Surface preparation:
To achieve the desired effect, the surface (base) should be a similar color to the plaster, and for light variants it should be perfectly white. It is recommended to prime the base with a white water-repellent primer that contains fine quartz sand.
For surfaces that absorb moisture, it is mandatory to apply at least 1-2 coats of primer. This way you protect the surface from moisture and achieve an even color with a rough base, which makes applying the plaster easy and pleasant.
Old wallpaper should be removed beforehand, and nails and other metal elements should be removed from the walls or covered with varnish to protect them from rusting. Areas with mold should be pre-treated with anti-mold preparations and primed with a 2nd layer.