Metal, paper, glass: perspectives on a stained glass panel and other objects in Stanford Libraries Special Collections
Left, Buckminster Fuller bronze life mask by Ruth Asawa, circa 1992, M1823; Center, [Die ghetijden van onser lieuer vrouwe[n] : fragment]. Paris: Widow of Thielman Kerver, 1533?]; Right, Leaded stained glass plate of St. Eustache, late 19th or early 20th century, M2336
Apart from traditional book and paper collections, unique objects in Stanford Libraries Special Collections embody material and cultural histories and can serve as rich primary sources. One such object is a stained glass panel of uncertain provenance that was sent to Conservation for protective housing.
In his introduction to Significance of Primary Records (Modern Language Association, 1995), textual critic and bibliographer G. Thomas Tanselle wrote:
“All artifacts—not just books—can be studied as physical objects to discover two major classes of historical information that can influence the interpretation of any visual or verbal symbols present on the objects. One class relates to their production history, to the techniques of their manufacture; the other focuses on their postproduction history, on the implications of their physical appearance once the objects were created.... Every object, whether or not it was intended by its producers to have a utilitarian function, can be looked at for whatever aesthetic value it may possess."
This three part series will present conservation and curatorial perspectives on various objects in the collections stemming from an inquiry into the stained glass panel mentioned above. In part one, I will introduce the Conservation Department’s approach to working with objects and describe the history and material composition of this panel. In part two, Kathleen Smith, Curator of Germanic Collections & Medieval Studies, will weigh in with curatorial perspectives and describe some other unusual acquisitions that have needed attention from the Conservation Department. In part three, Conservation Technician Sarah Newton, our collections storage genius, will expand on the Department’s work with collection objects.
Special Collections Objects in the Conservation Department
In the Stanford Libraries Conservation Department, we provide direct conservation treatment and specilaized storage for books and paper, and care for other unique collection objects by making protective enclosures and specifying handling procedures. If an object needs to be stabilized or conserved for an exhibit or research use, we contract with a conservator in the appropriate specialty area.
A few examples of objects that have passed through Conservation are Buckminster Fuller’s metal and plastic models, oil paintings used as photo backdrops from the Wylie Wong Photo Studio, and computer hardware from the Cabrinety Collection.
Books are usually paper based but they are also composite objects. Metal clasps, as seen below, parchment pages and wooden boards are found in early codices. Conservation enclosures are designed and adapted to accommodate the materials. For example, when making a custom cloth-covered box for a book with metal clasps, we use wheat starch paste instead of our usual polyvinyl acetate which could corrode the metal.
Autores historiae ecclesiasticae, Basileae: Froben,  (Stanford Libraries Department of Special Collections, BR141 .R44 1535 F)
A Leaded stained glass panel in Stanford Libraries
Leaded stained glass panel of St. Eustache, late 19th or early 20th century, (Stanford Libraries Department of Special Collections, M2336)
This panel, measuring approximately 8 by 12 inches, was sent to Conservation for a custom box by Manuscripts Accessioning Manager Christy Smith. The horizontal crack in the glass was also a concern. Though the glass is cracked, it is firmly set in the lead matrix. If this panel were to be exhibited, or if the cracked glass unstable, we would consider contracting with an objects conservator for evaluation and treatment.
For storage and safe handling, we constructed a mat board frame to cover the outer lead border. This allows patrons to handle and view the panel, without touching the lead, in either transmitted or reflected light. When holding it up to a light source, the panel can be experienced as the artist intended -- in a window with transmitted light. In reflected light, historic techniques can be distinguished, and the material composition better understood. The panel and mat board support are stored in an archival flat box with a support piece that fits inside the window mat and under the glass itself. The glass rests on the support so there is no chance of the cracked area slumping in storage.
Based on the image of the stag, the figure depicted in this panel was initially identified as Hubertus, patron saint of hunters. When Kathleen Smith proposed writing about this as a shelter in place project I decided to reach out to Virginia Raguin, a Professor of Art History at Holy Cross College, to see if we could learn more. Professor Raguin has written extensively about historic stained glass. I knew her as a student and through work in stained glass-historic building preservation. Professor Raguin quickly identified this image as the 2nd-century Roman martyr St. Eustace, a saint associated with hunting, and its direct inspiration as the figure on the right in the Paumgartner Altarpiece by Albrecht Dürer (circa 1500).
