Yes, earth block masonry can be painted, plastered, or otherwise surface-treated.
As a general principle, vapor permeability should be maintained. Clay paints and clay plasters are particularly suitable, as they preserve the capillary-active and moisture-regulating properties of the earth. This ensures that the benefits such asmoisture buffering and a balanced indoor climate, remain fully effective.
A light surface wash is also possible. By gently drawing a damp sponge over the surface, the joints can be visually softened, turning the masonry into a calmer, more continuous surface without altering its natural color.
In certain applications, it may be advisable to use more water-resistant finishes. Lime plasters or mineral tile finishes, for example, are well suited for bathrooms, kitchens, or other areas subject to higher moisture exposure. In such cases, careful detailing is required to prevent persistent moisture from entering the structure.
Other mineral coatings are generally compatible. Highly diffusion-resistant paints or dense coating systems are less suitable, as they may impair the moisture-regulating performance and recyclability of the material.