Food Pouches That Stick Closed: Review Blocking Before the Filling Trial

A pouch that remains closed at the filling station gives the buyer an observation, not a diagnosis. Ask the co-packer to identify the first unsuccessful event: the gripper cannot pick up the bag, the mouth does not separate, or the zipper remains engaged. Keep a photograph or video reference linked to the pouch lot and the line recipe used.

For a useful supplier discussion, describe the surfaces involved. Does the resistance occur between the two inner faces, near a seal, or at the closure? Keep suspect pouches and an identified reference lot separate. A general complaint that the bags are sticky leaves both the material supplier and equipment owner without a reproducible comparison.

ASTM D3354-21 addresses existing adhesion between plastic-film layers. Its public scope specifically excludes predicting susceptibility to blocking. Temperature and pressure can affect the adhesion described by the method. Therefore, a report needs specimen and history information before it can inform this investigation.

Treat the report as one piece of evidence. It cannot, by itself, certify a finished pouch for the buyer’s particular opening sequence. Also keep it separate from a film coefficient-of-friction review: sliding behavior and separation of contacting layers are different procurement questions.

The following is an original buyer worksheet, not a laboratory procedure or a set of acceptance limits. Ask each responsible party to complete its part before comparing the suspect lot with the reference.

Have the co-packer record the equipment configuration and changes during the trial. If the pouch lot and operating setup both change, retain that fact in the result instead of attributing an improvement to the material alone. Ask the equipment provider to direct machine adjustments; a packaging evidence sheet is not a substitute for its operating instructions.

For example, an identified reference pouch might open under the recorded setup while a suspect lot does not. That narrows the next investigation, but it does not prove a chemical cause or establish performance at another speed. Record sample identity and the observed outcome before agreeing the next comparison.

An approval record should say which pouch revision, lot and trial conditions it covers. Keep unresolved storage history or an unmatched film specimen visible. Do not replace those gaps with a universal blocking limit, storage temperature or line-output promise.

Use the incoming pouch inspection guide for the wider receipt and release decision. This article addresses the narrower evidence link between contacting film surfaces and an opening problem.

For custom food packaging, send the product application, bag format, dimensions, closure, quantity by SKU and identified filling setup. Add the suspect/reference sample references and state what you need the supplier to clarify about the proposed construction.

Ask about sample availability and the scope of specification review for the project. Specialized laboratory work, machine troubleshooting and acceptance criteria need explicit agreement with the responsible providers; explaining a test here does not make that service part of a packaging quotation.