Shrink wrapping systems have currently gained popularity in creating airtight packages especially in the food industry. The film is wrapped around package while it is warm and clings tightly to the pack when cooled. Chemically, the molecules of the plastic material are disorganized in the structure. When a pulling force is applied, these molecules are aligned and cause visible stretching. When cooling occurs, the molecules shrink back and the material clings to the package. Processes applied to achieve this include the tenter frame and the bubble process.