Reference

Flexible Packaging Terms, Explained Plainly

Packaging quotes are written in a vocabulary nobody is taught. This is the working definition of every term you are likely to meet on a specification or a quotation from us, written for the person buying rather than the person manufacturing.

TermsAround 70, grouped by subject

CoversFormats, films, barrier, closures

WrittenFor buyers, not engineers

Based onThe ranges we actually run

Formats and Shapes

The shape of the pack, which decides how it stands, how it fills and how much of it a customer sees on a shelf. Each of these is a range we run.

Stand up pouch: A pouch with a folded gusset in the base that opens out so the pack stands unsupported when filled. The most common flexible format, and the default unless something argues against it. See stand up pouches.
Doypack: The original trade name for a stand up pouch, still used interchangeably with it.
Gusset: A fold in the film that opens out to add volume, either in the base of a stand up pouch or in the sides of a side gusset bag.
Flat bottom bag: Also called a box pouch or quad seal bag. Five printed panels and a flat base, so it stands squarely and stacks. Used where shelf presence matters. See flat bottom bags.
Side gusset bag: The traditional coffee bag shape, with folded gussets down both sides. Efficient on film and well suited to a degassing valve. See side gusset bags.
Three side seal: A flat pouch sealed on three edges, the fourth being the fold. Cheap, flat, and right for samples and single doses. See three side seal pouches.
Back seal pouch: Also called a pillow pouch. A tube of film sealed along the back and across each end, which is what most crisp packets are. See back seal pouches.
Spout pouch: A pouch with a moulded fitment and cap, so a liquid can be poured or drunk without decanting. See spout pouches.
Handled spout pouch: A large spouted pouch, typically five litres, with a carry handle die-cut through a reinforced seal. See handled spout pouches.
Custom shape pouch: A pouch die-cut to an outline other than a rectangle. Needs its own cutting tool. See custom shape pouches.
Drip coffee sachet: A single-serve sachet with a fold-out frame that hangs on a cup rim. See drip coffee sachets.
Roll stock: Printed film supplied on a reel rather than as finished pouches, for filling on your own form-fill-seal line. See printed roll film.
Sachet: Any small flat pouch, usually single dose.

Films, Structures and Materials

A flexible pack is almost never one material. It is a laminate: two to four films bonded together, each doing a job the others cannot.

Laminate: Two or more films bonded into one web. The outer layer takes the print, the inner layer makes the seal, and anything between them provides barrier or strength.
PET: Polyester. Stiff, clear, dimensionally stable and a good printing surface. Almost always the outer layer.
PE: Polyethylene. Soft, and it seals to itself at low temperature, which is why it is almost always the inner layer.
PP, CPP, BOPP: Polypropylene in its cast and biaxially oriented forms. Clearer and stiffer than PE, used where a crisper feel or higher heat resistance is wanted.
Nylon, PA: Polyamide. Tough and puncture-resistant, used where the product has sharp edges or the pack is handled hard.
Aluminium foil: A true barrier layer: effectively no oxygen, moisture or light passes it. Opaque to metal detectors, which matters on some filling lines. See foil pouches.
Metallised PET: PET with a microscopically thin aluminium coating. Most of the barrier of foil at lower cost and weight, and it passes metal detection.
Kraft paper: Unbleached paper used as an outer layer for its appearance and feel. It has no barrier of its own, so it is always lined. See kraft pouches.
Mono-material: A laminate built from a single polymer family, so the whole pack can be recycled together. See sustainability.
Micron: A thousandth of a millimetre, the unit film thickness is quoted in. Most pouches sit between 50 and 200 microns in total.
Micron gauge: The thickness of one layer, or of the finished laminate. A quote should state both.
PCR: Post-consumer recyclate: material recovered from used packaging and reprocessed into new film.
PLA: Polylactic acid, a plant-derived film used in compostable structures.
Solventless lamination: Bonding the layers with an adhesive that carries no solvent, so there is no solvent to retain and no odour to carry into the product.

Barrier, Shelf Life and Testing

Barrier is the reason a pack is a laminate rather than a bag. These are the terms a shelf-life calculation is written in.

Barrier: How well the pack resists the passage of oxygen, moisture, light and aroma. Always a matter of degree, never absolute except with foil.
OTR: Oxygen transmission rate: how much oxygen passes a square metre of film in a day. The lower the figure, the better the barrier. The number a shelf-life calculation starts from.
WVTR: Water vapour transmission rate, the same measurement for moisture. Decides whether a crisp product stays crisp.
Shelf life: How long the product stays acceptable in the pack. A property of the product and the pack together, never of the pack alone.
Aroma barrier: Resistance to volatile compounds passing in either direction. Relevant to coffee, tea, spices and anything stored beside them. See herbs and botanicals.
Degassing valve: A one-way valve that lets carbon dioxide out of freshly roasted coffee without letting oxygen in. See coffee bags.
Nitrogen flush: Displacing the air in the pack with nitrogen before sealing, so there is little oxygen left inside to begin with.
MAP: Modified atmosphere packaging: setting the gas mixture inside the pack deliberately rather than leaving it as air.
Seal integrity: Whether the seals actually hold. Tested by pressure or dye, and the check that matters most, because a perfect film with a bad seal is a failed pack.
Drop test: Dropping filled packs from a set height to confirm the seals and the film survive handling.

Closures and Features

Everything added to the pouch beyond the film itself. Each one has a cost and most have a consequence for how the pack runs.

