Glossary of Terms

Technical terms are often used in the flexible packaging industry that, whilst critical for design and production, are not well known or understood by the general public.

Our glossary aims to bridge this gap and help get everyone on the same page when talking flexible packaging.

Use the tabs below to navigate the glossary:

BOPP (Biaxially-oriented Polypropylene)

Biaxially-oriented polypropylene (BOPP) is a type of synthetic polymer film made from stretched polypropylene (PP). Stretching the film makes it more transparent, resistant to moisture, and provides a great substrate for flexographic printing.

This film is commonly used in food packaging because it provides a clear “window” for consumers to view the product inside the package.

Bag Features

Refers to the style or functional features added to bags. This can include things like angle seals for bottom gusset bags, resealable zip closures, die cut handles or holes for hanging, tear notches for easy opening, see-through windows, and perforation for permeability or separation.

Barrier | Barrier Properties

A ‘barrier’ or ‘barrier properties’ refer to the ability of a material to prevent or control the passage of gasses, liquids, vapors, and aromatics to a desired extent. This means that the material can either block or retain these elements from escaping or entering a package.

Basis Weight (paper)

Paper basis weight is an industry standard for the “heaviness” of a paper product, based on its mass per unit area. The measurement standards can differ across regions. In North America, the weight of paper is typically represented as pounds (lb) per ream (500 sheets). In the printing and packaging industry, basis weight is often referred to as the paper’s weight, which should not be mistaken for its thickness or density.

Biodegradable (material)

Biodegradable materials refers to materials that can be broken down and decomposed by microorganisms such as bacteria, fungi, and algae into its base substances; like water and carbon dioxide. These materials are considered environmentally friendly because they do not contribute to the accumulation of waste and pollution in the environment. However, this group of materials may require specific conditions, such as elevated temperatures and moisture along with the presence of microorganisms, and extended timeframes to break down effectively. It is also important to note that some biodegradable materials might degrade into potentially harmful or toxic substances than can accumulate in an environment.

Biodegradable film

Biodegradable film is a type of biodegradable material used in the flexible packaging industry. In material standards certification; like the ASTM, CAN/BNQ, and the EU EN; biodegradation tests are part of the battery of tests to determine a material’s composability but should not be considered a consistent or meaningful claim outside of this context.

Bread Bags | Liquor Sleeves | Merchandise bags

Also known as Notion and Millinery bags, these bags have a pasted ‘pinch bottom’ closure, open mouth, and its sides can be flat or have gussets. Flat pinch bottom bags are generally not free standing, however, gusseted pinch bottom bags can be freestanding when the bottom is folded to accommodate the full width of the gusset.

 Caliper (paper)

Caliper is a widely used measurement of a paper’s thickness. In North America, caliper values can be expressed in micrometers (µm) or mil (1/1000 inch). Occasionally, it’s used to determine paper density, which is measured in grams per cubic centimeter (g/cm3), to eliminate the need to convert between different units of measurement.

 Carrier Bag

A bag provided by a retailer or outlet for carrying items purchased on premises.

Cast Polypropylene | CAPP | CPP

Cast Polypropylene (CAPP or CPP) is a type of polypropylene film that can be heat-sealed, making it suitable for use in retortable packaging. While it is not as rigid as OPP film, it can withstand higher temperatures than LDPE when used as a heat-seal layer.

Compostable (material)

Compostable materials are materials that biodegrades into non-toxic components in a given timeframe, with the assistance of heat, water, oxygen and microorganisms, nourishing the soil that it returns to. Compostable materials are biodegradable, however, not all biodegradable materials are compostable. This group of materials have to meet specific standards; set out by the ASTM, CAN/BNQ, EU EN, ISO, etc.; in order to be certified as compostable. Note that the priority of composability standards, like the ASTM’s D6400, is to safeguard the quality of compost, agnostic of the origin of the material.

Compostable film

Compostable film is a type of packaging material that decomposes in either home or industrial composting environments within a specific timeframe, adhering to strict toxicity standards and rigorous standards testing. Compostable films offer an environmentally friendly flexible packaging option as the products’ disposal at the end of its lifecycle (when done properly) can positively impacting compost quality, won’t contribute to the accumulation of waste in the environment and leaves no visually distinguishable or toxic residues.

