Rare book collectors often encounter maps, which present special challenges because they’ve usually been folded (and unfolded and refolded again) as part of their original use. They also make wonderful display pieces, so collectors may have to consider preservation and conservation for maps as hanging art.
Handling Antique Maps
When the oils and salts on your hands contact the paper, they can contribute to deterioration over time. Using white gloves is one option to avoid this, but wearing gloves also reduces your ability to feel what you’re handling–which can lead to tears and other issues. Most experts agree that freshly washed, thoroughly dried hands are preferable.
Always move old maps with caution; even the mount of a map can get brittle or split. Place a supportive, acid-free surface on your viewing space. That way you can lay the map on the surface and use the surface to move or tilt the map for viewing or other purposes. When you do pick up the map itself, use both hands to reduce the risk for bending, creasing, or tears.
Storing Your Rare Maps
Ideally all your maps will be stored flat, in either shallow drawers or acid-free boxes. Avoid stacking them on top of each other, as acid, mold, and other particulate can easily be transferred from one leaf to another. Each item should be stored in its own folder or mylar envelope. If a map is too large to be stored flat, it can be stored in a large-diameter tube made of acid-free paper or lined in mylar. Be sure to roll your maps parallel to the enter fold, rather than perpendicular. Place items inside a metal or wooden cabinet to protect the map’s edges from bumping.
Be sure to remove paper clips, binder clips, and post-its from your rare maps before storage. Metal corrodes over time, staining the paper underneath, while any acid-containing paper (such as a post-it) can cause ghosting on the paper underneath. If your item came with paperclips or other attachments, carefully document their location and other specifics before storing them separately.
Repairing Antique Maps
Because maps were (and are) frequently packaged with plenty of folds, maps are particularly susceptible to deterioration and tears along creases. While you may be able to complete very simple repairs at home, most should be handled by professionals. Misguided restoration efforts can drastically impact the value of your map. If your map has pencil marks or surface soil in the margins or on the verso, you can gently remove these with a soft eraser or with a dry cleaning pad and soft brush.
Like books, some antique maps have non-paper components. For instance, The Traveller’s and Tourist’s Guide through the United States and Canada has a wallet-style leather binding with gilt lettering. Talk to an experienced conservator about the best ways to care for leather and other materials without damaging the paper of your map.
Displaying Antiquarian Maps
Ultraviolet light triggers a chemical breakdown in paper. Avoid hanging antiquarian maps in direct sunlight; though glass provides some UV protection, it’s not sufficient to ensure that the document will not begin to break down. If an item is particularly precious, consider glazing the glass, which affords more UV protection. You can also rotate the locations of your hanging maps to prevent damage due to uneven light or temperature. Whenever you rotate your maps, take a few moments to examine each frame. Ensure that the bumpers and hanging mechanisms are still secure, and inspect the dust jacket.
As for mounting and framing itself, these processes are best left to professionals. They’ll be well versed in using archival materials, protecting both sides of your maps, and the perils of trimming a map’s margins. A knowledgeable dealer will happily offer you referrals to excellent framing professionals.