Unrolling materials
Unwrapping tightly rolled paper materials, which are often brittle, can cause tears and breaks. Moreover, materials that have been rolled for some time tend to want to return to their rolled configuration. Thus when rolled materials need to be flattened, it may be necessary to introduce humidity to relax the paper fibers. Before flattening, make sure there is adequate storage for large, flat items.
Humidity should not be introduced to heavily coated paper, parchment/vellum, and materials with highly soluble inks, pigments, or other colors that might be affected by a high level of moisture. Generally, the principle of concentrating humidity is to create a micro-environment that can be controlled. A humidification chamber can be fabricated from any reasonably air-tight, rust-proof container, including plastic trash containers of various sizes, a refrigerator, rigid plastic trays, or plastic sheets.
A trash container can be used for large rolled materials, such as maps or architectural drawings. A smaller plastic container is needed to contain the documents inside the larger container. To increase the circulation of moist air, the smaller container should have a few holes cut into the sides, close to the top. About 8 centimeters of water is placed in the bottom of the large container. Sheets of blotting paper are laid around the inside of the large container and in the water. The blotting paper will help moist air permeate the container. The small inner container should be left open, and the large container should be sealed tight.
When the paper is relaxed enough for safe opening, the rolls should be removed. The time taken to attain an appropriate level of relaxation varies according to the nature of the paper, with thin paper taking around half an hour and thick paper taking considerably longer. Paper has achieved the right level of humidity when it feels pliable and seems to open easily. When the paper has been removed, it should be handled very carefully to prevent tearing, then gently unrolled and laid onto a sheet of clean blotting paper. Another sheet of blotting paper is placed on top along with a rigid board and a weight. A number of documents can be piled up with layers of blotting paper separating them in a vertical pile.
About fifteen minutes later, the blotting sheets need to be exchanged for dry ones. If the room is very humid, direct an electric fan on the piles to reduce the chance of mold developing. When the documents are thoroughly dry, which can take up to two days, the documents should be placed into their folders and enclosures.
If a refrigerator is used as a humidification chamber for smaller documents, it should be unplugged, and the metal shelves removed and replaced with plastic grill shelving (egg-crate-shaped panels from light fixtures are ideal). A plastic container of water is next laid onto the bottom of the refrigerator with a screen on top to protect falling documents from complete immersion.
Smaller single documents can also be humidified with a rigid photographic tray. Rigid plastic grill material is placed on the inside of the tray with the corners supported by non-corrosive objects to lift the plastic "shelf" clear of the water. The document is placed on a piece of spun-bonded polyester web, such as Reeme or Hollitext, and the tray is covered with a sheet of Perspex or Plexiglass.
With all humidification methods, you should periodically check inside the containers and wipe away any condensation that may fall directly on the documents.