Conversion (Flexible Packaging)

Flexible packaging conversion refers to the process of crafting structures, such as bags, from flexible films. Conversion ensures that a products’ packaging is tailored to possess the characteristics and functionalities that supports the item being packaged and its intended end use.

Die Cut

In packaging, a die cut refers to a process of cutting a specific shape or design out of a material using a specialized cutting tool called a die. In bags, die cutting is often used to create unique shapes or designs in the bag, such as a handle or a window for product visibility.

Die Lines

Die lines refer to the pre-made outlines or template of a particular shape or design that are used to cut or shape materials like flexible film into a specific form or size.

Flexible Film

Flexible film is a lightweight, bendable material made from various sources such as paper, synthetic polymers, foil, or a combination of these elements. It is designed to be easily manipulated and shaped for various applications.

Flexographic Printing

Flexographic printing is a fast method of printing that uses flexible rubber or photopolymer relief plates to create impression on a substrate.

The process involves transferring ink from an ink well or tank to a fountain roll and then onto an anilox roll, which has a textured surface that holds a specific amount of ink.

The ink is then evenly distributed onto the printing plate.

The substrate, which is the material being printed on, is then fed through the press between the printing plate and an impression cylinder, where the impression is transferred from the printing plate onto the substrate.

Finally, the printed material is cured.

Form-Fill-Seal (FFS)

Form fill and seal (FFS) is a mechanical packaging process that continuously or intermittently shapes, fills, and seals packages using roll stock material. The process can be set up either horizontally (Horizontal Form-Fill-Seal, HFFS) or vertically (Vertical Form-Fill-Seal, VFFS), depending on the items being packaged and / or machine configuration.

Grammage (paper)

Grammage, in the context of paper, refers to a measurement standard that indicates how much a paper product weighs based on its unit area. Simply put, grammage is another way to describe the weight of paper. Using the metric system, it is expressed as grams per square meter (g/m2, gsm, or g/sm).


The part of a bag that is folded back into itself and is able to expand once opened or filled. Side gussets are commonly used to increase the internal volume of a bag, while bottom gussets can be used help the bag stand upright. To measure the size of a gusset, you would measure the full open width from edge to edge.

High Density Polyethylene (HDPE)

Polyethylene with a density of 0.94 g/cm3 to 0.97 g/cm3. Known for its balance of stiffness, toughness, stress cracking resistance, and heat resistance.

Horizontal form fill and seal (HFFS)

Horizontal form, fill and seal is a packaging method where the products are dispensed horizontally, usually on a conveyer belt, wrapped in flexible film and sealed. This method is used primarily for single solid products.

IFS PACsecure

The IFS PACsecure Standard is a set of guidelines for evaluating the safety, quality, and compliance of packaging materials manufacturing and converting processes.

It helps businesses meet the increasing demand for transparency and traceability in the market, while also improving product integrity and efficiency.

The standard applies to the production, processing, or conversion of packaging components and materials for use in primary or secondary packaging of food, cosmetics, household, and personal care products.

By meeting these standards, businesses can demonstrate their commitment to producing safe and high-quality packaging materials that meet customer and regulatory requirements.

Visit for more details.

Impression (Flexographic printing)

In flexographic printing, an impression is created when ink is transferred from the printing plates onto the substrate (a continuous roll of film). The plates are mounted onto a cylinder that rotates and applies pressure onto the substrate, leaving behind the desired image or text. This transfer of ink is what creates the impression on the substrate.

In-line Press

In-line press refers to the relative position of the printing press in relation to the rest of the manufacturing process. This type of press is mechanically connected to other operations such as conversion, die-cutting, or handle attachment. An in-line press is typically positioned horizontally alongside other machines in the production line, which is why it’s called “in-line”.


Lamination refers to the process of creating a composite (or multi-layered) film by bonding two or more layers of material together. This can be achieved either by extrusion, adhesion, curing or melting. Laminates can vary from a basic foundational material combined with an adhesive layer to numerous layers of material, each possessing unique properties, bonded together.

