Frankly, when you have several types of labels on the shelf it may hard to tell them apart. Sometimes, it is simply the process of elimination:
• Paper, of course, is much cheaper and will easily tear, but plastics generally will not rip unless they are nicked or have special tamper evident qualities.
• The easiest plastic to recognize is vinyl. It has a distinct odor and makes you think of a shower curtain. It’s only natural to associate it with outdoor applications due to its moisture resistance and flexibility.
• EIM categorizes Polyester (aka Mylar)¹ by itself because its special qualities, but under the SPI coding system for recycling, it too, is classified as a plastic. Polyester / polyethylene terephthalate (PET) tends to be stronger, smoother and stiffer than other films and handles higher temperatures than vinyl or other synthetics. If you were to look at the adhesive side of a polyester label, you will typically see a shiny surface whereas other synthetics have a matte appearance.
Years ago, the label industry had to pretty much rely on paper, vinyl and polyester materials. When thermal transfer printing became the preferred technology for variable printing and barcodes, label converters like EIM started to ask for cheaper, smoother face stocks. Chemists went to work looking at the various features of plastics and came up with a wide selection of synthetic label options. (NOTE: Since thermal transfer printers use lower heat settings to transfer printed images, they can also accept a wider range of label adhesives, making the choices for plastic label stocks really extensive.)
So how can you quickly determine what the material is made of? You know what applications various materials work in, but you find it hard to tell them apart? Try these simple kitchen sink tests to give you a good clue:
|Water Test||Stretch by Hand||Application|
|Polyester (PET)||Sinks||Hard||Strong, excellent print quality, chemical and temperature resistance|
|Polyethylene (PE)||Floats||Easy||Lightweight, flexible, good abrasion resistance, preferred for packaging|
|Polypropylene (PP)||Floats||Somewhat Difficult||Chemical & scratch resistant, strong, good wide service temperature|