This post comes from Laura Hashimoto and Bonnie Hodul, Rakow Library interns who are helping conserve the Whitefriars stained glass cartoon collection over the summer in conjunction with West Lake Conservators. Read more about this project and the collection in previous posts.
We were thrilled to discover that our summer internship coincided with the Rakow Research Library’s exhibition Revealing the Invisible: The History of Glass and the Microscope, which showcases the microscope and its evolving forms from the 17th to 20th centuries! In addition to going on a behind-the-scenes tour with one of the exhibition’s curators, we are fortunate enough to work among these fantastic objects each day. By bringing together rare books and archival material from the Rakow’s collection, didactics explaining innovative applications of glass in the scientific community, and displays of the various microscopes that have been created over the past few centuries, this exhibition really got us thinking about how these tools come into play in conservation.
As we open up a fraction of the approximately 1,800 Whitefriars rolls, we have come across a fantastic variety of materials, or “primary substrates.” The primary substrate is the material that holds the media on the surface of the drawing. We have seen beeswax-impregnated linen/cotton canvas, machine-made thick paper, kraft paper, tracing paper, photographic paper, and some unfamiliar substrates! The media on the surface of these materials has also been varied, and includes graphite, wax pencils, chalky materials, inks, and paints. These materials all hold important information about the Whitefriars’ stained glass window-making process. For example, many of these objects were used directly underneath stained glass, and needed to be robust enough to withstand this heavy manipulation. While the overall conservation treatment aims are the same for each type of substrate—surface cleaning, humidification, flattening, and tear mending/stabilization—these different materials and their interaction with the various media on the surface inform our treatment procedures.
Alongside the logistics detailed in our first blog post, where we looked at the BIG picture, we also need to focus on the tiny, microscopic picture to grasp a better understanding of the materials we encounter in conservation. Fortunately, Astrid van Giffen, associate conservator in the Museum’s glass conservation lab, let us make use of the lab’s Leica Wild M8 stereomicroscope!
Check out what we saw in the photomicrographs we took!
This black media is somewhat friable, meaning it is prone to being easily removed from the paper substrate. When we surface clean these kinds of objects, we are very careful not to disturb it, and clean only areas around the media!
This adhesive came off the plastic tape carrier and embedded itself in the paper substrate, which over time yellowed, darkened and stained!
These waxed canvases were featured in our last post, and were used and handled heavily in the stained glass window process. It was interesting to see how much the wax filled in the weave of the canvas fibers.
This object is made of a very soft, thin paper with quite a bit of structural damage.
This kraft paper is brown and rough, quite different from the other paper substrates we have seen.
This tracing paper is smooth, transparent, and very brittle, which means we need to handle it very carefully.
The tracing paper objects also have a number of these dark brown areas that resemble burns through the paper. They are part of the stained glass window-making process and how these tracing papers were used, but we are not sure about their exact origin, nature, or composition.
There is a green accretion on one of the tracing papers, which may be a corrosion product from a metallic inclusion (i.e. a metal oxide that has formed), although further analytical testing is required to confirm this.
This tear on a silver gelatin photograph shows the unique layers present in a photograph. The glossy top layer that holds the light and dark areas of the image is the photograph’s emulsion layer, which appears very different from the fibrous paper substrate support underneath it, seen here at the right edge of the top image at 6x magnification.
Microscopes and the microscopic world are integral to the field of conservation, and we certainly enjoyed bringing the two together for the Whitefriars’ stained glass window cartoon conservation project.
The Rakow Research Library is open to the public 9am to 5pm every day. We encourage everyone to explore our collections in person or online. If you have questions or need help with your research, please use our Ask a Glass Question service.