The Art and Science of Map Conservation and Preservation

Samantha Cook, Summer Intern, Montana Historical Society Archives

Archivists are tasked with preserving and providing access to historically significant records to anyone and everyone. Sometimes those records are in such bad shape that preservation work is required to allow access to the objects. Conservation and preservation work is time-consuming and challenging because there is no single approach that works for every object. This map is an example of the trial and error process that often occurs and makes archival work so fun and challenging.

The Antonioli family has been involved in mining in the Philipsburg and Butte-Silver Bow County areas since the early 1900s. Between 1998 and 2003, William Antonioli, with permission from his two brothers Frank and Peter, along with other members of the family, donated records and 608 maps related to the Antonioli family’s work in various mines. The maps in this collection have been in need of preservation work for many years.  My summer internship has allowed me to be involved in this process.  I recently completed a survey and inventory of the map collection in preparation for conservation work on those maps requiring immediate care.

This map (below), entitled, Mill Drawing, was the most in need of urgent attention. The map was in pieces and therefore difficult to measure and re-roll.  A complete description for the inventory wasn’t even possible until I could begin the conservation work.  It was the worst piece in the collection and the first I prioritized for conservation.

Mill Drawing  #103 before conservation
 MHS Archives Collection MC 417. Antonioli Family Map Collection
Photo credit: Samantha Cook

When I moved the map to the conservation lab, I was not sure how to approach the work. Not only was the map in pieces and made from a delicate and fine paper, it was also covered in dirt, dried mold and other materials from being used in the mines (yuck!). The condition of the map made it barely legible. My first step was to clean the map using a soft-bristle paint brush and a small piece of a soot sponge.  After I had removed a majority of the surface dirt and grime from the front and back of the map, I went to my next step of attempting to mend the drawing.

Mill Drawing #103 during archival
 taping conservation process
Photo credit: Samantha Cook

Since this drawing was in so many pieces and had been rolled for the past 20 years, mending the map was no easy feat, and required various approaches. First, I attempted to put archival tape on the map, which was a failure; the minute I lifted my hand from pressing the tape down the drawing would curl and tear into pieces again.

Because the map kept rolling, State Archivist Jodie Foley and I determined that the map needed to be flattened. We put the map under blotter paper, placed two flat boards and four weights on top and left it for twenty-four hours. The next day when I removed the wood and weights, I realized they had not made any difference on the map. I decided to attempt to mend the drawing again using larger pieces of archival tape. This stabilized the map a little more, but it was still very unstable. I returned the map to the flattening position with the wood and weights and waited a week. 

Mill Drawing #103 map during heat-sensitive taping conservation process
Photo credit: Samantha Cook

After a week, I removed the weights and determined the archival tape was still not strong enough. We decided to try archival heat-sensitive tape. This process involved tearing strips of heat-sensitive tape and ironing it on to the backside of the map (left), much like an old fashioned patch. We hoped that it would adhere to the paper and mend the map correctly. 




This process successfully mended the drawing, making it ready for encapsulation with polyester film to truly preserve and protect the map for many years of future use.

Mill Drawing #103 map after conservation and encapsulation
Photo credit: Samantha Cook

As this essay attests, archival work is an art and a science, in which good old fashioned trial and error helps to stabilize damaged records so archivists can conserve and preserve them and provide access to everyone. 

Thank you to the Antonioli family for this generous donation!