Choose thickness according to the handling level and flexibility the finished piece requires. Thinner film is practical for posters, notices, maps, and documents that need protection without becoming rigid. A medium thickness works well for frequently handled instructions, teaching materials, schedules, and reference sheets. Thicker film adds stiffness for reusable signs, cards, tags, and materials that need greater resistance to bending. Your laminator must support the selected thickness, as heavier film may require different heat and speed settings. Using a thickness outside the machine’s rating can lead to cloudy areas, weak adhesion, curling, or feeding problems. Standardizing a few approved thicknesses can also reduce ordering mistakes when several people purchase supplies.