Flat Pouch & Sachet — Supplier Qualification Guide

What a Complete COA for Flat Pouches and Sachets Actually Contains #

Most COAs we receive from new laminate suppliers list basis weight and appearance. That’s it. For a flat pouch or sachet that needs to contain a food product, pharmaceutical powder, or cosmetic liquid through 12–18 months of shelf life, that level of documentation is functionally worthless.

A qualified laminate COA for pouch and sachet applications should include, at minimum: total laminate caliper (typical range 70–120 µm depending on structure), individual layer grammage for each substrate, OTR (oxygen transmission rate) in cc/m²/day/atm at 23°C and 0% RH, WVTR (water vapor transmission rate) in g/m²/24h at 38°C/90% RH, heat seal initiation temperature range, seal strength in N/15mm, bond strength between each laminated layer in N/15mm, and coefficient of friction (COF) for the outer and inner surfaces. Each value should reference the test method used — ISO 15105-1 or ASTM F1927 for OTR, ASTM F88 for seal strength, ASTM F2251 or ISO 8295 for COF.

When a supplier sends a COA that omits OTR or WVTR for a barrier laminate, our materials team flags it under what we internally track as a Category 2 documentation gap. Category 2 means: do not approve the lot until the missing data is supplied with a traceable test report. If they can’t provide it, that alone is a disqualifying signal.

One field almost universally missing from supplier COAs: inter-layer bond strength measured at each interface separately. A PET/adhesive/AL/adhesive/PE structure has two bond interfaces. We’ve had lots where the PET-to-foil bond measured 2.8 N/15mm but the foil-to-PE bond was only 1.4 N/15mm — well below the 2.0 N/15mm minimum we specify for food-grade sachets. The laminate passed overall appearance testing but would have delaminated in a hot-fill application within weeks.

The Parameters That Predict Pouch Failure Before It Reaches Your Consumer #

Four parameters predict the majority of field failures we see on flat pouches and sachets: seal integrity, barrier performance, bond strength, and COF. Here’s what the numbers need to look like.

Seal strength for a three-side-seal sachet in dry food or powder applications should be ≥25 N/15mm on all three seals, tested per ASTM F88 with a 15mm test strip width and 300mm/min crosshead speed. For liquid or paste applications with internal pressure, we specify ≥35 N/15mm. Below 25 N/15mm, the risk of seal failure during distribution increases significantly, particularly under ISTA 2A transit simulation conditions where repetitive compression and vibration apply cumulative stress to the seal perimeter.

OTR for a standard foil-barrier sachet (PET12/AL7/PE60 structure) should measure ≤0.05 cc/m²/day/atm. For metallized film structures without foil, OTR is typically 1–5 cc/m²/day/atm depending on metallization density — adequate for short-shelf-life snack sachets but not for oxygen-sensitive supplements or pharmaceutical powders. WVTR for a foil-laminate sachet should be ≤0.1 g/m²/24h at 38°C/90% RH.

COF matters more than most buyers budget for in their qualification process. An inner surface COF (sealant layer against sealant layer) that reads above 0.4 (kinetic) will cause jamming on high-speed form-fill-seal equipment running at 80–120 sachets/minute. We’ve seen COF values drift between supplier lots by as much as 0.08 units — enough to cause feed problems mid-production run. This is why COF must appear on every lot COA, not just the initial qualification batch.

The most commonly overlooked parameter in supplier qualification is bond strength at the foil-to-sealant interface specifically. Total delamination resistance looks fine in most COAs because the stronger PET-to-adhesive bond dominates the peel reading. Ask the supplier explicitly for layer-by-layer bond data. If they don’t run it, they can’t certify it.

Qualification Decision Logic — When to Approve, Conditionally Accept, or Walk Away #

The qualification decision for a flat pouch or sachet supplier isn’t binary. We use a three-tier framework that determines whether a supplier moves to approved, conditional, or disqualified status.

If all six parameters in our incoming protocol pass on the first submission lot, and the COA matches our documented specification sheet with no gaps, the supplier moves to approved status and subsequent lots are sampled at AQL 2.5 (per ISO 2859-1, inspection level II). That’s normal operating condition.

