The visible surface of a coffee pouch is not the whole package. Most high-barrier coffee bags combine multiple webs so that printability, protection and heat sealing can be optimized separately.
The correct question is not simply “kraft or foil?” It is “what is the complete layer order, what job does each layer perform, and what evidence supports the finished construction?”
The four functional zones
| Zone | Common direction | Primary job | Risk if poorly specified |
|---|---|---|---|
| Outer web | PET, BOPP or paper | Print carrier, handling surface, stiffness and visual finish | Scuffing, distortion, weak shelf stance or inconsistent color |
| Ink and coating | Reverse print, white ink, matte or gloss treatment | Protected graphics, opacity and controlled appearance | Low contrast, rub-off, blocked windows or unreadable codes |
| Adhesive and barrier | Adhesive plus VMPET, aluminum foil or coated film | Laminate bond and project-specific oxygen, moisture and light protection | Delamination, poor barrier or a report that does not match production |
| Inner sealant | PE or CPP | Food-contact surface and heat-seal behavior | Leakers, narrow sealing window or incompatibility with filling conditions |
Three common construction directions
Quote comparison: two suppliers offer pouches with a similar matte exterior, but one lists PET/VMPET/PE and the other PET/AL/PE. Ask each to identify the full outside-to-inside sequence, nominal thickness, sealant, print side, and evidence tied to that construction. Compare the reports under their stated conditions and ask whether they describe film, laminate, or finished pouches. Then review the proposed valve, zipper, and converting route on a filled sample. The visible surface cannot reveal adhesive, barrier layer, or sealant. If a component changes after approval, record whether the existing report and food-contact review still apply instead of treating the original quotation as generic coverage. List adhesive and tie layers only when they appear in supplied construction data, and keep each layer role tied to that specification.
PET / VMPET / PE
PET commonly carries reverse printing, VMPET provides the metallized barrier direction and PE provides the food-contact seal layer. This route can support many retail coffee projects, but the actual barrier depends on film grade, metallization, layer gauges, converting quality and test conditions.
PET / AL / PE
Aluminum foil creates a continuous metal layer and can be considered as a high-barrier PET/AL/PE direction. The project must still verify the exact report, foil gauge, converting route, flex exposure, valve installation and finished-pouch seals. “Foil” on a quotation should never stand in for a complete specification.
See the aluminum-foil coffee bag details for the actual range entry; the final layer stack and test scope remain project-specific.
Kraft / VMPET / PE
The paper layer creates the natural visible surface; it is not normally the primary coffee barrier. The metallized film and sealant inside the paper-facing structure provide the protective and sealing functions. Paper shade, fiber texture, printing and rub resistance should be approved on a physical reference. The kraft coffee bag range likewise needs its complete laminate confirmed.
Why food-contact documentation is construction-specific
For the United States, the regulatory status of the finished food-contact material depends on the status and intended conditions of use of its individual substances. A generic statement about “food-grade material” is not a substitute for reviewing the actual sealant, adhesive, inks and use conditions.
What to write into the purchase specification
- Layer sequence and nominal thickness direction
- Print side, ink system and surface finish
- Adhesive or lamination route and curing requirements
- Barrier layer and applicable OTR/WVTR report reference
- Food-contact sealant and intended conditions of use
- Valve, zipper, dimensions, seals and approved physical sample
This prevents a common purchasing failure: approving the appearance of one material while receiving a different complete laminate in mass production.
Layer-order handoff
Write the outside-to-inside layer order, nominal thickness, sealant, adhesive or tie layer, print surface, finish, valve or zipper additions, and the evidence attached to that exact construction. Keep a visual reference, but do not use its appearance to infer an unrecorded layer.
Record the result with the project reference.
In practice
Keep the layer names connected.
A material description is useful only when it identifies the construction being ordered.
Ask for an identifiable specification
Record the layer order, relevant thickness information, selected sealant and any closure or valve details in the approved brief. Ask the supplier to identify the reference behind supporting performance information. Avoid comparing a number copied from one report with a different laminate that merely looks similar.
Where a quotation uses a shortened material name, request enough detail to distinguish the proposed construction from alternatives. Keep the agreed reference in the purchase record rather than relying on a color photograph or a general term such as high barrier.
Review substitutions explicitly
A change can affect more than one part of the project. A different surface may alter print appearance; a different sealing layer may require the packing partner to review compatibility. Ask which previous approvals remain applicable and which need another trial.
Do not treat an unchanged bag size as proof that the rest of the package is unchanged. Keep the revised specification, supporting documents and sample identity together so the next order does not accidentally mix the material from one revision with artwork or features from another.
