Seal Integrity Testing Methods Compared
From dye penetration to vacuum decay — choosing the right leak test.
By PPI Technologies Group · · 7 min read
Key Takeaways
- Destructive tests (burst, peel, dye) are simple and cheap but consume product
- Non-destructive tests (vacuum decay, pressure decay) keep saleable product and enable higher sampling
- ASTM standards exist for most common methods — cite them in your quality plan
- Match test sensitivity to the leak size that actually threatens your product
- Combine an inline check with periodic lab testing for full coverage
Why a single method is rarely enough
Different tests catch different failures. A burst test tells you seal strength but not whether a tiny channel leaks. A dye test finds channel leaks but destroys the pack. A vacuum-decay system finds leaks without destroying product but needs the right sensitivity for your package. Robust programs layer methods rather than relying on one.
The common methods
What each test actually tells you:
- Burst test — internal pressure to failure; great for seal strength trending (ASTM F1140 / F2054)
- Peel/tensile test — force to separate a seal; verifies peelable seals and strength (ASTM F88)
- Dye penetration — visual detection of channel leaks in seals; cheap and destructive (ASTM F1929)
- Vacuum decay — non-destructive pressure-based leak detection, increasingly automated (ASTM F2338)
- Bubble/leak emission — submerge under vacuum and watch for bubbles; quick gross-leak check (ASTM D3078)
Sensitivity vs. relevance
Chasing the smallest detectable leak isn't always right. Decide what leak size actually matters for your product's shelf life and safety, then pick a method sensitive enough to catch it reliably — without flagging harmless imperfections that tank your yield.
Real scenario: MAP tray line
A modified-atmosphere tray line used periodic destructive burst testing but still had gas-loss complaints. Adding inline non-destructive leak detection caught micro-leaks on every pack, while keeping the burst test weekly for strength trending. Complaints dropped and far less product was scrapped for testing.
Bottom line
Write your seal-integrity plan around the failure modes that threaten your product, cite the relevant ASTM methods, and pair a high-coverage non-destructive check with periodic destructive testing. Verification is what lets you stand behind your shelf life.
Equipment for this topic
Machines and brands we supply that apply to what you just read.
- Herrmann Ultrasonics TSM Top Seal Modules — Herrmann Ultrasonics · Sealing: Ultrasonic top seal modules for hermetic, contamination-free package sealing without heat — ideal for temperature-sensitive products.
- PSG X-Ray 4500DP — PSG X-Ray · X-Ray: High-performance dual-perspective X-ray inspection — two viewing angles eliminate blind spots for maximum detection coverage.
Browse the full line-up
- PSG X-Ray — X-Ray Inspection
- Herrmann Ultrasonics — Ultrasonic Sealing
- Inspection & Quality Control — All 23 machines
Buyer's guide: X-Ray Inspection Systems
Sources & Further Reading
- ASTM Committee F02 on Primary Barrier Packaging: seal strength and leak test standards — ASTM International
Frequently Asked Questions
What is seal integrity testing?
It's a set of methods that confirm a package seal is complete and leak-free, including burst, vacuum-decay, and dye-penetration testing.
What's the difference between destructive and non-destructive seal tests?
Destructive tests (burst, dye penetration) sacrifice the package. Non-destructive tests (vacuum decay) preserve it, which allows higher-rate or even inline testing.
How often should seals be tested?
Per your quality plan — typically routine sampling at startup and at intervals, with inline testing for critical products.
Keep reading
- Hermetic Seals: What They Are and Why They Matter — The difference between a package that looks closed and one that's actually sealed.
- Modified Atmosphere Packaging (MAP) Basics — Changing the air inside the pack to buy days, weeks, or months of shelf life.