How to Uncurl and Flatten a Rolled Poster or Map

Important Documents and Photos Can Be Conserved Using This Technique

Nov 4, 2009

Paper records such as birth certificates, maps, posters and photographs often get folded or rolled up for long periods of time. Here are directions for uncurling them.

When paper is not stored in the proper way, it can curl into a stiff and brittle and mold-infested mess. Because it “breathes” (gives off and receives moisture from its immediate environment), it can be manipulated in several ways to restore it to its original supple condition. One of these is known as controlled humidification.

A Test for Determining the Proper Treatment for a Paper Document

Humidification treatment is not appropriate for all paper materials. Objects with high intrinsic or artistic value, those with certain inks (such as birth certificates, marriage licenses, etc.) or those with oil paints, watercolors, charcoal, chalks or pastels should not be treated in this manner. Also, do not attempt this technique on papers that are glued together or on any kind of parchment, vellum or metallic paper.

To test a document, dip a sterile cotton swab such as a Q-Tip ® in distilled water and roll it over a clean blotter to remove excess water. Gently roll or dab the area of concern, such as ink on a handwritten birth certificate, with the swab and check for any traces of ink, paint, chalk or other soluble materials on the swab. Check with a paper conservator before proceeding if anything appears on the swab. A directory of conservators in the United States can be found here.

A Four-Step Procedure for Flattening a Rolled-Up Paper Document

Each of the four steps in the process – cleaning, humidifying, preparing the chamber and flattening – requires somewhat specialized equipment. This equipment can be made from readily available materials such as fabric, hardware and glass. Read the entire process and gather materials before starting.

Step One: Clean the Paper

This is a very important step, because any dirt or grime left on a document will probably melt into mud during the process. This will set even further into the fibers of the paper and ruin it. Sweep the surface of the map or poster or other document with a clean, soft natural fiber brush.

Remove any foreign objects such as staples, clips, brads, rubber bands and transparent tape that has hardened. This can be a difficult and tedious process at times. Using an archivist’s staple remover can be helpful. Art supply stores sell dry cleaning sponges that will do a good job of removing surface grime if the paper is not too delicate.

Step Two: Assemble a Humidification Chamber

Assemble a humidification chamber using two containers. Both must be completely airtight and clean, and one must fit inside the other with plenty of room to spare. Decide whether a cool mist or a hot water vapor would be appropriate for the condition of the paper document. Generally, the cool mist requires more expensive equipment and is a gentler process.

The object of a hot water humidity chamber is to hold a quantity of water while supporting the papers without allowing them to come in contact with the water. First, pour about one to three inches of water into the larger tray/container. Place the smaller container or tray inside the bigger one to make sure the water won’t come near enough to splash inside it.

Step Three: Humidify the Paper

After this test, empty the larger container and replace the test water with at least one to three inches of hot tap water, approximately 110F to 140F. Gently lower the smaller container into the water, making sure the inside of the smaller tray stays completely dry. Then carefully place the folded or rolled-up paper into the smaller tray. Getting the paper wet may cause irreversible damage. Place a piece of waterproof material of some kind over the smaller container to protect the paper from condensation within the chamber, then place an airtight cover over the larger container.

Begin the treatment early in the day so that progress can be frequently monitored. Never leave objects in the humidification chamber overnight. In most cases, paper will begin to relax within four to six hours and will become supple enough to unroll. Check once every hour to ensure that the paper is not cockling or warping. Over-humidified papers will feel tacky to the touch and should be removed immediately.

Step Four: Flatten the Paper

The final step in this process is to flatten the folded or rolled document. The paper will be moist and weakened. Do not allow it to come in contact with water droplets. Place each document on a clean piece of blotting material (available at art supply stores) or wool felt and cover with another clean piece. Weight this sandwich of layers down with a smooth board or piece of heavy plate glass. Leave the paper under the weight overnight, or for several days if there is any evidence of cockling. Change the blotters several times during the process.

This entire process can be repeated if the paper did not completely unroll during the first attempt. Large maps, blueprints, posters and anything that has been tightly rolled may need several treatments and take several days.

Taking the curl out of fragile or acidic paper can be a challenge. Practice on a worthless document or two first, and never attempt this process on a valuable object.

The copyright of the article How to Uncurl and Flatten a Rolled Poster or Map in Antiques & Collectibles is owned by Marie Brannon. Permission to republish How to Uncurl and Flatten a Rolled Poster or Map in print or online must be granted by the author in writing.