This summer we had the pleasure of hosting Emilie Duncan, who is now beginning her second year studying library and archives conservation at the Winterthur/University of Delaware Program in Art Conservation. As part of the program, students are required to complete two summer work projects in order to practice art conservation in a real world setting. Students frequently travel far afield to cultural institutions across the globe. Hagley was lucky to have the help of a student from just up the road.
We gave Emilie the task of examining some of the larger maps from our Published Collections Department. Examining a group of collection materials is called a conservation survey. This is a common practice among collecting institutions, so that budgeting, workplans and space planning can be determined. We wanted to get a better picture of the state of preservation of the group, and determine future conservation treatments. These maps have been rolled up for quite some time. In some cases there is a good reason for this; when flat they are too large to fit into any of the drawers in the library stacks. Finding storage for big stuff is a common dilemma in libraries and archives where architectural drawings, blueprints, panoramic photographs and even documents on parchment can extend to lengths beyond seven feet. Problems can occur when they are requested by researchers: sometimes they don’t fit on the reading room tables; sometimes pieces have broken off or are missing.
If they are requested by patrons off-site we have other difficulties. We can’t currently create a very useful digital surrogate, because these oversized maps are too big to fit on any of our scanners. Our current cameras don’t have enough pixels per inch to capture both the overall map and the tiny print. But these collections are worth visiting in person! There are so many interesting things to be found on these maps, many of which revealed changes in the Wilmington and Philadelphia region over the course 200+ years. For instance, I found the street where I live on one of the maps from the 19th century, and it shows the street had an altogether different name. Some regional or city maps have listings of various local tradespeople and merchants. These seem to function as the yellow pages of the age before the telephone. I imagine maps of these types hanging on the general store wall, where people might stop in to find the address of the local blacksmith, etc…
One problem with these maps is the breaks and tears in the paper that occurred with handling and rolling them, after they were weakened by long term display. Complications occur when these types of items need to be mended, because they have a layered structure. In order to hang the maps, the paper was lined (adhered overall) to a woven cloth and tacked on the top and bottom to wooden rods. The top rod would have had hanging rings and the bottom rod weighted the map, keeping it planar.
Map with distortions in paper, and loss, revealing fabric at left corner
Protection of the paper was achieved with a coat of varnish. This same varnishing for protective treatment was also used on globes of the time. Unfortunately, the varnish yellows on aging, and the more exposure to light it has, the darker it can get. Emilie also observed that heavier varnish layers had a tendency to form micro-cracks, which obscured the printing, because they caused diffusion of the light. This micro-cracking was exacerbated by the action of rolling.
Map with yellowed varnish and detached fragment
One interesting thing about yellowed varnish is that it fluoresces when viewed under ultraviolet light. Unaged varnish layers do not typically exhibit this behavior. It is something about the yellowing of the organic compound (changes in the chemical bonds in the molecule) that also allows it to fluoresce. We examined a couple of the varnished maps, using long-wave UV lamp between 320 and 400 nm. Below is an example of how one map appeared. This map’s varnish is a bright greenish-yellow under ultraviolet light. Blue areas of the image are merely a reflection of the violet colored light. Examining the color of fluorescence can aid in determining the type of varnish and the solvent that would be appropriate for its removal.
Map viewed under ultraviolet light
Thanks again to Emilie for recording her observations on the condition of the maps along with treatment recommendations. This information will be very useful for planning the preservation needs of this portion of the collection at Hagley.
Laura Wahl is the Library Conservator at Hagley.