by Bob Brooke
Much of the time, the paper on which an old map has been printed shows signs of wear and aging. Anything printed on paper is subject to mishandling and improper storage, and old maps are no exception. Over time, paper can become stained, frayed or torn at outer edges and weakened at folds if it was originally a part of a book or an atlas.
From the 1700s to the early 1800s, printers engraved maps on handmade rag paper which had a strong fiber content as it's base. In the 19th century, at the height of the Industrial Revolution, publishers began using machine-made paper which was inexpensive and readily available and made from a wood pulp base. While the early rag paper had little or no acid in its content, the later wood pulp paper was extremely acidic. Over time that acidity made the paper brittle, stained and yellowed at the folds. This is probably the most important reason why the early engravings have survived in much better condition than their later machine-made counterparts. Offsetting is another common defect found on old maps. When this happens, the text or image from a previous page shows through onto it's neighbor in a book or atlas. In the early days of printing, the oils in the inks took a long time to dry and if the map or print wasn’t completely dry before being bound into a book or atlas, sections of printed matter could transfer onto the back of a following sheet when pressed against it in the bound volume.
Another reason why early maps, especially those before the 19th century, have survived is that their owners valued them far more than maps are today and often kept them in libraries and government institutions and only brought them out and displayed them on special occasions for important dignitaries, scholars, and visitors. A cardinal rule in map collecting is the less people handle a map, the better its chance of survival as even the cleanest hands have oils and body chemicals that can be transmitted to the paper with harming effects.
Early sea charts present a different problem because printers engraved them on rag paper or its equivalent, and often backed them with linen fabric. Sea captains subjected these charts to all the rigors of life at sea. Coffee, oil and water stains are common on old charts, as well as tears and abrasions due to mishandling by sailors in rough seas. Captains or their mates often folded and refolded them or rolled them tightly, when damp, to fit into sailor's lockers or sea bags which caused soiling and staining to sink even deeper into the paper surface.Conditions Plaguing Old Maps
One of the prime conditions plaguing old maps and charts is foxing, a type of mold that shows itself as a series of brown dots that appear on many old maps that have been stored in damp, humid attics or storerooms for a long time. Foxing is a fungal growth that grows on old paper and books if the relative humidity is greater than 65 percent over a prolonged period and can ultimately destroy the cellulose fiber in the paper if left untreated. Many early maps came out of books and atlases, which users stored in boxes or closets where the air was still. The mold spores in the air could then attack the paper particularly feeding on any acid inherent in the book and paper contents.
Just as mold spores can attack paper, so can worms or larva which eat their way through the paper causing small holes in a map's surface. Worm holes are more common on old sea charts where the chart has been exposed to the open damp atmospheric conditions at sea where the larva can breed.
During the 19th century, large wall maps of States, Counties and Towns, became popular for schools, town offices and for display in houses of the wealthy. Makers fitted them with poles at top and bottom and backed them with a linen fabric. They also shellacked them in what people considered at that time, a way to protect the surface of a map from damage due to touching and handling by schoolchildren and others tracing their streets and houses and land boundaries on the maps. Unfortunately, over time the shellac dried out and cracked, causing the map surfaces to lift from the backing which became torn and frayed. In many cases the poles fell out as the backing gave way and once their popularity waned, their owners rolled them and stored them in attics and closets, where their deterioration continued, attacked often by mold spores, worms and damp. Restoring these maps is extremely difficult as the old shellac has to be removed before any conservation work can be attempted.
Six Things to Avoid in Caring for Your Old Maps But there are some simple things to avoid when caring from your old maps:
There are things you can do to preserve your collection of old maps without resorting to major conservation methods, which can be costly and time-consuming. However, if a map has major tears or staining, you should take it to a professional paper conservator.
1. Never use ordinary Scotch or Magic Tape to repair even minor tears. Instead, use a product called "Document Repair Tape" which is an archival acid free mending tissue that’s thin but strong. It’s also non-yellowing, unlike Scotch Tape which yellows with age, and virtually disappears when burnished.2. Never use an ordinary eraser to remove soiling from the surface of old maps since erasing tends to lift the inks off the engraved surface. Instead, use a product called "Document Cleaning Pad," which is non-abrasive and contains a super soft grit-free powder that absorbs surface soil and finger prints.3.Never mount a map or print onto a backing board with an adhesive, as adhesives can destroy the delicate fibers in the paper and cause staining. It also causes loss of value in the map especially if the map is a rare or scarce item.
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