Stretch wrap and shrink wrap, two packaging materials that are commonly used but often confused. We find many folks will use the term “shrink wrap” when they’re actually referring to stretch wrap. Some confusion is understandable since, at first glance, they may seem somewhat similar (the fact they both start with the letter “S” probably doesn’t help either). While they may appear similar, they’re not interchangeable they’re made from different materials, applied in different ways and best suited for quite different applications.
Clear shrink film is typically made from cross-linked polyolefin resin and has a slightly stiff feel to it. Stretch film is made from polyethylene resin, often combined with additives to produce desirable characteristics like puncture resistance and surface tack. Polyethylene stretch film is much more flexible and elastic.
Shrink film and stretch film both rely on tension to contain & unitize goods. How that tension is created is the most recognizable difference between the two. With shrink film, tension is created through the application of heat. High heat literally causes the plastic molecules to shrink and shorten, pulling the film tight around the package. Stretch film requires no heat. It is manually or mechanically stretched (up to 300%) then wrapped around a load. The stretching process elongates the plastic molecules in the film like tiny springs. After being stretched the film wants to return to its original length. The tension created by the “film recovery” secures the load.
Stretch film is the most common method of securing items to pallets for shipment because it’s easy to apply, economical and effective. Shrink film is somewhat more difficult to apply (even basic shrink wrap applications require equipment for sealing and heat-shrinking). Shrink wrap has a very clean and professional appearance which makes it ideal for packaging things that face the consumer in a retail environment.
Have a new or existing packaging application that you’d like to discuss? We can work with you to test and develop effective stretch or shrink wrap solutions suited for your specific application. Give us a call at (800) 665-4040 or (905) 507-4040.