01Bottom formats and what changes between them
Leon and Louis Doyen of Lyon, France, patented an early version. Their US patent 3,380,646 (French priority November 14, 1962, granted April 30, 1968) describes a plastic container whose bottom is "folded in" to form a W-section, and says its shape "enables it to stand upright."
Suppliers sell several bottom styles, named for how the bottom is folded and sealed. Ask which ones a supplier makes in your size:
- Round bottom (Doyen): the W-fold bottom gusset described above.
- K-seal and plow (corner) bottom: variations in how the bottom gusset is sealed or folded at the corners. Ask for a sample of each rather than trusting a drawing.
- Flat bottom or box pouch: side gussets plus a flat bottom panel, so the bag sits like a box. US patent 9,475,248 describes this style: "due to its flat bottom, the pouch is capable of standing upright." People also call it a flat bottom bag.
- Side gusset bag: gussets on the sides instead of the bottom. Ask whether the style you're quoted is meant to stand.
- Spouted pouch: a spout fitment sealed between the pouch walls, as in US patent 4,452,378, for liquids and pourable products.
Don't pick a bottom style from a chart: ask for a sample of two styles in your size, fill them with your real product at your real weight, and stand them on a shelf.
02Film structures and barrier
A laminated pouch is two or more films bonded together. The University of Bologna's packaging lab lists PET/PE, PET/PP and PP/PE as common duplex structures, with PE or cast PP as the inner heat seal layer and PET used "for printability, stiffness, and barrier."
| Structure | What to know |
|---|---|
| PET/PE or PET/PP | Two films, one bond; ask for each layer's thickness |
| PET/metallized film/PE | A metallized PET or BOPP middle layer adds oxygen and water vapor barrier without foil |
| PET/aluminum foil/PE (or PP) | Highest barrier to oxygen, water vapor, light and aroma; not recyclable in standard streams |
| Kraft paper/PE | The film adds moisture and grease barrier and heat sealability |
| PE with EVOH | EVOH sits inside a coextruded film; its barrier degrades significantly with moisture |
| All-PE (mono-material) | The route to a store drop-off claim; barrier layers may need testing |
Foil is not known for flex-crack resistance: once a foil laminate flexes, it can crack and pinhole and gas transmission rises, Packaging Strategies reported in 2017. ASTM F392 covers conditioning flexible barrier materials for flex durability, so ask for barrier numbers after flexing, not just on flat film. If your product is wet or heat processed, ask how the structure protects any EVOH layer.
Comparing foil or metallized bags for dry goods storage? Our mylar bags page covers that format.
03Barrier numbers: what to ask for
Sellers write "high barrier" and stop. Ask for numbers, the test method and the conditions:
- Oxygen transmission rate (OTR): ASTM D3985 (plastic film and sheeting, coulometric sensor) or ASTM F1927 (barrier materials at controlled relative humidity).
- Water vapor transmission rate (WVTR): ASTM F1249 (plastic film and sheeting, modulated infrared sensor). ASTM notes WVTR "can often be directly related to shelf life."
- Seal strength: ASTM F88, seal strength of flexible barrier materials.
ASTM calls OTR an important determinant of protection, but not the only one, and says these methods work as referee methods only when buyer and seller have agreed on sampling, test conditions and acceptance criteria. Agree on them in writing, then shelf test your product in the real pouch.
04Closures, valves and print
- Heat seal only: no reclose, for single-use packs.
- Press-to-close zipper or slider: reclosable. Ask where it sits relative to the tear notch.
- Tear notch: tears open by hand. Mark its position on the dieline.
- One-way degassing valve: for fresh-roasted coffee, which gives off CO2 "equivalent to as much as two or three times its volume," per valve patent US 6,468,332. The valve lets gas out so the bag doesn't bulge or tear, and keeps air out.
- Child-resistant zipper: products under the Poison Prevention Packaging Act need packaging that passes the child and adult panel tests in 16 CFR 1700.20. Ask for the test report.
Print comes three ways:
- Rotogravure: engraved, chrome-plated cylinders. One set usually lasts multiple runs, and Packaging South Asia's 2019 comparison says gravure cylinders work out cheaper when a design runs two or more times, though flexo plates cost less for the first run.
- Flexo: plates, which hold up for repeat runs only if sleeves are used and preserved well, per the same article.
- Digital: no plates or cylinders. One short-run pouch seller we read prints digitally with no plate or die fees.
Ask for the cylinder or plate charge as its own line, who owns and stores the cylinders, the unit price at two quantities, and the minimum per design. See what MOQ means.
05Food contact and retort pouches
No pouch is "FDA approved." The pouch is made of materials that comply with the 21 CFR sections for your food and use, and the supplier puts that in writing. The sections that come up:
- 21 CFR 174.5: general rules. Any substance used must be "of a purity suitable for its intended use."
