Treating a Civil War Map

In July, I’ve been treating a hand-drawn Civil War map from the Sam Houston Research Center in Liberty, TX.  The document was glued to a backing board with historical annotations describing Burr’s Ferry, a site where Texas anticipated that Union forces would attempt to enter from Louisiana.

The hand-written annotations on the backing board raise several perplexing issues about the map.  First, the annotations indicate that a battle took place at Burr’s Ferry in September 1863.  However, other historical resources indicate that while a Burr’s Ferry invasion was expected, it never actually materialized.  Of further interest, the map itself seems not to depict Burr’s Ferry at all; it shows a region about 80 miles to the southeast, near modern day Melville, LA.  Though informative in their own way, historical labels and descriptions can sometimes raise more questions than they answer.

The darkened, brittle map was spot-glued to its backing board.  Over time, it had fractured around the glued regions and large sections had been lost.  Subsequent caretakers had responded by applying tape extensively across the front of the map and enclosing the item in Mylar.  Accordingly, this treatment offered many opportunities for physical and aesthetic improvement.

The first priority was to remove the map from its acidic backing board, which was exacerbating discoloration and brittleness.  The first step toward this was to remove the tape.  Fortunately, the tape was commercial Filmoplast of relatively recent application, and it was able to be removed mechanically.

Tape Removal

Removing Filmoplast tape

The glue holding the map to the board was water-soluble, and likely animal-based.  Local humidification through a vapor membrane was partially successful, but proved too prone to leave board fibers attached to the map.  Greater success was achieved with direct application of deionized water in a fine, aerosol mist.  Very slow, careful work was necessary to avoid damaging the map and to minimize disturbance to the backing board.

Backing Board Removal

Removing map from backing board.

Next, the map was washed and deacidified to reduce brittleness and discoloration, and to add a pH buffer to guard against ongoing deterioration.  Because the map was severely fractured, I used a flat, controlled washing method called blotter washing that relies on capillary action to pull degradation components into thick, dampened paper.

Fractured Pieces

The brittle, fractured map required careful blotter washing to avoid further damage.

After drying, the map was lined with an opaque Japanese tissue to hold the pieces together and fill the losses.  The tissue was toned with diluted acrylic paint to approximate the color of the map after washing.  The variety of shades in the mottled paper necessitated simply aiming for a neutral middle color.  I adhered the lining to the map with a reversible, water soluble wheat starch paste, working on a light table to align the many tiny, fractured pieces.

Lining

Preparing the map for lining on the light table. Losses seen here will be filled with the toned Japanese tissue lining.

The archivists and I agree that it’s worth keeping the backing board with its puzzling annotations.  Next week, I will surface clean the board and apply a deacidification spray to help control future brittleness and breaking.  I will also create a mat to support the map and assist in future exhibition.  Now that the map is more secure and stable, perhaps a future researcher can shed additional light on this document.