From the moment a roll of sealing film comes off the production line to the time it's loaded for shipment, there's one essential step that can't be skipped — testing. It's not just a quick visual check on a few rolls; it's a systematic process of checking each item against standards, confirming they meet specifications before release. Leadtra Packaging conducts systematic performance verification on every batch before it leaves the factory.

Physical properties: Will it seal properly and open cleanly?

The two most basic indicators for sealing film are heat seal strength and peel force. Heat seal strength is measured according to GB/T 22638.7-2016 to verify that the fusion between the sealing film and the bottle mouth is secure. Peel force simulates the consumer's tearing experience and is controlled within a reasonable range to ensure a "tight seal, smooth tear."

Thickness and tensile properties also need to be tested. Uneven thickness can cause fluctuations in seal strength; insufficient tensile strength can cause the film to break on the production line. For food packaging laminates, there are clear testing methods for tensile strength, elongation at break, and other indicators.

Barrier properties: Keeping oxygen and moisture out

The core value of aluminum foil sealing film lies in its barrier properties. Oxygen Transmission Rate (OTR) and Water Vapor Transmission Rate (WVTR) are two key indicators. GB/T 19789-2021 specifies the differential pressure method for testing oxygen permeability of packaging materials. For aluminum foil used in food and pharmaceutical applications, oxygen and moisture permeability are required to be kept at low levels.

Hygiene and safety: The baseline for food and pharmaceutical use

If the sealing film is used for food or pharmaceutical packaging, it must also pass hygiene and safety tests. The GB 4806 series of standards sets strict limits on heavy metal migration, solvent residue, and overall migration for food contact materials. Test reports are the most direct evidence of material compliance.

Appearance and dimensions: The details you can see

Surface bubbles, scratches, wrinkles, and dimensional accuracy are all on the factory inspection checklist. Substandard appearance is grounds for immediate rejection, and excessive dimensional deviation can affect sealing precision.

Reference testing standards

Common industry testing standards for sealing film include: T/ZZB 1713-2023 "Plastic and aluminum foil composite sealing film for food packaging," covering technical requirements for PET/PE/aluminum foil laminates; GB/T 10004-2008 "Plastic laminated films and pouches for packaging," covering physical and chemical properties; and GB/T 3198-2019 "Aluminum foil for packaging," addressing the appearance, thickness, and barrier properties of aluminum foil substrates.

When it comes to sealing film testing, it's not about having the most tests — it's about testing everything that needs to be tested. If you have questions about testing standards or specific specifications, Leadtra Packaging can provide complete factory test reports and standard interpretations to help you confirm that every batch meets inspection requirements.