- 21 CFR 177.1520: olefin polymers, covering PE and PP sealant layers. It sets extraction limits and restricts some resins to certain conditions of use, so fill and storage temperature matter.
- 21 CFR 177.1630: polyethylene phthalate polymers, covering PET films.
- 21 CFR 175.105: adhesives. Laminating adhesive must be separated from the food by a functional barrier or, depending on the food, stay within limits such as a trace amount at seams and laminate edges.
- Food Contact Notifications: FDA says an FCN "is only effective for the manufacturer or supplier identified in the notification." If a supplier cites one, ask whose it is.
A retort pouch is heat processed in a retort after filling and sealing. The US Army describes MRE retort pouches as "three layers of blended polymers and a foil layer that keeps water vapor, oxygen and light out." If you pack a low-acid food (pH above 4.6 and water activity above 0.85, per 21 CFR 113.3) in a hermetically sealed pouch, 21 CFR 108.35 requires registering with FDA within 10 days of starting, and filing a scheduled process for each product and container size within 60 days of registering and before you pack. Plan that with your co-packer before you order pouches.
06Recyclability claims
The EPA says plastic bags, wraps and films "cannot go in your household recycling bin" and points people to retail drop-off. How2Recycle's Store Drop-off label (US only) applies to "flexible polyethylene-based plastics," and a January 2024 GreenBlue report on the label said PE films with metallized, nylon, EVOH, PP, AlOx or SiOx layers need testing to qualify. The barrier layer decides it.
Under the FTC Green Guides, an unqualified "recyclable" needs recycling facilities available to at least 60% of consumers or communities where it's sold (16 CFR 260.12(b)(1)); below that, qualify the claim, and a component that significantly limits recycling makes it deceptive (260.12(d)). See our sustainable packaging page, and kraft paper for paper-faced pouches.
07When a pouch beats a box or a sachet
Choose a stand up pouch for dry goods, snacks, coffee or pourable products in multi-serve amounts that should stand and reclose. Choose a folding carton for rigid shelf presence, and sachets or stick packs for single servings.
08Before you sign off
- Get a plain, unprinted sample in your size and fill it before you pay for cylinders or plates.
- Compare structures on the same barrier numbers and test conditions, not on words like "high barrier."
- Run your own shelf test with your product in the real pouch at your real storage conditions.
- Matching the pack to the product is covered in the course's packaging lesson, "Build packaging that fits the product," in Product Sourcing Secrets.
09How to spec it with a supplier
Write the pouch up with a dieline so every quote prices the same thing. Our packaging manufacturer list shows packaging factories, and The Vault lists their contacts.
| No. | Field | What to write |
|---|---|---|
| 01 | Format | Bottom style (round, K-seal, plow, flat bottom) or side gusset, with dieline |
| 02 | Size | Width x height x gusset in mm, fill weight and fill volume of your product |
| 03 | Structure | Each layer in order, outside to inside, with thickness, and the adhesive or extrusion bond |
| 04 | Barrier | OTR and WVTR targets with ASTM method, temperature and humidity; after-flex data |
| 05 | Seals | Seal strength by ASTM F88; seal width; fill-and-drop test with your product |
| 06 | Closure | Zipper type and position, tear notch position, valve, spout or child-resistant feature with test report |
| 07 | Method, number of colors, CMYK or Pantone references, matte or gloss finish, window if any | |
| 08 | Food contact | Letter of guaranty naming the 21 CFR sections (and any FCN) for each layer, ink and adhesive |
| 09 | Recyclability | How2Recycle approval or test result behind any label you print |
| 10 | Packing | Pouches per carton, carton size and weight, rolls or premade pouches |
10FAQ
Q01What is a stand up pouch made of?
Commonly two or three laminated films: PET or PP outside, sometimes a metallized, foil or EVOH barrier, and a PE or cast PP sealant inside.
Q02What is the difference between a stand up pouch and a flat bottom bag?
A classic stand up pouch has a folded bottom gusset that spreads when filled. A flat bottom pouch adds side gussets and a flat bottom panel.
Q03What is a retort pouch?
A pouch that is filled, sealed and then heat processed in a retort, often a heat-resistant foil structure such as PET/Al/PP retort grade. Low-acid foods packed this way fall under FDA's rules in 21 CFR 108.35 and part 113.
Q04Are stand up pouches recyclable?
Foil laminates aren't recyclable in standard streams. All-PE pouches can qualify for How2Recycle's Store Drop-off label, with testing for some barrier layers.
Q05Are stand up pouches food safe?
They can be, if every layer, ink and adhesive complies with the relevant 21 CFR sections for your food and use. Ask for a letter of guaranty naming them.