Curl - What is curl?
A distortion of materials characterised as a lack of lay flat that causes the material to bend or curve into a spiral shape. Curl is most commonly seen in paper although it can occur in other materials, and can be caused by heat, pressure, moisture (or humidity), manufacturing flaws, or a combination of these factors.
In labelling, curl can cause labels to peel off their backing sheet during manufacturing, storage, and/or printing, can cause a label to become too distorted for successful application to a substrate, and can also result in labels peeling off a substrate after application (usually when a label is applied to a curved surface). It is important, therefore, that all of the materials used to produce pressure sensitive labels have a number of key characteristics that can help to prevent curl (e.g. good lay flat and dimensional stability, the correct moisture content, and good flexibility) and that labels are stored and handled correctly (for example, by making sure that labels are stored in stable environmental conditions, by keeping sheet labels on a flat surface, and by ensuring that roll labels are not wound too tightly around the core).