Seal strength and leak integrity answer different questions. A seal-strength test measures resistance to separation; an integrity test looks for leakage paths. Before approving a food pouch, buyers should agree which risks need checking, which methods fit the package and what evidence will count as acceptance. A strong pull-test result alone is not a leak-test report.
For a purchasing team comparing pouch samples, the useful question is not simply “Did it pass?” It is “What was tested, under which conditions, and against which agreed requirement?”
What a seal-strength result tells you
ASTM F88/F88M-23 covers testing the force needed to separate a specimen containing a seal, including how the specimen fails. Its public summary explains that sample support can affect the result and identifies three techniques: A, B and C. Ask the laboratory to name the technique rather than comparing unexplained numbers.
As a buyer, request a report tied to an identifiable material, pouch version and production lot. Record specimen width, reported units and the seal location sampled. A result from a side seal should not quietly become evidence for every seal on the finished bag.
A real number—and its limits
The public scope of ASTM F2096-11(2019), an internal-pressurization bubble method, reports sensitivity down to 250 micrometres (0.010 inch), with an 81% detection probability. The same scope says sensitivity has not been evaluated for nonporous packaging or for porous materials other than spunbonded polyolefin.
That limitation matters when considering the method for a flexible food pouch. The figures are published method information, not a HEYI test result, a universal detection guarantee or a product defect rate. Ask the laboratory to establish suitability and sensitivity for your actual construction; do not copy the number into a purchase specification as a guaranteed capability.
Choose evidence for the question being asked
| Buyer’s question | Evidence to request | What it does not establish by itself |
|---|---|---|
| How resistant is the sampled seal to separation? | A seal-strength report with method and specimen details | Absence of leakage paths throughout the package |
| Does this package show leaks under the chosen conditions? | An appropriate integrity-test report with conditions and sensitivity | Performance under every distribution or storage condition |
| Will the supplied bag work on our filling line? | A documented trial using the intended bag and sealing process | Validation of unrelated bag sizes or future material changes |
Separate the supplier’s seals from your final closure
When a pouch arrives with an open filling edge, the final closure is made later. Define who owns that step and which samples represent it. Request separate identification of factory-made seals and customer-made closures in the approval record.
For resealable formats, also distinguish the zipper from a heat-sealed closure. Specify which part is being assessed rather than treating “closed bag” as a complete test description. HEYI’s custom stand-up pouch range includes zipper and window options; the selected format should be identified before agreeing the inspection plan.
Put a short acceptance plan in writing
Before requesting tests, agree the following with the supplier and, where needed, a qualified laboratory:
- Sample identity: bag drawing revision, material specification and lot reference.
- Test scope: which seal locations, package features and closure stages are included.
- Method: the agreed edition, preparation, conditioning and relevant test settings.
- Sampling: how specimens are selected and how results are recorded.
- Acceptance: project-specific limits, handling of failures and the decision-maker.
Do not invent a pass limit to fill an empty spreadsheet cell. If requirements are not established, use sample evaluation to develop them with the relevant technical team. Keep approval of the drawing, artwork and inspection criteria traceable to the same bag version.
Frequently asked questions
Does a high seal-strength value prove a pouch is leak-free?
No. Ask for evidence addressing leak integrity separately. Read the complete report, including sample identity, method and conditions, before accepting a broad performance claim.
Can two suppliers’ test numbers be compared directly?
Only after checking that the specimens, methods, units and conditions are comparable. Request the missing details first; a headline number is not enough for a fair purchasing decision.
Does a bubble-test result establish shelf life?
No. A result should be interpreted within the test’s stated scope. Shelf-life claims need a separate, product-specific assessment; this article supplies no shelf-life guarantee.
Discuss the bag and the inspection requirement together
Contact HEYI about your pouch project with the intended contents, bag drawing and any existing acceptance requirements. Include whether your team or a contract packer makes the final seal. For the commercial details to accompany that brief, use our packaging quotation checklist.
Sources checked November 8, 2026: ASTM F88/F88M-23 and ASTM F2096-11(2019), public scope and significance summaries linked above. This buyer’s guide does not replace the standards or a laboratory procedure.