Zipper: A reclosable profile welded inside the top of the pouch. The part the customer operates every day, so its quality is disproportionately visible.
Press-to-close: The standard zipper: two interlocking profiles pressed together. Available in heavier grades where reclosure matters more.
Slider zipper: A zipper with a plastic slider. Easier for a customer with limited grip, and more expensive.
Child-resistant zipper: A zipper needing a deliberate two-step action to open. Required for some products in some markets.
Tear notch: A small nick in the seal edge that starts a tear in a controlled place, so the pack opens straight.
Laser score: A shallow line lasered into the outer layer, giving a clean opening line without cutting the barrier.
Hang hole: A die-cut hole for peg display. A round hole or a euro slot, depending on the fixture.
Euro slot: The keyhole-shaped hang hole most European retail fixtures expect.
Window: A clear or unprinted area showing the product. It is the lowest-barrier part of the pack, so its size and position are a deliberate trade-off.
Spout and fitment: The moulded neck and cap on a liquid pouch. Specified by neck diameter and cap type.
Tamper evidence: A feature that visibly damages on first opening, so interference can be seen.
Valve: See degassing valve. On liquid pouches, a tap fitting rather than a gas valve.
Round corners: Die-cut corner radii, which stop sharp corners catching and tearing in transit.

Printing and Artwork

How the design gets onto the film, and the words your printer will use when something in the file is wrong. The full process is set out on the printing page.

Gravure: Printing from an engraved cylinder, one per colour. The standard for flexible film: dense, consistent ink and excellent repeatability across a long run.
Flexo: Printing from a raised photopolymer plate. Cheaper tooling than gravure, and mostly used on labels and simpler film work.
Digital: Printing with no tooling at all. Right for short runs and variable data, and the reason a small first order is possible.
Cylinder: The engraved roller carrying one colour. The main tooling cost, and it is held for repeat orders.
Dieline: The flat outline of the pack with fold and seal positions marked. Artwork is laid out on it, and it is the first thing we send.
Bleed: Artwork extended past the trim line so no unprinted edge appears if the cut shifts slightly.
Registration: How accurately the colours line up with one another. Poor registration shows as coloured fringes on type.
Spot colour: A specific ink mixed to a reference, usually Pantone, rather than built from process colours. The way to hold a brand colour exactly.
CMYK: Four-colour process printing, where colours are built from cyan, magenta, yellow and black.
Opaque white: A solid white ink laid down under the artwork on clear or metallised film, so colours read as intended rather than picking up the substrate.
Matt and gloss: The finish of the outer layer. Matt hides fingerprints, gloss lifts colour saturation.
Soft touch: A matt coating with a slightly rubbery feel, used on premium packs.
Vector artwork: Artwork built from shapes rather than pixels, so it stays sharp at any size. What an engraver needs.
Proof: A representation of the printed result for approval. A flat proof shows the artwork, a 3D proof shows the made-up pack, a press proof is printed on the actual film.

Commercial Terms

The vocabulary of the quotation itself. How an order actually runs is set out on the how to order page.

MOQ: Minimum order quantity: the smallest run that can be produced economically. Ours is 1,000 pieces per artwork.
Tooling: The cylinders and cutting dies made for your specific job. Paid once, held for repeats.
Lead time: The time from artwork approval to goods ready. Tooling, printing, lamination, converting and inspection each take part of it.
Pre-production sample: A sample made on the actual tooling and film before the full run is printed. The last point at which a change is cheap.
Stock sample: An existing unprinted pack sent so you can judge size, feel and construction.
EXW: Ex works: you take the goods at our factory and arrange everything from there.
FOB: Free on board: we deliver to the port and load; you carry the freight and everything after.
DDP: Delivered duty paid: we deliver to your door with duties settled. The simplest for a first order.
Artwork approval: Your written sign-off on the proof. Production starts from it, and it is the document a colour dispute is settled against.
Overs and unders: The small variance in delivered quantity that is inherent to a printed run. The tolerance is stated on the quotation.

Send Us the Brief

Tell us what goes in the pack, roughly how much of it, and where it is sold. That is enough for a specification and a price. Talk to the factory.

Frequently asked

Questions About Packaging Terminology

What is the difference between a doypack and a stand up pouch?

Nothing. Doypack was the original trade name and the two are used interchangeably.

What does 3 mil or 120 micron mean on a quote?

The thickness of the film. Micron is a thousandth of a millimetre and is what we quote in; a mil is a thousandth of an inch, about 25 microns. Most pouches fall between 50 and 200 microns.

Do I need foil or is metallised enough?

Metallised PET gives most of the barrier at lower cost and passes metal detection. Foil is the answer where oxygen must be excluded almost entirely, such as long-life coffee or milk powder.

What is a dieline and do I have to make one?

The flat outline of your pack with folds and seals marked. You do not have to make it: we send one for the format and size you choose, and your designer places the artwork on it.

Why does the quote mention cylinders?

Gravure printing needs one engraved cylinder per colour. It is the main tooling cost, it is paid once, and we hold the cylinders for repeat orders.

What is opaque white for?

A solid white layer printed under the artwork on clear or metallised film. Without it, colours pick up whatever is behind them and print weak or metallic.

What does OTR tell me?

How much oxygen crosses the film per square metre per day. It is the number a shelf-life calculation starts from, and the lower it is the longer the product holds.

Is a zipper the same as a resealable pack?

A zipper is the usual way to make a pack resealable, but it is not the seal that ships. We heat-seal above the zipper with a tear notch, so the pack arrives sealed and the zipper reseals it after opening.

What is the difference between EXW, FOB and DDP?

How far we deliver and who carries the risk. EXW is at our factory, FOB is loaded at the port, DDP is at your door with duties paid. DDP is simplest for a first order.

What is a pre-production sample?

A pack made on your actual tooling and film before the full run prints. It is the last point where a change costs little, so it is worth the few days it adds.