Handling and Drying Methods
Large format, or oversize, materials are difficult to handle when wet. Large format materials include, but are not limited to, maps, posters, broadsides, blue- prints and architectural drawings, and works of art on paper. These materials are usually larger than 11-by-17 inches. They are printed on a variety of materials, including paper, Mylar, cloth, and coated stock. The combination of size and material creates difficulties carrying, separating, and physically han- dling them. Drying jobs that involve these materials must be performed by at least two people working together.
Large format materials can be found in map rooms, government document depositories, and sci- ence departments. Archives and historical societies that contain historical records and blueprints; art, art history, and popular cultural collections; and rec- ords centers often house large format materials. Some rare book and special collections may contain large format materials. Of course, large format materials are stored in architectural and engineering depart- ments and building maintenance offices.
These materials can be stored in a variety of ways:
• Flat in drawers or cabinets
• Rolled, stored on end, or on their sides
• Rolled on a pole and stored vertically or hor- izontally
• Folded in filing cabinets
• Hung in vertical cabinets
Large format materials may be in poor condition because of the type of paper or cloth, the age of the item, or excessive handling by the public and staff.
If there is a lack of storage space in the institu- tion, large format materials may be relegated to base- ments, storage closets, or attics. These collections should have been identified during the prioritiza- tion phase and ranked for recovery.
Removing Large Format Materials from the Building or Water-Damaged Area Wet large format materials should be handled by teams of two.
• Remove water from any drawers or cabinets before moving the materials.
• Place a sheet of Mylar, Remay (a polyester spun cloth), or plastic over the top of mate- rials before moving them. Covering these materials protects them from dirt and soot as well as prevents loss of items and accidental damage during transport.
• If necessary, move and freeze items in the drawers. Cover the drawer with Remay or Mylar to prevent loss or damage.
• Covered material may remain in place in the vacuum freeze-drying chamber.
• If air drying, remove items from the drawers (use procedures listed below) and dry flat under white blotter paper and weights.
• Check with a conservator before handling or drying works of art on paper.
Removing Large Format Materials from Drawers
All these procedures require at least two people working together.
File Folders in Drawers
• Remove by folder first. The folder may be so wet it requires additional support.
• Slip a sheet of Mylar larger than the folder under the folder and lift up.
• Place it flat on a table or a bread tray or any large, flat movable surface. Be careful not to tear wet items.
• Transport items to a vacuum freeze-drying cham- ber or a freezer to await drying.
Loose in Drawers
• Slip a sheet of Mylar larger than the materials into the drawer and under the materials.
• Lift up and place items flat on a table or bread tray.
• Transport items to a vacuum freeze-drying cham- ber or a freezer to await drying.
Separating Wet Large Format Materials To separate wet large format materials, use sheets of Mylar that are larger than the materials. Mylar is better than plastic sheeting because it provides additional support. If Mylar is unavailable, plastic sheeting or Remay can be used. Mylar items, such as maps and architectural blueprints, should be hung to dry, not separated with Mylar, plastic sheeting, or Remay.
Paper Items
• Place the Mylar on top of the item and lift up slowly. The static electricity in the Mylar makes the paper stick to it and allows you to lift it up.
Do not attempt to separate paper using your hands. The paper will tear.
• Place the item flat on blotter paper or Remay.
• Items should be dried face up.
Note: Some large format materials, such as art and posters, may have water-soluble inks, which will run when wet. Do not touch these materials with your hands. Place them face up on blotter paper or Remay. Contact a conservator to treat.
Mylar Items
• Mylar should separate if pulled apart slowly. Be careful, because Mylar can rip.
• Dry items flat or hang on monofilament with plastic clothespins.
• Do not allow Mylar to dry together; it may fuse permanently.
Linen or Cloth Items
• Use Mylar to separate.
• Cloth becomes very heavy and fragile when wet.
• The older the materials, the more fragile. Many colors will run when wet.
• Dry face up on white blotter paper or Remay.
Contact a conservator to treat.
Encapsulated Items
• Open each item along the seam or tape.
• Place the item face down.
• Remove the Mylar carefully; turn the item over onto blotter paper, so it is face up; and remove the other sheet of Mylar.
Supplies for Drying Large Format Materials
• White blotter paper or Remay
• Mylar sheets (40-by-60 inches) or plastic cut to size
• Monofilament
• Plastic clothespins
• Bread trays or flat drying racks that support each item
• Lots of flat surfaces for drying
Potential Problems
Large format materials, when wet, may be problems to dry. The following types of problems may exist.
Maps 11-by-17 Inches or Larger
• Maps are fragile when wet.
• They will shred if not supported.
• Use Mylar or Remay to lift and move or separate wet sheets.
• Dry maps flat under blotters or weights. Watch for colored inks—they may bleed when wet.
• If the maps are encapsulated in Mylar, remove the top sheet of encapsulation and dry; then, en- capsulate between new sheets of Mylar with new buffered sheets of paper or card stock for support.
• Contact a conservator if there is a large quantity of wet maps.
Posters
• Posters are often backed or mounted.
• If the posters are encapsulated in Mylar, remove the top sheet of encapsulation and dry.
• Encapsulate between new sheets of Mylar with new buffered sheets of paper or card stock for support.
• If the posters are colored, contact a conservator for advice about drying processes.
Blueprints, Architectural Drawings, and Engineering Prints
• Blueprints, usually printed on paper that is acidic by nature, are created using a diazo process.
• They become brittle with age.
• Blueprints are usually rolled and wrinkled.
• Poor storage conditions are not unusual.
• They shred when wet and are extremely fragile, so handle with care.
• Dry flat on white blotter paper or Remay.
• Treat only if there are no “exact” copies andthey have monetary or artifactual value.
Linen Tracings
• Linen tracings become sticky when wet.
• They may separate, if you are lucky.
• They lose their finish when exposed to water.
• Dry flat on white blotter paper or Remay.
Mylar Tracings
• Mylar tracings will stick together on contact when wet.
• They will stay wet for months if untreated.
• If left wet and under pressure for long enough, approximately six months, Mylar tracings will stick together permanently.
• Separating stuck sheets may lift off printing.
• Dry flat or hang on monofilament with plastic clothespins.
• Do not fold. They will “learn” this position permanently.
If blueprints, architectural drawings, and engi- neering prints are available on microfilm, microfiche, or aperture card, then only small reproductions of originals remain, which microfilm reader/printers cannot enlarge to scale or original size. If patrons need to use blueprints, architectural drawings, or engineering prints in their original size, make the extra effort to treat the large format items.