Don’t press them with a flat iron.
First, make certain you are describing poster condition correctly. People sometimes say their posters are wrinkled when they mean curled. A wrinkled poster is one that might sustain damage prior to or after delivery. It is characterized by sharp bends or significant damage resulting from crushing. Curling is a temporary paper memory that is a natural byproduct of rolling posters to fit in a mailing tube. These are tips to loosen curls.
Relaxer: Carefully remove posters from shipping tube. Lay posters concave down on a large flat clean surface. Cover with protective paper. Stack books on top and leave overnight. The next day, with image facing you, the convex poster should slightly grip the wall to which you tack. A reverse roll speeds the process but increases the chance of damage. Do not attempt unless you are very gentle, work on one at a time, or have experience handling large sheets of paper properly. Posters may be slid into the top of a hanging DeuPair Frame. Gravity will loosen remaining curl over time.
Tight or loose: Tightness and length of time that paper is rolled up increases stubbornness of the curl. Expect loose curls with overnight shipping of one or two posters. Just as four or more days enduring various temperatures can cause a bad hair day, posters — especially when tube is at maximum capacity — can (temporarily) loose their straightness.
If posters were as small as letters, they could be shipped flat in standard FedEx envelopes. Since they are over two feet long, as many as possible are rolled into sturdy tubes. The maximum amount of tightly rolled unlaminated posters that fit in a tube is about 10; with lamination is about six; grommets quadruples thickness on the ends.
Flat Box: Our online shopping cart calculates tube capacity, triggering the flat box option. To eliminate shifting, flat posters within a plastic bag are secured to the inside of a reinforced corrugated box. Framed posters within flat boxes arrive curl-free.