1. Preparation of the substrate

The substrate must be clean, dry, sound, and uniformly absorbent. Remove dust, grease, loose layers, wallpaper adhesive residue, and other substances that reduce adhesion. Repair any damage as necessary. Gypsum board that has been fully plastered must be properly prepared and sanded.

2. Primer preparation

Mix 250 g casein powder with about 3 liters of cold water, using a hand mixer. Let the mixture stand for at least 30 minutes, then mix again and while stirring constantly, add another 5 litres of cold water. When preparing smaller quantities use about 32 ml water per gram of powder in two stages.

3. Application

Apply primer using a large soft brush, always working from bottom to top. The surface should be evenly saturated, but avoid allowing excess material to accumulate. Remove any wet, shiny excess before it dries using a brush or a clean cloth.

4. Drying and conditions

• Working temperature min. +8 °C
• Drying time approx. 8 hours (+20 °C)
• After drying the surface can be painted with lime, clay or casein paints, or coated with a mineral plaster.
• Mixed primer must be used on the same day.

5. Maintenance and recommendations

Clean the tools with warm water immediately after use. Store the powder in a dry, frost-proof place. Before treating larger surfaces, it is recommended to test a small area to assess the absorbency of the substrate and the amount of material needed.

HA:IM recommendations

Casein primer is the ideal choice before applying natural lime-, clay-, and casein-based finishing materials. A properly primed surface ensures more even drying, better adhesion, and helps achieve a high-quality, long-lasting finish while preserving the structure’s natural breathability.