The backing material (or liner) for a label is usually coated with a silicon layer on the upper side (closest to the label stock adhesive) to allow the face stock to release from the backing as it is applied to the end product. The backing material choice may matter depending on whether you require clarity or visibility through the backing (such as when overprinting) or the strength needed for particular types of machine applicators.  

Backing materials come in 3 main types: glassine, kraft or synthetic film

Glassine Backing: This is a general purpose uncoated transparent backing paper that comes in a range of colors and weight variations (though usually white, yellow or a faint blue). Most popularly used for labels being overprinted as sensors can detect gaps between labels.

Kraft Backing: Kraft backing paper is coated on one side and is commonly used when extra stiffness is required.  Kraft comes in a variety of weights and colors and is popularly used for sheeted or A4 laser labels as it maintains good rigidity when fed through laser and ink-jet printers and copiers.

Synthetic Film Backing: (or clear backing) comes in either clear polyester (PET) or polypropylene (PP)   and is used when the backing needs to be clear and very strong for high speed applicators. 

95% of the applications that you will encounter will be Kraft liners in 40-50lb. configuration.

For more information about liners, contact Cobblestone Tag & Label today!

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