By Stacey Kelly, Paper Conservator and Randy Silverman, Head, Preservation & Binding

In 2018, a Park City mining aficionado donated an oversized wall map to the College of Mines and Earth Sciences that documents the locations of mines in Park City in 1908. Because of the map’s deteriorated condition, Dean Darryl Butt contacted Marriott Library’s Preservation Department to ask if we would examine the piece. On examination, the map was backed with linen and had hanging rods mounted to the top and bottom to permit wall mounting. Due to the paper’s deteriorated condition, small bits of map broke away from the lining each time it was unrolled. It was agreed that Preservation would repair, stabilize, and permanently house the fragile original map in Marriott Library’s Special Collections, while providing digital reproductions of the map suitable for framing and reference to the College of Mines and Earth Sciences and the Park City Museum.

The 1908 Park City mining map is unique and historically important. It clearly pinpoints more than 100 sovereign mines situated in the mountainous Park City / Alta region and provides a clear sense of the high value of the numerous claims, with many overlapping at different depths. The image illustrates the significant role mineral extraction played in developing and settling the West, and demonstrates the massive scale on which this was carried out.

The map’s treatment began with the removal of the two hanging rods. The white fabric attached to the top edge was removed to reveal a strip of the map which had previously been hidden. The surface grime on the front of the object was then removed, resulting in a significant visual difference. The map’s various colorants were tested for solubility with a variety of solutions to ensure that no color or information would be lost during treatment. Temporary repairs were placed over extremely fragmented areas to provide support and the map was ready to undergo wet treatment.

Wet treatment of the map had to be completed in one day or risk the paper turning back into pulp. Once the linen backing was removed, the only thing holding all the fragments of the map together was the surface tension of water and the temporary support material. Because of the time constraint, substantial preparation had to be carried out in advance of treatment. Oversized tables in the lab were reconfigured to allow easy transfer and flipping of the extremely large work. All materials had to be precut to specific sizes and laid out for easy retrieval, along with backup materials in case something didn’t go according to plan. Because of the map’s large size and the time constraint imposed by the wet treatment, all of Preservation’s conservators and technicians pitched in to help during the lining treatment. The team even completed two practice linings on smaller works to get a feel for the process.

The treatment began with the object undergoing humidification, while the wheat starch paste needed for the lining was prepared. Once humidified, the map was sprayed to saturation with deionized water followed by two rounds of Tek-wipe washing to allow the adhesive between the linen backing and the map to swell. The map, supported with a sheet of Mylar was flipped, and the linen backing removed from the verso in strips. Excess adhesive was absorbed and wiped off with cheesecloth. After removal of the linen backing the map was gently washed until the leeching of deterioration products was minimized. During the washing, all loose fragments of the map were realigned in their correct positions. Some targeted cleaning was also done using Gellan gel to reduce local stains. At this point, the map was ready to be relined.

The map’s large size required the lining be accomplished in three sections. During this process It was essential that no air bubbles or wrinkles were formed as these could cause the map to split during drying. The new Japanese paper lining was humidified, pasted up and placed on the back of the map. Once the lining was in place, the map was flipped and the overhanging sections of the lining paper were pasted to the table. This step allowed the map to dry under tension, ensuring it dried without undulating or wrinkling. The whole map was then covered and lightly weighted to decelerate the drying process. This whole wet treatment was accomplished in the span of 12 hours.

The map was left to dry tensioned to the table for six weeks. Once released, the excess Japanese paper lining was trimmed from the map and a custom protective storage folder was made using lightweight materials. The treatment was successful in improving the physical and chemical stability of the map. Some harmful degradation products were removed during the wet treatment that improved the overall strength and flexibility of the map. The new, chemically stable lining will allow the map to be safely handled, viewed, and stored as needed. This treatment was a notable accomplishment for the preservation team, requiring Preservation’s paper conservator, book conservator, three conservation technicians, and a conservation technician volunteer to work together closely to ensure its success.