Lamination is the process of placing an item between layers of plastic, followed by binding them with heat or pressure. There are many reasons to laminate, including to protect the material, to improve appearance and to increase sales. Despite its benefits, laminating sheets tend to curl after the laminating process. Fortunately, there are ways to keep laminating sheets from curling so that they can still remain stable with a professional appearance.
Apply film through a wet laminating process instead of a thermal laminating process. A wet laminating process provides less stress on the film to prevent curling. This is because wet lamination doesn't expose the film to the heat used to apply a thermal film.
Avoid humidity and keep laminating sheets dry before and after lamination to prevent curling. Curling occurs when the unlaminated side of paper absorbs moisture and expands while the film laminated side remains stable.
Use a laminating machine that's equipped with an anti-curl device such as breaker bars. Be sure to adjust the breaker bars properly to help reduce curling.
Adjust the unwind tension. Two-sided lamination typically involves a stretch-induced curl. You can usually correct it by adjusting the unwind tension of either the top or bottom roll of the film, depending on whether the curl is upward or downward. To flatten the sheet with an upward curve, provide less unwind tension on the top of the roll. In contrast, flatten a downward sheet with less unwind tension on the bottom of the roll.