Adhesive Bleed - What is adhesive bleed?
The migration of an adhesive (especially a pressure sensitive adhesive) in a label construction as a result of cold flow. Cold flow is another term for creep, which is a type of material deformation that is defined as the tendency of a solid material to slowly move or deform under the influence of mechanical stress. Creep is a time-dependent deformation and accumulates as a result of long-term exposure to stress; the rate of creep is determined by the material’s properties, exposure time, exposure temperature, and the degree of stress that is applied to the material. Temperature is a particularly influential factor as virtually all materials will creep when approaching their melting point. This means that creep can occur at relatively low temperatures; for example, some plastics and metals (with low melting temperatures) will begin to creep at room temperature, while glacier flow is a result of creep in ice.
In labelling, creep can occur in any of the materials used to make labels, although it is particularly problematic when dealing with adhesives – where it is usually referred to as adhesive bleed or adhesive ooze. Adhesive bleed is most commonly caused by too much heat and/or pressure being applied and can occur at any point throughout the manufacturing and printing processes, during storage, or after a label has been applied to a substrate. It can cause blocking (surface to surface sticking between sheets or rolls of labels), deform or discolour adjacent layers, damage printers, and prevent a label from successfully adhering to a substrate.Go Back to Glossary