Preserving the Collections

After treatment, detail, upper corner.

1788 map of Gravesend, Brooklyn, before treatment, recto.

Visitors to the Municipal Archives are often surprised to learn that the oldest records in the collection—dating back to the early 17th century—are in better condition than more recent materials. For example, manuscripts of the Dutch colonial settlers in New Amsterdam are perfectly legible, exhibiting only minor degradation due to age. The fact that they are written in the old Dutch language is really the only impediment to their usefulness for historical research.

The reason the older records are typically in good condition is due to how paper was manufactured. Prior to the early 19th century, most papers were composed of cotton or linen rag. And like cloth, with reasonable care, they can remain intact and in good condition for centuries. With the rise of the industrial revolution, paper-makers swapped rag for much cheaper and more abundant wood pulp, which is now known to become yellow and embrittled with age due to the presence of a substance found in wood called lignin. It is common to find that paper produced in the 17th century is far more stable than that produced in the early 20th century.

However, not all of the early records in the Municipal Archives are in good condition. Over the years, some items have suffered from environmental hazards such as poor handling and storage, exposure to temperature and humidity extremes, all of which lead to deterioration.  

Before treatment, detail showing the former house of Antonie Jansen van Salee.

Recently, I was asked to treat a map of Gravesend, Brooklyn dating from 1788. The map was most likely submitted as evidence in a land dispute court case with the neighboring town of New Utrecht. Both towns claimed title over a marshy area that was a favorite fishing spot. The dispute, which originated with the 1645 deed to Gravesend, dragged on for centuries and may have been the longest running court case in the United States. By the time the case ended in 1898 with the consolidation of New York, it had been running for over 200 years. Most notably, in 1789 the Town of Gravesend hired Aaron Burr (yes that Aaron Burr) to defend them in court.* Another historic note in the map are the drawings of Dutch farmhouses, including the former house of “Antonie Jansen van Salee,” one of the earliest Muslim landowners in America. Van Salee will be well known to anyone who has read Russell Shorto’s The Island at the Center of the World, and despite his controversial place in New Amsterdam history his granddaughter would marry an indentured servant from the Dutch town of De Bilt in Utrecht, who would eventually change the family name to Vanderbilt.

After treatment, detail. A morgen (morning) was a Dutch unit of measurement representing the amount of land that could be plowed in one morning.

The job of a conservator in the Municipal Archives is to ensure a long life span for materials in our care via both preventive and interventive treatment. Our work rarely extends to a full restoration of an object, but we often repair damage and perform treatments to stabilize and improve the general condition of collections. Generally, the goal is to ensure that the intellectual content of the item continues to be accessible and the artifactual value of the object remains intact. 

The first step in most treatment projects is to document the condition of the item and assess its physical condition. The conservator measures and photographs the item, determines composition insofar as possible, and depending on the treatment needed, tests the stability of inks and pigments. All of this information is noted in a condition and treatment report. Then, consulting with staff archivists and sometimes other conservators, we map a treatment plan.

Before treatment, right center detail.

In the case of the Gravesend map, it was apparent that previous conservation treatment had been performed at some point. The front of the map, a.k.a. the recto, had been “silked,” probably in the late 19th or early 20th century, when the practice was common. Silking a document involves applying a type of starch paste and adhering silk gauze over the surface of the paper. The gauze is more or less transparent and was intended as an added layer of protection for the document. Over time, however, dust and dirt had become embedded in the silk, obscuring the surface, and brush strokes, darkened over time, were also apparent where the paste was applied. Additional backing layers were added to the verso – the map had been given a linen backing over the top of an additional paper backing. Evidence of several mended tears was also present throughout the document.

After treatment, right center detail.

After photographing the map and making condition notes, I began by cleaning the surface with eraser crumbs and smoke sponges to gently remove as much dirt as possible. I then tested the solubility of the media to determine if it is stable in the presence of water and alcohol. If any movement of inks or pigments is observed during testing, the conservator must proceed with caution and adjust the treatment plan as necessary. The media tested stable, so I proceeded with a bath to facilitate removal of the silking as well as the old backing and repair materials.

The water and alcohol bath softened the old adhesives used for the silk gauze and backings, allowing them to be carefully lifted away. I adjusted the pH of the bath with calcium hydroxide to increase the alkalinity of the solution and help to remove degradation products in the paper.

During treatment, detail of writing on verso and watermark.

Once I removed the various support layers, writing on the back of the map that had been covered was suddenly revealed. The old repairs made to reunite torn pieces of the map lifted some of the ink on removal, but the writing is still clearly legible. Also now viewable is an elegant watermark with a crown and the initials “G R.”

Upon removing the old linings and repairs, the map separated into eight large pieces, with many losses along the left edge and bottom center in particular. I rejoined the pieces with Japanese tissue and wheat paste. Working on top of a light table made the laid lines of the paper easier to see and realign. Existing planar distortions from the previous treatment made the realignment particularly challenging.

Finally, I lined the unified map with a medium weight Japanese tissue on the verso to provide support. I filled areas of loss with a lightly toned Japanese tissue. After post-treatment documentation, I returned the map to storage in one of the large flat files along with other Gravesend maps in the Archives’ collections.

1788 map of Gravesend, Brooklyn, after treatment, recto.

The fine details and additional text revealed during this treatment made the process especially satisfying. Researchers viewing the map now have a less obstructed view of the drawing, the document is safer to handle, and the condition of the paper makes it accessible for hopefully hundreds more years.

Lindsey Hobbs is Head of Conservation and Preservation at the Municipal Archives


*Gravesend: The Home of Coney Island, Eric J. Lerardi