During their lifetime, fragile stained glass panels get exposed to various factors that affect their state of preservation. The painted glass panels from the collection of the Pushkin State Museum of Fine Arts used to belong to different owners and were exhibited in different places. At the same time, it was only at the beginning of the 19th century when the stained glass conservation and preservation became a common practice. Most of the pieces from our collection came to the museum in a ruined state: with severely damaged lead cames, glass diseases, losses of glass and paint layers due to the abrasive cleaning in the past. The state of preservation, storage conditions and old restoration methods of stained glass panels have influenced contemporary approaches to their restoration and conservation.
The first attempts to restore medieval monumental stained glass were happening at the beginning of the 19th century and went hand-in-hand with the conservation and study of medieval architecture. Small-scaled Renaissance glass panels were also restored for the first time then, with the goal of selling them later to private collectors. At that time, the main aim of the restoration was to bring back the integrity of the stained glass. Having studied the traces of previous treatments, today we can distinguish two approaches that existed in the 19th century. According to the first one, a master would replace the corroded lead cames and try to make up for the losses of glass as smartly as possible, selecting fragments close to the main composition in the subject, colours, visual motifs, and glass thickness, trying to complete lost coats of arms with the help of the available reference materials. At the same time, a master would often paint over the glass.
The second method of restoration practised in the 19th century can be conventionally referred to as "commercial". In this case, for the sake of restoring the integrity of the object, any glass fragment without special distinction would be placed in the lead cames, which created a chaotic, distinct mosaic pattern. There are examples of both approaches in the collection of the Pushkin State Museum.
The systematic conservation of stained glass began after the Second World War. During the second half of the 20th century, conservators focused their attention on medieval stained glass, and only in the 1970s, there was a gradual inclusion of small-scale stained glass panels of the Renaissance and Mannerism in the conservation research, which needed a somewhat different approach and methods of conservation. The latter has not yet been established completely, which emphasizes the relevance of the pre-conservation studies of the stained glass panels from the Pushkin State Museum.
Conservation at the Pushkin State Museum of Fine Arts
Due to the fact that the art of stained glass was never widely spread in Russia, collections of stained glass in Russian museums are very rare. Until recently, there was only one established workshop for the conservation of stained glass with a good research base and a scientific approach in the country, at the State Hermitage in St. Petersburg.
A stained glass workshop with the necessary equipment and materials was put together at the Pushkin State Museum specifically for this project. The first priority was to design a conservation plan based on the experience of our colleagues from the workshops of the Hermitage (Saint Petersburg), the Cologne Cathedral (Germany), Vitrocentre (Romont, Switzerland) and the Metropolitan Museum of Art (New York, USA).
There are two main approaches to treating such pieces now. The first way includes removing old lead repairs holding together broken fragments of glass, and glueing those fragments together, while at the same time doing the retouches, replacing the lost fragments of glass and paint. This approach is aimed at the overall aesthetics, with it, the original appearance of the piece and its integrity are restored, and the elements that interfere with the image perception are removed. The second and more conservative method is to preserve the old cames and lead repairs, even if the lead fragments go across the images of faces, hands and inscriptions. The decision should be made in each individual case based on the characteristics of a particular panel: its state of preservation, how stable the cames and glass are, etc.
The choice of the conservation method is influenced by many factors, including the results of the studies, computer reconstruction of the panels and their general condition. Each of the 67 stained glass panels included in this project requires an individual approach.