Curled papers? Flatten and Unroll those Historic Documents

A simple humidification chamber you can build

Rolled panoramic photos or folded documents can be frustrating to open. Brittle with age, they tend to crack and tear if any effort is made to open them without first “humidifying” them.

What collector hasn’t encountered a panoramic photo or some historic document that has been rolled or folded for so many years, it isn’t safe to open them up for viewing? Too often, an attempt is made resulting in torn or damaged edges. It doesn't need to end like that.

The reason most documents or photographs are reluctant to unroll or flatten is that the moisture in the paper has disappeared, leaving the item stiff. In order to unroll or flatten the document, moisture needs to be slowly and evenly reintroduced. The easiest—and safest—way to do this is by slowly “re-humidifying” the document. The idea is to introduce moisture without getting the document we. Whereas libraries and archives go to great expense to humidify records, it is quite simple to do in your home.

To make your humidity chamber, a visit to your local hardware or building store should provide all the parts you need: A large (66-quart) Rubbermaid or Sterlite tub with lid; a couple of small, shoebox-sized containers; large sponge and a sheet of egg crate lighting panel.

MAKING A HUMIDITY CHAMBER TO FLATTEN DOCUMENTS

To make your own humidity chamber, you will need to acquire a few items:

Large Rubbermaid or Sterlite tub with lid
2 shoebox-size plastic boxes
large sponge (car-washing size)
Egg crate (found in Home Depot / Lowes ceiling supplies)
Distilled water
Jig saw
2 pieces of 20” x 30” watercolor 140-lb cold press board (art supply stores have this)

When you have your materials rounded up (it cost me less than $50 for everything except for the jig saw—I already had that!), you are ready to begin construction. It took me about 10 minutes, including setting up sawhorses for cutting out the egg crate.

1. Begin with placing your large tub on top of the egg crate and use a marker to tightly trace the base.2. Use your jig saw to cut out the traced pattern (wear safety glasses—this step will spit up a lot of little bits of plastic).3. Place the two shoebox size containers inside the larger tub. These will form the base for the egg crate floor.

4. Soak your sponge with distilled water. It doesn’t need to be dripping wet, but does need to be saturated.5. Place the wet sponge between the two smaller boxes.6. Set the egg crate on top of the two boxes.

7. Place the documents you want to humidify on the egg crate, making sure they don’t touch each other.

8. Place the lid on top of the large tub. For an added seal, you can put a garbage bag on the tub to act like a gasket before fastening the lid. Keep the container out of the sun to reduce chances of condensation.It will take at least 24 hours to humidify the documents. 9. After 12 hours, check to see if the documents have begun to relax. If not, reseal for another 12 hours. Don’t leave the documents in the sealed container longer than 48 hours. Inks may run and/or mold begin to form.

10. When the documents feel as though they are relaxing, place one piece of the watercolor cold press board on a flat hard surface (choose a location that will remain undisturbed for several days). Unroll or open the items to be flattened and arrange on the art board in a way that none of the documents touch each other.11. Cover the documents with your other piece of cold press board. Place an array of weights (multiple Schiffer books work real well!) to cover the board. The watercolor cold press boards will serve as blotters to draw out the excess moisture.

12. Check the documents after 4-6 hours. If the cold press board feels damp, turn it over and use the other side. Better yet, if you have more than a couple of sheets, replace the first set with fresh, dry boards and recover with your weights. Leave the items alone for 1-2 days (depending on how humid it is in the room where you are working). When you uncover the items, they should feel as though they are at room temperature. If they feel cool to the touch, they are still to damp. Turn over your boards and repeat the drying process.

Once your documents or photos have been flattened, the key to them not curling is how you store them. The best method with panoramas is to matt and frame them immediately. If this is not possible, layering them with acid-free tissue and weighting is the next best scenario.

Documents are best stabilized when encapsulated, but this is usually not practical for large collections. Again, sleeving with acid free tissue and storing flat in acid-free folders will help the documents to retain their new, flat condition.