If you’re in charge of QA for flexible packaging, you know the cost of a missed leak can be far more than just a defect—it’s a recall, a reputation hit, and a risk to consumer safety. In fact, the FDA has cited package seal integrity failures among the top reasons for food and pharma product recalls in the last decade. Whether you’re working in food processing, medical device packaging, or CPG, one wrong move in leak detector testing can compromise everything downstream.
This guide breaks down the five most common and expensive mistakes made during leak testing for flexible packaging—each one drawn from real industry oversights. More importantly, it shows you how to prevent them.
1. Using the Wrong ASTM Test Method
Each package type requires the right test—using the wrong method leads to inaccurate results and missed leaks.
There’s a reason ASTM developed multiple leak test methods for flexible packaging. Not every package type responds the same way to vacuum or pressure-based detection. Still, it’s common for teams to default to familiar standards like ASTM D3078 without considering whether it truly fits the product.
ASTM F2096, for example, uses internal pressurization to detect leaks and is ideal for vacuum-sealed products like meats or sterile medical device pouches. But if that same test is used on a package with generous headspace, the result might look fine when in reality, it’s anything but.
Compare Test Methods:
| Feature | ASTM F2096 | ASTM D3078 |
| Test Type | Positive Pressure | Bubble Emission (Vacuum) |
| Headspace Required | No | Yes |
| Leak Detection | Visual (bubbles) | Visual (bubbles) |
| Best For | Vacuum-sealed | Air-filled flexible packages |
If you’re testing without evaluating which ASTM method matches your package type, you’re gambling with accuracy. Every package demands a method that reflects its actual use conditions. Wrong test = wrong result. It’s that simple.
How to Fix It: Revisit your packaging specs before selecting a test. Is there headspace? Is it vacuum-sealed? Match that against the test’s design.
2. Inconsistent or Damaging Sample Prep
Poor handling and prep can create leaks that don’t exist—or hide ones that do.
Sample prep isn’t just a step. It’s a risk multiplier. Errors here can invalidate your leak detector results, regardless of how accurate your equipment might be. Some common prep oversights:
- Leaving residue on packages (water, oils) blocks true leak paths
- Skipping temperature conditioning creates pressure differentials
- Using too few or non-representative samples throws off statistical confidence
- Mishandling during setup causes damage that looks like a leak
How to avoid these errors:
- Always clean and dry the test area
- Condition samples to ambient temperature
- Randomize and rotate sample selection
- Handle using approved tools and techniques
Leak testing begins well before the detector powers on. Prep like the results depend on it—because they do.
3. Skipping Calibration and Maintenance
Uncalibrated equipment undermines your test data and puts compliance at risk.
You wouldn’t rely on a stopwatch that doesn’t keep time, yet many QA labs push leak detectors well past their calibration windows. When test data matters for compliance, customer specs, or recalls, it’s non-negotiable.
ASTM doesn’t always prescribe exact calibration intervals—instead, it defers to equipment manufacturers. Most recommend calibrating every 6 to 12 months, or every 3–6 months in high-use or harsh environments.
Risks of skipping it:
- Missed leaks (false negatives)
- Rejected good packages (false positives)
- Regulatory non-compliance
- Failed audits or certifications
- Equipment drift leading to repeatability issues
Fix It: Set a recurring, logged maintenance plan for your detectors. Keep records of last calibration, parts replaced, and test verifications.
Remember: no leak detector is better than its calibration. Even a $10,000 system fails when it’s out of spec.
4. Incomplete Test Documentation
Without proper records, even accurate tests can fail audits or delay certification.
You ran the test. It passed. But can you prove it?
That’s what auditors, certification bodies, and regulatory partners want to know. And it’s why documentation isn’t optional. It’s a core part of ASTM-compliant leak detection, whether using D3078, F2096, or another method.
What should be documented:
- Method used (e.g., ASTM F2096)
- Package IDs, batch codes, and timestamps
- Operator identity
- Test conditions: temp, vacuum level, duration
- Equipment make, model, and calibration status
- Results: pass/fail, location of leaks, retests
- Corrective actions, if any
Fix It: Treat test documentation like a legal record—because it often is. Build templates that capture all necessary fields. Train operators not just on testing, but on recordkeeping.
5. Ignoring Environmental Testing Conditions
Variations in temperature, humidity, or altitude can distort test outcomes and invalidate results.
A flexible package that passes a leak test in New York might fail in Denver. That’s not hypothetical—altitude, humidity, and temperature all impact the sensitivity and reliability of leak testing.
Temperature shifts can change seal strength, alter internal pressure, or warp plastic layers. Humidity may weaken certain barrier materials or soften adhesives. And at higher altitudes, the reduced atmospheric pressure can throw off vacuum-based test readings.
Control Your Environment:
- Simulate real shipping or storage conditions when needed
- Document temperature, humidity, and elevation during test
- Adjust vacuum or pressure levels based on test location
Fix It: Test in the conditions your product will actually face. And if that’s not possible, document the differences and adjust your test sensitivity accordingly.
Your leak detector is only as effective as the process behind it. Testing the wrong way doesn’t just waste time—it gives you false confidence. And in packaging, false confidence is expensive.
Avoiding these five mistakes isn’t about perfection. It’s about repeatability, reliability, and protecting the brand you’ve worked hard to build.
