime mortar, it will be well protected and resistant to all kinds of weather influences such as rain, wind, snow and hail.

✅ Kalei can eliminate imperfections or damaged stones in the façade, while maintaining the façade structure perfectly.

✅ A polished façade is also an aesthetic hit. Thanks to kalei, you can create a characteristic, charming façade with an authentic and rural touch.

✅ The natural clay can possibly be finished with lime, siloxane or silicate paint, where many colors are possible.

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The many benefits of lime-based kalei

The use of natural hydraulic lime NHL 3.5 in our RC Kalei offers a number of important technical advantages:

The main advantage is the vapor permeability: the lime in clay provides excellent “breathability” so that moisture and salts can easily migrate out through the wall without further problems. Since the underlying moisture simply migrates and evaporates, mosses will never be able to gain a foothold. Lime also provides a mud-killing effect.

In addition, cement-free clay has a self-healing character and it remains a certain elasticity preserved so that shrinkage cracks are avoided.

Because lime, in contrast to cement, does not immediately reject water, it is typically obtained in rainy weather cloud effect due to the color difference between the dry and wet parts of the wall.

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The disadvantages of cement-based potash

Many clay systems are made from air lime or NHL 2 lime to which cement is added to achieve sufficient curing.

Such cementitious clay systems are absolutely not recommended on old masonry; they are less durable and the risk of cracks and salt efflorescence is high. The cement ensures that the clay has fewer vapor pumps, disrupting the building's water management.

Concretely, this means that the use of cement in clay leads to reduced vapor permeability, a higher risk of shrinkage cracks, no elasticity, sensitivity to salts and no mud-killing and self-healing properties.

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Application of clay or “clay”

Kalei should only be applied to an open, healthy, dust-free and unpainted mineral surface. Loose and old layers of plaster or paint must be removed. This is what RC Decap 1 appointed. Organic and atmospheric contamination can be easily removed with a product such as our universal green cleaner RC OS 2.

Moisture problems, such as rising and seeping in moisture, must be solved first and in a timely manner. Rising moisture should be treated with RC Drygel 80.

RC Kalei must always be applied to a damp surface. We always recommend 2 layers of 2 to 3 mm each. Cracks may appear in layers that are too thick; however, they can be closed with the second layer. Kalei can be applied manually strip by strip, with a block brush, and mechanically with a worm pump. When processing by machine, a final finish must be done with a damp block brush to achieve the desired stripe effect. More detailed user guides from RC Kalei can be found on our technical sheet.

Around 30 m² of clay per day can be installed manually. By using a worm pump, you can apply up to 150 m² of clay per day.

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Coloring

RC Kalei In addition to the natural color (off-white), van Reynchemie is also available in 29 other colors. To do this, consult our color chart. By default, pigment is supplied separately and is added to the mixing tub when making the clay mortar.

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Finishing options

Afterwards, it is also perfectly possible to apply protection. The calcareous façade can be treated with a hydrophobic cream (RC Hydro Cream 4), hydrofuge (RC 805 ECO) or an impregnating agent/anti-graffiti (ARC. 809 DAY). Post-treatment with these products can further protect your façade without reducing the vapour permeability.

An extra finish coat can be painted with siloxane paint (RC Siloxcoat), lime paint (RC Calco) or silicate paint (RC Silica Paint). The combination of RC Kalei with finish RC Siloxcoat is a very popular system and also has further advantages such as dirt-resistant properties, so that outgrowths are avoided as much as possible.

Finally, it is recommended to treat a skirting board at the bottom (~1m) with RC Siloxcoat whether RC Roof Acrylic. These paints offer optimal protection against splashing water.