Label Printing Glossary: 40 Terms Packaging Buyers Should Know

Quotations and technical specifications are full of terms that printers use daily and buyers meet occasionally. These are the ones that actually affect what you receive and what you pay.

Materials and construction

• Face stock. The printed top layer of a label. Paper or film.
• Liner. The backing carrying the labels until application. Also called release liner or backing paper.
• Laminate. The complete sandwich of face stock, adhesive and liner as supplied to the press.
• BOPP. Biaxially oriented polypropylene. A tough, moisture resistant film and the most common label film.
• PET. Polyester film. The most durable common face material, used where heat or solvent resistance matters.
• PE. Polyethylene film. Softer and more flexible, used on squeezable containers.
• Metallised film. Film with a thin vapour deposited metal layer giving a reflective finish at lower cost than foil.
• Substrate. Any material being printed on. Used interchangeably with face stock in most conversations.

Adhesives

• Permanent adhesive. Bonds without a clean removal path.
• Removable adhesive. Peels cleanly within an intended window.
• Wash off adhesive. Releases in caustic solution so containers can be recycled or refilled.
• High tack. Aggressive adhesive for low surface energy, textured or difficult substrates.
• Freezer grade. Formulated to bond at low application temperatures.
• Tack. Initial grab strength when the label first contacts the surface.
• Surface energy. How readily a surface accepts adhesive. Glass and PET are high. Polyethylene and polypropylene are low and need high tack adhesives.
• Migration. Product components moving through the face material over time and attacking the adhesive.

Printing processes

• Flexography. Printing from a flexible relief plate, one plate per colour. Low cost per unit on long runs, with a plate setup cost.
• Digital printing. Plateless printing straight from file. No setup cost, higher cost per unit, and every label can differ.
• Rotogravure. Printing from an engraved cylinder. Very high quality on very long runs, common in flexible packaging.
• Screen printing. Pushing ink through a mesh. Lays down a heavy ink film, used for tactile effects and opaque whites.
• Anilox. The engraved roller that meters ink to a flexo plate. Its cell volume controls how much ink is laid down.
• Plate. The image carrier in flexo. One per colour, and a real cost per artwork version.
• Registration. Alignment of colours relative to each other. Poor registration shows as fringing at the edges of type and images.
• Web. The continuous roll of material running through the press.
• Web width. The usable width of that roll. It determines how many labels sit across the press and directly affects efficiency.

Colour

• CMYK. Four process colours, cyan, magenta, yellow and black, combined to reproduce a wide range of colours.
• Spot colour. A specific pre mixed ink rather than a build from process colours. Used for brand colours that must be exact.
• Pantone. A standard colour matching system used to specify spot colours unambiguously.
• Extended gamut. Adding orange, green and violet to CMYK to hit more brand colours without separate spot inks, which cuts changeovers on multi SKU jobs.
• Opaque white. A heavy white ink laid under artwork on clear film so colours do not go transparent.
• Spectrophotometer. An instrument measuring colour numerically, used to control colour objectively rather than by eye.
• Delta E. The numeric measure of difference between two colours. A lower number means a closer match.

Finishing and converting

• Die cutting. Cutting the label to shape. A rotary die is a tooling cost per shape.
• Matrix. The waste web stripped away after die cutting, leaving labels on the liner.
• Varnish. A clear coating protecting the print. Available gloss, matt or tactile.
• Lamination. A clear film bonded over the print for heavier protection than varnish.
• Hot foil. Metallic foil applied with a heated die. High impact, and tooling is required.
• Cold foil. Foil applied in line using adhesive rather than heat. Cheaper for large foil areas.
• Embossing. Raising the substrate with a die to create a physical relief.
• Tactile varnish. A thick screen applied varnish giving a raised feel without embossing tooling.
• Slitting. Cutting the finished web into finished roll widths.
• Rewind direction. Which way labels face on the finished roll. Getting this wrong means the roll will not run on your applicator, so it is always specified on the order.

Application and quality

• Applicator. The machine placing labels onto containers.
• Dispensing. How cleanly labels separate from the liner at the peel plate on an applicator.
• Core diameter. The inner diameter of the roll core. Must match your applicator.
• Roll diameter. The finished outer diameter. Limited by what the applicator accepts.
• Labels per roll. Affects changeover frequency on the line.
• In line inspection. Camera systems checking every label during the run rather than sampling afterwards.
• Barcode verification. Grading barcode print quality against the ISO scale, rather than simply confirming a scan.
• Substrate proof. A proof printed on the actual production material, which is the only proof that shows true colour.

For how these decisions fit together on a real job, see the complete guide to label printing and our guide to choosing a label material.