Guide to Pressure Sensitive Labeling
1. Pressure Sensitive Labels
The Pressure sensitive or PS labels we see on the products and cartons we use every day, every day consist of Face Stock and Adhesive. Depending on the adhesive used, they adhere to surfaces with moderate to light pressure. But the label we see is only part of the story. PS labels are constructed as a sandwich of several layers:
- Top Coat
- Face Stock
- Release Coat
1.1 - Liner
The liner is the backing paper that makes up the web of a roll of labels.
1.2 - Release Coat
The release coat is a coating applied to the top surface if the liner. The release coat is designed to resist the adhesive, allowing the face stock and adhesive to peel away from the liner.
1.3 - Adhesive
The adhesive is the glue that sticks the face stock to the product. There are a wide variety of adhesive formulations available. Adhesive selection is generally based on the application:
1.4 - Face Stock
Although the most common face stock material is paper, many other materials are used including plastic films, foils, fabrics and laminates.
1.5 - Top Coat
The top coat is a coating or lamination applied over the face stock, to provide physical protection from abrasion or to enhance some other property of the label. Top coats can be used to improve adhesion or legibility of secondary imprints, typically used for date or lot coding. Special UV sensitive varnishes or films can be used to assist with label on product detection, during the labeling process.
1.6 - Label Copy Positions
The orientation of the copy on a label is an important consideration when specifying and automatic labeling system. The roll form and copy position chart below provides a standardized way to describe the eight possible combinations. For automatic labeling applications, labels are typically wound out.
1.7 - Label Size
Label size is defined based on the label's orientation on the web.
1.8 - Web Length
A roll of labels consists of a sandwich of web and labels, rolled in a spiral around a core. The chart below describes the length of the web on a roll of known diameter, based on the thickness of the label/web sandwich.
2. Label Converting
The manufacture of pressure sensitive labels or label converting is a multi-step process. In some cases, all of the steps described below can be completed on a single production line. Other label converters may choose to split the process into two parts; printing and finishing. Label converting consists of:
- Web Guide
- Die Cutting
- Matrix Removal
- Web Splicing
Read the rest of the guide to pressure sensitive labeling.