Length (bags)

Bag length refers to the measurement of the finished bag from the top edge to the bottom edge, oriented with its opening at the top.

Linear Low Density Polyethylene (LLDPE)

Linear Low Density Polyethylene (LLDPE) is a linear copolymer, with shorter polymer branches, and a density between 0.91 g/cm3 and 0.955 g/cm3.

It is mainly used for its balanced combination of flexibility and stiffness, as well as its resistance to stress cracking, relatively higher tensile strength and puncture resistance compared to LDPE. LLDPE can be used to make thinner films but has lower gloss, and a narrower range for heat sealing.

Low Density Polyethylene (LDPE)

Low Density Polyethylene (LDPE) is a type of homopolymer with a density ranging from 0.92 g/cm3 to 0.94 g/cm3. It is primarily used in packaging for its flexibility and strong melting capabilities.

Mil (polymer film)

A unit of measurement of the thickness of polymer films. One mil is equal to one one-thousandth of an inch (1/1000 inch). Generally speaking, the higher a film’s mil gauge the more durable it is, but there are many other characteristics that may influence this; for example, the type of resins used, additives and extrusion method.

Metallized Film

Metallized film is a type of flexible film that has a thin layer of metal, usually aluminum, applied to one or both sides of the film.

When used in packaging it creates a shiny appearance and provides additional barrier properties to the film, such as improved oxygen and moisture resistance.

The metallized layer can also help to reflect light, making the product more visible and eye-catching on store shelves.


Polyamide, also known as Nylon, is a type of material that is commonly used to create strong and durable films.

The two main types of nylon used for films are nylon-66, which is hard to process and more heat resistant (but more expensive), and nylon-6, which is easier to process (and less expensive).

Both types of nylon have good barrier properties against oxygen and aromas, but are not very good at blocking water vapor.

Off-line Press

Off-line refers to the relative position of the printing press in relation to the rest of the manufacturing process.

An off-line press is not directly connected to other machines in the production line. Because of this, an off-line press can have broader capabilities and operating speeds, often outperforming their in-line counter parts. This makes it a popular choice for producing rollstock.

Oriented Polypropylene (OPP)

Oriented Polypropylene (OPP) is a film that is stiff and has high clarity but cannot be heat sealed.

It is typically combined with other films, such as LDPE, to make it heat sealable. Additionally, it can be coated with PVDC (polyvinylidene chloride) or metallized to enhance its barrier properties.

Polyethylene (PE)

Polyethylene (PE) is a type of synthetic polymer that is widely used for packaging applications.

It is available in various forms, such as high-density polyethylene (HDPE), low-density polyethylene (LDPE), linear low-density polyethylene (LLDPE), and metallocene polyethylene (mPE).

PE film is known for its versatility, durability, and cost-effectiveness, and is commonly used for applications ranging from food packaging to industrial wrapping.

Polyethylene Terephthalate (PET)

Polyethylene Terephthalate (PET) is a strong and durable type of synthetic polymer that’s able to withstand high temperatures.

Biaxially oriented PET film is commonly used in packaging laminates to enhance the strength, stiffness, and temperature resistance of the packaging.

PET film is often combined with other films to improve its barrier properties and enable heat sealability.

Polypropylene (PP)

Polypropylene is a type of synthetic polymer that has a relatively higher melting point than polyethylene (PE).

There are two types of PP films commonly used in packaging: cast PP (CAPP) and oriented PP (OPP).

Post-consumer Recycled (PCR) Paper

Post-consumer recycled paper refers to materials that have been used by end-users such as households, businesses, or institutions, and are then collected for repurposing.

In the packaging industry, the proportion of post-consumer recycled content in the overall composition of the paper is often indicated, for instance, “comprised of up to 40% PCR fiber”.


A pouch is a small bag that is typically made by sealing flat sheets along the edges. It’s similar to a sachet, but slightly larger in size.

Pound sizes (paper bags)

An industry standard for categorizing the size of bags, where the pound figure usually corresponds to the weight in pounds the bag can carry.

