The primers recommended in the decorative wall plasters product-pages are intended for an ideal substrate such as new plaster / washable paint / gypsum / plasterboard-coated walls. Other types of substrate, such as old walls, tiled or marble surfaces will need a different substrate treatment. Please refer to the instructions in the TDS.
On mineral wall plasters the application of a sealer is optional. The only environments in which sealers are necessary are: wet areas (inside showers, saunas); or in areas subject to spillages, such as: bathrooms, kitchens splash back walls. On exteriors, sealers are important only in heavily polluted cities. A varnish is necessary on Travertino, Pastellone, Petrae, and Beton Stucco when these are used as furniture coatings.