2025 Poster Session

In the late 18th century, Elias Prunner painted on a small canvas made of webs harvested from the Puster Valley of the Alps in what is now Austria. Gemalde auf Spinnengewebe or “Painting on cobweb” developed into a type of local folk art of predominantly ecclesiastical imagery; made to hang in windows while light shone through them. Social awareness of this style of painting doesn’t appear to have gone beyond the geographical limits of the Tyrol region until the mid-19th century when local art dealers found they could be sold as souvenirs to foreign travelers and employed multiple artists. The style changed from ecclesiastical themes to vignettes of local traditions and portraits of famous people. Since these paintings were made only for a short amount of time and by a small grouping of artists from a particular region, there are very few examples of them remaining, some estimates suggest ~100 or less.

A highlight of these paintings is in their materiality: that of the insect webbing that makes up the canvas, but as we discovered, not that of an arachnid.

The canvases were stretched and placed into a thick paper surround and then 'safely' packaged in either cloth-bound or paper-cover portfolios typically depicting a spider on a web just in case you forgot about the uniqueness of the object. Their material nature is inherently delicate and with the impacts of time, mechanical stress, and fluctuations in temperature and humidity, those that do remain are susceptible to future damage. Very few conservators have studied the material nature of these paintings, let alone treated them, and due to their rarity and fragility, it is necessary to inform the conservation community of their existence to avoid their potential passive extinction.

Northwestern University Libraries houses 5 of these paintings in various conditions, two having been treated in the 1980s. With sparse literature on the material nature of these objects, cross-disciplinary and international collaboration were necessary. Initial observations of these objects were compared to those in Manuela Wiesend’s 2012 thesis, which she generously supplied. Additionally, they were examined using Foster+Freeman’s VSC80 for reflected and transmitted light imaging, as well as stereo-microscopy to determine the layers and components of the painting. To further explore the materiality of the cobweb, polarized light microscopy was used to examine the fiber morphology, take measurements, and compare to reference samples of other insect-sourced fibers from the slide collection of the Art Institute of Chicago. From the analyses, it was clear that the webbing from the canvas has features that are distinctly different from other insect-sourced fibers such as arachnid silk and the far more common silkworm silk from wild or cultivated species.

Visuals on the poster will showcase the characteristics and features of these unique ‘cobweb’ objects: motifs on the original housings, subject matter, macro appearance, and patterns of damage. Images captured from the various analyses including imaging and fiber microscopy, and a brief overview of treatment techniques drawn from paper conservation will also be highlighted.