While the precise dimensions of paper bags can vary across these size categories, their volume should accommodate an equal weight of dry ingredients, like flour or sugar, to their pound size and have some room to fold the top over.

For example, a 4# SOS bag should be able to accommodate about 4 pounds of flour with some head room for folding.

Pre-Press Services

Pre-press services refer to a suite of services that take place from the creation of a print layout to the final print production run.

This includes the setting of die lines, adjusting parameters for color profiles, bleeding, trapping, registration, spot print, and overprint for images and text.

Pre-press services also involve creating a high-quality proof for review and approval and developing printing plates used in production runs.

Quality Check (QC)

Quality Check (QC) is a process that involves multiple steps throughout the production process, implemented to ensure that the final product meets the necessary standards and specifications.

QC involves inspecting and testing the product at various stages of production to identify any defects or issues that may impact the quality of the product. The goal of QC is to prevent defects from being passed down the production line or on to the customer, and to ensure that the product is safe and performs as expected.

Resealable zipper

A zipper, or resealable zip lock, refers to a built-in sealing mechanism, consisting of a protruding rib or fin that fits into a corresponding channel to create a secure closure. This zipper seal can be conveniently opened and closed multiple times for repeated use.

Retortable Packaging

Retortable packaging is a type of packaging typically used for ready-to-eat meals and other food products that need to be sterilized before being sold.

The packaging is usually made of layers of different materials that are bonded together to create a strong and durable container, able to withstand the high heat and pressure of the sterilization process without breaking or leaking.


Rollstock refers to flexible packaging material often in a predefined tube shape, folded flat, set and wound around a core.

Rollstock can be dispensed by pulling it from the core and feeding it through other machinery, usually FFS machines, winders or wrapping equipment.

Self Opening Sack | SOS Bag

An SOS bag is a square-bottom paper bag with side gussets and an open mouth that, when opened, can stand up on its own for easy filling.

Shrink Films

Shrink films are a type of synthetic polymer film that is stretched in one or more directions to increase its strength and clarity.

Unlike heat-set films, shrink films can shrink back to their original size when heated. There are different types of shrink films, including PVC, PET-G, and OPS shrink films, which are used in a variety of applications such as packaging, labeling, and product wrapping.

Stand-Up Pouch

A Stand-Up Pouch is a type of flexible packaging pouch that has a gusseted bottom portion, allowing it to stand upright on its own for easy display and use. This design provides a wider base for support and stability, making it a popular choice for a variety of products.


In the context of flexible packaging, a substrate refers to the base material onto which additional layers or coatings are added to create a functional packaging material. The substrate can be made of various materials and provides the initial surface for printing, lamination, and other processes involved in the production of flexible packaging.

Technical Specifications

Technical specifications refers to the detailed description of all the features, qualities, and technical procedures involved in the development of a product. In flexible packaging, this can include information on packaging materials, barrier properties, film composition, size, weight, certification standards, labeling requirements, inks, solvents, curing processes, sustainability, and tracking and tracing. These specifications are important for ensuring the quality, safety, and functionality of the packaging and the products they contain.

Technical Specifications

Technical specifications refers to the detailed description of all the features, qualities, and technical procedures involved in the development of a product.

In flexible packaging, this can include information on packaging materials, barrier properties, film composition, size, weight, certification standards, labeling requirements, inks, solvents, curing processes, sustainability, and tracking and tracing.

These specifications are important for ensuring the quality, safety, and functionality of the packaging and the products they contain.

Vertical form fill and seal (VFFS)

Vertical form, fill and seal is a packaging method where the products are dispensed vertically into a preformed flexible package, usually a tube, and sealed. This method is used primarily for granular products and liquids.

Width | Face

Width or face refers to the measurement of the finished bag from left to right, oriented with the bag’s opening at the top.

Wicket(ed) bags

A wicket is a metal or plastic hanger or wire to which stacks of bags can be attached, allowing the bags to be dispensed one at a time.

Wicketed bags refers to a stack of bags attached to a wicket, usually near the top of the bag, creating a stable hanging point. This method of packaging is commonly used in the food industry for items like bread, produce, or bulk goods.