Clay plaster

Clay topcoat plaster coarse with straw

One-coat topcoat plaster for indoor use. On clay undercoat plaster, sufficiently level masonry and other solid materials. The thickness of application is between 6 mm and 10 mm. Clay topcoat plaster with straw is the mortar for every surface texture, from rustic to smooth. The short-cut straw serves only a decorative purpose on the surface, it makes the plaster smooth and easily workable even for novices. The plaster is painted with CLAYFIX clay paints.

Type of clay plaster mortar
Clay plaster mortar for use as plastering mortar. Earth-moist 05.010 and 05.210, dry 05.012 and 10.112.

One-coat topcoat plaster for indoor use. Manual or machine plastering. On CLAYTEC clay undercoat plaster, suitable masonry and solid building materials.

Natural building clay up to 5 mm, mixed-grain washed sand 0-2 mm.
Grain classification, oversize grain according to DIN 0/2, < 7 mm. Barley straw fibres up to 10 mm.

Country of origin

Material properties
Drying shrinkage 2.0%. Strength class S II. Bending tensile strength 0.7 N/mm2. Compressive strength 2.0 N/mm2. Adhesive strength 0.15 N/mm2. Abrasion 0.6 g. Gross density class 1.8. Thermal conductivity 0.91 W/m∙K. µ value 5/10. Vapour adsorption class WS III. Building material class A1.

Supply form, coverage
Earth-moist 05.010 in 1.0 t Big Bags (yields 600 l plaster mortar, 60 m2 area at thickness = 1.0 cm)
Earth-moist 05.210 in 0.5 t big-bags (yields 300 l plaster mortar, 30 m2 area at thickness = 1.0 cm)
Dry 05.012 in 1.0 t Big Bags (yields 625 l plaster mortar, 63 m2 area at thickness = 1.0 cm)
Dry 10.112 in 25 kg bags (yields 16.7 l plaster mortar, 1.7 m2 area at thickness = 1.0 cm), 48 bags/pallet

Store in a dry place. Earth-moist, clay topcoat should be applied no later than 3 months after manufacture. In the case of dry goods, unlimited storage is possible.
In winter, earth-moist goods must be stored so they are protected from freezing, otherwise workability during frost is impaired.

Mortar preparation
Add approx. 10–15% (earth-moist) or approx. 18–20% (dry) of water with standard rotary drums, turbomixers and pug mill mixers, in small quantities also with the motor agitator or by hand. Information on the use of plaster machines can be found at

Plaster base
Clay plasters adhere only by mechanical force. The substrate must be stable, frost-free, dry, clean, free of salt, sufficiently rough and absorbent. If a primer is necessary, CLAYTEC RED (13.435-.430) is suitable. Clay undercoat plaster must be completely dry.
If necessary, the substrate may be moistened first (with a spray) to bind surface dust.

Application method
The mortar may be applied with a trowel or sprayed on with a plastering machine. Minimum and maximum application thicknesses are 6 and 10 mm respectively. The surface structure depends on the time of application and the tool used. In principle, the more the
plaster mortar has set by the time the surface is worked, the finer the structure will be. Rubbed surfaces are created using a sanding board of sponge, plastic or wood. Smooth surfaces are achieved by post-treatment with a spreader.

Working time
Since no chemical setting process takes place, the material remains workable for several days if kept covered. It can be kept in plaster machines and hoses for the same length of time.

After application, it is essential to ensure that drying takes place rapidly, e.g. by means of cross-ventilation (all windows and doors kept open 24 hours a day) or drying equipment. Under critical conditions, drying must be documented in accordance with DIN 18550-2. Details can be found there or in the CLAYTEC ‘Clay plasters worksheet’. We are happy to provide extra information.
Microbiological background concentration: Product with plant fibres, earth-moistened. For more details, visit, ‘Artikel Wohnung + Gesundheit’. We would like to point out that compliance with certain values cannot be guaranteed.

Subsequent processing
The surface may be coated with WHITE primer (CLAYTEC 13.415-.410) and CLAYFIX clay paint.

Sample application
In all cases, the suitability of the primer and thickness of application must be tested by means of a sample application of sufficient area. Compensation claims, unless they result from factory mixing errors, are excluded.
For further information, see the ‘Clay plasters worksheet’.




DIN 18945-47
ECO-INSTITUT schadstoff- und emissionsgeprüft

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