“Caeruleum” on Johannes Komersteiner\u27s altars

Potkraj 17. i početkom 18. stoljeća u Zagrebu i okolici nastao je veći broj oltara iste kolorističke zamisli, a svi se mogu povezati s naručiteljskom djelatnošću Zagrebačke biskupije. Sačuvani ugovori za polikromiranje triju oltara Johannesa Komersteinera ukazuju na to da je prepoznatljiv kolorit bio izričit zahtjev naručitelja, a analiza pigmenata pokazuje podudarnost upotrijebljenih materijala i tehnika.In the late 17th and the early 18th centuries, several wooden altars were erected in the territory of the present-day Zagreb. The altars were ordered by the Zagreb Diocese and made by sculptors from the workshop of Johannes Komersteiner and his heirs. In addition to the high level of sculptural shaping, these altars are characterized by a contemporary repertoire of ornaments, such as the recognizable weaves of the Baroque acanthus and the playful putto figures. The preserved contracts for the painting and gilding of some of these altars reveal that the polychrome appearance was the result of the work of not just one painting workshop, but rather at least two, those of Johanes Rosman and Bernard Bobić. The four preserved contracts for the execution of three altars in the Zagreb Cathedral – two of them signed with Bernard Bobić for the altars of the Holy Virgin Mary and St. Ladislaus, and two with Johanes Rosman for the altar of St. Emeric – reveal that the painters were asked to paint the altar blue and to gild it „in a mixed fashion, as necessary“, which indicates that there was a well-known kind of blue-and-golden di- chromatic appearance, a conventional colour distribution. The restoration and probing of layers of paint on these altars have confirmed that they were painted in the same fashion, that is, the fat surfaces of the background and the pillars were painted blue, while the ornamental applications were regularly gilded. Our conclusion is that this kind of polychromy cannot be linked either with the influence of Komersteiner’s workshop or with the painting work of Bobić and Rosman, but rather with the taste of the clients, clergymen of the Zagreb Diocese. The analysis of the material has established that the technology applied was also the same. The blue surfaces were covered with tempera with smalt pigment, while the gilding was always poliment. On some of the altars, in addition to smalt, a small quantity of arsenic can also be detected, visible on the micro-cross-section as a thin layer of underpainting made in auripigment. Future research encompassing a larger number of samples, not involved in this study, is needed to establish whether this underpainting occurred by accident or as a result of a technological process that was customary in this region in the given time period