Paumgartner Altarpiece by Albrecht Dürer (circa 1500). Left panel, Saint George (Stephan Paumgartner); central panel, Nativity; right panel, Eustachius (Lukas Paumgartner).
This work is now in the Alte Pinakothek in Munich. Its history provided valuable clues about the creation of this stained glass panel. Professor Raguin shared the following:
“The right panel of the triptych is labeled St. Eustache. Note that the image was altered in the early 17th-century and the additions only removed in 1903. Thus, your figure is later. I would guess that it is German, given the high quality of the painting. It would make sense that a glass painter would be moved by the restoration of so handsome a painting – AND a national treasure that he would make a panel based on the work. It is possible that he envisioned a client interested in hunting.”
This information led us to the correct identification; however, St. Eustace and St. Hubert are both important saints for Southern Germany, with a long tradition of association with hunting, so it’s understandable that they are often conflated. Kathleen will expand on this in Part 2!
Stained Glass; History, Materials and Techniques
As a library collection item, this panel depicting St. Eustache is an interesting object for study, not only for its reference to the Dürer altarpiece, depiction of a hunter’s saint but also for the material study of stained glass. Although from the early 20th-century, this panel makes use of techniques dating as far back as the 12th-century. The image uses a neutral color vitreous paint applied to the surface of the glass and then fired for permanence. The glass itself is a red flashed glass that became common in the later 14th-century, and the yellow color a result of silver stain, an innovation of the early 14th-century.
A detail of a large window dated 1520 in the church of Saint-Gervais-Saint-Protais in Paris depicts the Judgment of Solomon. Both red and blue flashed and abraded glass are used, detailed with exquisite skill. (Photo by Michel Raguin)
The colored glass used in stained windows, also known as pot metal glass, is made by adding metal oxides to molten glass during manufacturing. Red (ruby) flashed glass was devised to lighten the value in the dark reds available in 13th-century leaded glass construction. Flashed glass is made by annealing a thin layer of colored glass on top of a layer of clear glass in the sheet production. This makes for a vibrant red and also makes it possible to render intricate shapes by abrading the colored surface layer to reveal the clear glass underneath. Blue and green flashed glass were later introduced and were popular in 16th century heraldic panels. By the 19th-century, acid etching replaced the laborious process of abrasion. Glass paint and silver stain (yellow) were often added to ‘flashed’ areas for additional detail work.
Silver stain can be seen (above) in the yellow diamond pattern and flag tassel. Silver nitrate is applied and fired to glass where the red flash layer has been removed, changing the treated area to a rich yellow. This allows for further image manipulation; when combined with red flashed glass, 3 colors (white/clear, yellow and red) can be permanently rendered on one piece of glass, reducing complicated cutting and leading of individual pieces of glass. Vitreous paint is the brownish color that is both solid line and tone and adds an additional dimension. It’s a mixture of ground glass, iron oxide and gum arabic, applied to the surface of the glass, then fired in a kiln for permanent adhesion.
Techniques and approaches changed over the time. While it’s not possible to chronicle hundreds of years of stained glass history in this post, some changes are reflected in this panel depicting St. Eustache. In the 17th-century, for example, new colors in vitreous enamel pigments were introduced, and often used in small-scale panels in domestic settings. Artistic styles in glass kept pace with the changes in other media, for example, introducing more three-dimensional modeling. Artists also began copying paintings onto glass. The strong lead lines were abandoned as painting techniques could be used as the primary design and pictorial elements. Renewed 19th-century interest in arts and crafts and, in Germany, a particular reverence for the late Gothic period and for Dürer likely inspired panels like this one.
Finding this small, skillfully painted panel in our Collections presents an opportunity to review these historic techniques, while pondering images of saints, their connections to the Gothic revival period, hunting lore and a popular German beverage. More on the beverage from Kathleen in part 2, and other collection objects from Sarah in part 3!
An account of the process of medieval stained glass construction by the 12th-century monk Theophilus can be found in:
Explore the 15th century windows of York Cathedral with the York Minster Stained Glass Navigator
Stained glass history:
Religious and Architectural Arts: