The paper outlines the experience of the technologists members of an International Complex Expedition for investigation photographing, documentation, conservation, restoration and exponing of the medieval (early Byzantine) fortress near Balchik. Concrete data of the technologies used and compositions for the re=pointing of stone-structure (acnus implectum), for the sealing and hydro-isolation of the upper horizontal layers of the wall and towers and for the making of artificial stone, necessary for the partial restoration of the western gate and its adjoining towers, are outlined.