If one parameter is marginal — for example, bond strength at 1.8 N/15mm against a 2.0 minimum — but all other parameters pass, we enter a conditional approval: the supplier has 30 days to submit a root-cause analysis and two additional confirmed lots. No production orders ship on conditional material until the second lot confirms compliance. The cost delta of holding a lot for two weeks is small compared to a field delamination event.

If the COA is incomplete (missing OTR, WVTR, or interlayer bond data entirely), or if seal strength fails at any point on the first submission lot, the supplier is disqualified from the current project and placed on a hold list pending re-audit. We don’t offer a second sample run on the same formulation. A supplier that can’t run ASTM F88 on their outgoing lot doesn’t have the process control to supply food-contact sachets reliably.

One non-obvious recommendation: require that the COA test date falls within 60 days of shipment date for barrier-critical materials. Foil laminates don’t degrade in storage, but adhesive-cured laminates can experience continued crosslinking that changes COF and bond strength measurably over 90+ days. A COA dated six months before the lot ships is not a current lot certificate.

This logic applies cleanly to standard food, personal care and nutraceutical sachet applications. For pharmaceutical applications under EU GMP Annex 15 qualification requirements, the entire framework needs to be escalated to a full supplier audit with on-site verification — the document-only review described here is not sufficient for drug packaging.

Specification Notes for Brand Partners #

When you brief us on a flat pouch or sachet requirement, the most useful information you can give us upfront is: the product contents (food/non-food, wet/dry, oil-based or not), your target shelf life in months, your storage and distribution conditions (ambient, refrigerated, or tropical climate), and your fill equipment type (whether form-fill-seal, pre-made pouch fill-seal, or manual).

The gap we see most often in incoming briefs is missing shelf-life temperature data. A brand specifying 12-month shelf life without stating whether the product routes through Southeast Asian ambient warehouses (regularly 35–40°C) versus US climate-controlled DCs is giving us incomplete information. Barrier specification for a 12-month product in tropical distribution needs to be two to three times more conservative on WVTR than the same product in temperate conditions. This single omission causes more sample iterations than any other brief gap.

Our standard qualification sampling timeline for a new flat pouch or sachet laminate structure is 15–20 working days from approved spec sheet to physical sample with full COA. If your product requires a migration compliance test per EU No. 10/2011 (overall migration limit 10 mg/dm²) or FDA 21 CFR 177 food-contact review, add 20–30 working days for third-party lab testing before production qualification closes.

What fields are non-negotiable on a supplier COA for food-grade sachets?

OTR, WVTR, heat seal strength, interlayer bond strength at each laminate interface, COF (inner surface), and total caliper. A COA missing any of these for a food-contact barrier laminate is incomplete by definition. We will not approve a production lot on an incomplete COA.

Our fill equipment runs at 100 sachets/minute. What COF range should we specify?

For high-speed FFS equipment running above 80 sachets/minute, specify inner surface kinetic COF in the 0.15–0.30 range. Above 0.35, you’ll see feed hesitation. Below 0.12, you risk static buildup and film misalignment on the forming collar. These ranges hold for PE and CPP sealant layers — for matte-finish or specialty sealants, the range shifts, and we’d test before confirming.

What’s the difference between a supplier audit and a document review for qualification?

A document-only review (COA, test reports, food-contact compliance declarations) is adequate for standard food-grade and cosmetic sachet applications where the risk profile is moderate. For pharmaceutical packaging or any application governed by a regulatory body requiring supplier qualification (EU GMP, 21 CFR Part 211), an on-site audit covering equipment calibration records, process control documentation, and personnel qualifications is required. Our document review framework is not designed to substitute for a GMP audit.

If a laminate lot passes seal strength but fails COF, can we still use it?

It depends on your fill equipment speed and pouch size. For pouches filled manually or on slow equipment below 40 sachets/minute, a COF reading up to 0.45 may not cause production issues. On automated FFS lines above 80 sachets/minute, a COF above 0.38 in our experience causes measurable feed inconsistency within the first 500 sachets of a production run. We’d recommend rejecting the lot and requesting a reformulation, rather than adjusting equipment settings to compensate — equipment adjustments mask the material deviation and create a compliance gap in your process records.

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