Why laminated sheets curl and how to keep them flat
Curl comes from unequal stress: one side is laminated and the other isn't, the top and bottom films are under different tension, or the base film and the paper move differently with humidity.
One-side lamination
- Nylon base film is popular for book covers and other one-side work. Nylon breathes, so it moves with the paper as humidity changes and curls less than PET or OPP.
- Reduce unwind tension. Film stretched hot shrinks as it cools and pulls the sheet into a curl.
- Use enough heat to bond, but no more. Then let sheets cool flat before you stack them.
- Keep stock acclimated. Paper straight from a cold, damp warehouse curls more.
Two-side and heavy encapsulation
Use the same film top and bottom and balance the tension. For heavy gauges (cards, menus), some makers offer mapped and matched rolls: top and bottom rolls are paired so their stresses cancel out.
Decurler and cooling
If your laminator has a decurl bar, adjust it a little at a time. Cooling the sheet on a flat path (chill rollers or a flat table) helps more than people expect.
Browse films
Filter for nylon films for one-side covers, or heavy encapsulation films.