High Barrier Flexible Packaging Gelbo Flex Testing

High barrier flexible packaging plays a critical role in modern packaging systems where oxygen, moisture, light, and aroma protection directly determine product shelf life and safety. From food and pharmaceuticals to medical devices and daily chemicals, high barrier flexible packaging combines multilayer films, coatings, and laminations to deliver advanced barrier properties while maintaining flexibility and cost efficiency.

However, barrier performance does not rely solely on material selection. During filling, handling, transportation, and consumer use, packages experience repeated bending, twisting, and compression. These stresses can create microcracks or pinholes, significantly reducing barrier effectiveness. Understanding how to evaluate and control these risks remains essential for quality control and packaging development.

Gelbo Flex Testing, and Barrier Properties Evaluation

ASTM F392 defines a standardized Gelbo Flex Testing practice designed to condition flexible packaging materials before evaluating their barrier properties and mechanical performance. Rather than measuring gas or moisture transmission directly, ASTM F392 focuses on controlled flex conditioning, which simulates real-world mechanical stress.

This approach helps packaging professionals answer a key question:
How well does high barrier flexible packaging retain its barrier properties after repeated flexing?

By linking flex conditioning with subsequent barrier tests—such as oxygen transmission rate (OTR) or water vapor transmission rate (WVTR)—ASTM F392 strengthens confidence in packaging durability.

Why Flex Resistance Matters in High Barrier Flexible Packaging

High barrier flexible packaging often uses thin functional layers, such as aluminum foil, metallized films, or EVOH. These layers deliver excellent barrier performance but remain sensitive to mechanical damage.

Flex resistance testing supports:

• Identification of flex-formed pinhole failures

• Comparison of alternative film structures and laminations

• Optimization of material selection for demanding distribution environments

Without flex conditioning, barrier tests may overestimate real-world performance. ASTM F392 bridges this gap by adding realistic mechanical stress before evaluation.

How Gelbo Flex Conditioning Simulates Real Use

Gelbo Flex Testing applies a repetitive twisting and crushing motion to film specimens under standard atmospheric conditions. This motion reflects stresses encountered during packaging operations and logistics.

Key aspects of the flexing process include:

• A controlled frequency of approximately 45 cycles per minute

• Repeated twisting followed by horizontal motion

• Uniform stress distribution across the test specimen

The number and severity of cycles vary depending on the packaging structure and the performance goal of the evaluation.

Integrating ASTM F392 with Barrier and Mechanical Tests

ASTM F392 works as a preconditioning step, not a standalone performance test. After flexing, laboratories typically perform additional evaluations, including:

• Oxygen transmission rate testing

• Water vapor transmission rate testing

• Tensile or tear strength testing

By comparing flexed specimens with unflexed controls, quality teams can quantify how flexing impacts performance and identify acceptable limits for high barrier flexible packaging.

Supporting ASTM F392 Testing with the Right Equipment

Reliable Gelbo Flex conditioning requires stable motion control and repeatable cycles. The Cell Instruments GFT-01 Gelbo Flex Tester supports ASTM F392 by providing controlled flex action and consistent cycle execution, helping laboratories maintain reproducible test conditions.

When combined with barrier testing instruments, the GFT-01 enables packaging engineers to evaluate how material choices and structure designs perform under realistic mechanical stress.

Conclusion

High barrier flexible packaging delivers exceptional protection, but its performance depends on how well it withstands repeated flexing throughout its lifecycle. ASTM F392 and Gelbo Flex Testing offer a practical and standardized way to condition materials before evaluating barrier properties and durability.

By integrating ASTM F392 into packaging validation programs and using reliable equipment such as the Cell Instruments GFT-01, manufacturers and quality professionals can design stronger, more reliable high barrier flexible packaging that performs as intended from production to end use.