Packaging Industry Terms

To help those unfamiliar with our industry, we've compiled the following glossary of common packaging terms.



3 side seal pouch

Any bag made which has been heat sealed on 3 edges.


An ink roller used to control the amount of ink transferred onto substrate during line screen printing. Anilox rollers are often referred to by the number of lines, or divots, on the roll. Higher line counts mean smaller divots, which transfer less ink onto the substrate.

Back seams

A seal in a bag which runs down the middle of the back, in machine direction. Many back seams such as fin seals and lap seals are made by form fill and seal machines.


Fin seals are created when the inside edges of the substrate are bonded, leaving the seam standing out from the package, such as on potato chip bags.


Lap seals  are made when two layers of substrate overlap, forming a bond with no material standing out from the package.

Bond Strength – Seal Strength

A lamination term referring to the integrity of a connection between 2 or 3 materials glued together. Also known as a “destruct bond” where the strength means the materials will break before the seam does.

Bottom seal

A bond between two layers of polyethylene made by a heated bar (element) which does not separate the bag from the roll. The placement of this seal is determined by the machine and printing direction. Bottom sealed bags are separated by a guillotine type knife which leaves one half inch of unsealed material at the bottom of the bag.


While most people use this term to refer to any thin, clear packing material, “Cellophane” is actually a specific material made from wood pulp.


Coefficient of Friction – Important in ensuring materials pass through machines smoothly. Often important in Form Fill and Seal machines, where material not traveling properly can indicate a lack of maintenance on the machine.


The paper core, with a diameter between 3 and 6 inches, on which bags or packaging material is wound during manufacture.

Crimp seal

A sealing process which uses scribed heating elements to bond substrates, such as the end seals of potato chip bags.


In lamination, the amount of time an adhesive between two substrate layers takes to stabilize and dry.


The machined rollers on which printing plates are mounted for use in a CMF printing press.


These small, black lines are usually made on the edge of the substrate, repeating throughout the length of the roll precisely in the same spot in relation to the printed design. Eyemarks are detected by a photocell on the machine, to indicate when a task is required. Eyemark placement must be consistent for processing machines to produce the best results.

Flavor and Aroma Barrier

The ability of a substrate material as a barrier to flavour and aromas, often linked to its Oxygen Transfer Rate (OTR).

Form Fill and Seal Machine

Machines usually purchased by food producers to facilitate product packaging by creating packages and filling them with product in one step.


FFS machines can be oriented either vertically (VFFS) or horizontally (HFFS). Vertical machines form and cut packages, to be filled with product dropped into the package before final sealing. Horizontal machines are used in cases where dropping a product vertically may cause damage (such as pastries, chocolate bars and cookies) and instead, the product is placed into the package horizontally.

Gas Flush

A procedure used in food packaging where gas is used during the packing process to evacuate oxygen and moisture before the package is sealed.

Gauge - Mil

Interchangeable terms referring to the thickness of a substrate material.


This can either refer to the amount of pressure used to place ink on a substrate – or, more commonly, the measurement of the overall area used to print a design on a substrate.


Or “LBS per thousand” – describes the weight of material used to make 1000 impressions on a given material.

Line printing - Spot printing

Image printing using a set of premixed inks for each colour required in the design. This is also referred to as screened print.

Line screen

A count used to describe the concentration of dots in an image over a specific area, such as DPI – Dots per Inch. A higher line screen count results in a higher quality image.

Lineal ft

Refers to the number of feet unwound from a roll of substrate, measured along the length of the unrolled material.

Machine Direction

Describes the direction a film travels through a machine during processing, often used to decide the direction an image is printed on the film, and where cuts and seals are to be made.


Outer Dimension, Inner Dimension- OD is often used to describe either the size of a roll’s core, or the size of the complete roll. ID commonly refers to the inside measurement of a package, either with or without the width of the seals included.


Oriented Polypropylene – A term used to describe polypropylene which is stretched in machine direction, creating properties desirable in certain food processing situations.


Biaxially Oriented Polypropylene – Material which has been stretched in both machine and transverse direction, creating properties desirable in certain food processing situations.


Cast Polypropylene – Inexpensive, un-stretched material with very limited barrier qualities, not often used for food packaging.


Oxygen Transfer Rate – Describes a material’s barrier abilities against oxygen. This is particularly important to food packaging, as oxygen can damage oil and far molecules, decreasing shelf life of a product.


Polyethylene, a low cost soft flexible material often used as an outer wrap. PE is also used as a sealant layer for laminates, due to its ability to create hermetic seals.


Any substrate made of polyester, without coatings

Pet – “Coated”

Polyester substrate coated with PVDC to increase the film’s resistance to oxygen and moisture.

Pet – “Met Pet”

Polyester substrate coated with aluminum on one site. In addition to oxygen and moisture barrier, this coating provides protection against ultraviolet (UV) light, which can damage oil or fat molecules. Met Pet is commonly used in food packaging.

Process printing

A type of printing used to create photograph quality images by combining four primary inks (Cyan, Magenta, Yellow and Black). Other industries refer to this as CMYK printing.


A printing term referring to the total distance of one printed impression. This measurement is commonly used to determine the size of printing cylinder required to print the image.

Roll flags

Flags are used to indicate a splice or an area of misprinted images on a roll. These tell processors where to take action to ensure smooth processing. Some of our machines will remove misprinted images from a roll, creating a splice and adding a flag.

Roll Geometry

The straightness of the edge of a roll of substrate is very important. Processing material through a machine can prove a challenge if the roll moves out of line with the machine feeds. Rolls not within proper specification may be rejected by customers, and credited to the customer’s account.

Shelf life

Refers most often to food products where the effective life of the product from the date of packaging is limited. Products beyond their effective date must be removed from inventory shelves because they are expected to be stale.

Side weld

A process used specifically on polyethylene bags where two substrates are bonded together and separated from the web at the same time by a tapered hot element commonly referred to as a knife.


The machined rollers on which printing plates are mounted for use specifically in our Uteco printing press, “Emma.”

Slitting / slitter

A machine used to divide single, large rolls of web into smaller rolls. This is achieved by passing the entire web across cutting knives as it is removed from the larger roll. The divided webs are then rolled onto new, smaller cores. The same process is used to remove excess web from printed output rolls.

Splice / Butt Splice

Rolls of printed product often contain joins where two rolls have been fused, or misprints have been removed. Our protocol limits the number of splices in a single roll as they can cause waste or slow down operations. Any splices in a roll should be flagged for easy identification.


Any base material (polyethylene, polypropylene or other) used to make a packaging product.


Stand Up Pouch, one of our more popular products.

Transverse Direction

Opposite of machine direction – 90 degrees to the direction a film travels through a machine during processing, often used to decide the direction an image is printed on the film, and where cuts and seals are to be made.


Substrate which is to be printed on must be treated on the printing side by the substrate supplier. The opposite side of the substrate is not printed.


Completed packaging material – “Web” is usually only used to describe packaging materials still on their roll, before first use.


Water Vapour Transfer Rate / Moisture Vapour Transfer Rate – Describes a material’s ability to repel vapour, which can damage the shelf life of certain products.