People in e-commerce or logistics often encounter this: a batch of products leaves with perfect seals, but arrives at the customer's end with leaks. The problem often isn't the seal itself — it's the "rough handling" during those days in transit.

Compression can indeed cause problems

Stacking, jostling, and tossing during transport all put pressure on the seal. Especially at the heat-seal area, continuous stacking pressure can create tiny cracks. There have been cases where honey products developed seal gaps due to transport compression, leading to inadequate sealing and total bacterial counts exceeding limits. More troublesome is that some damage isn't visible when the packaging looks intact — it only shows up after inversion or storage. And once a leak occurs, it can contaminate other products in the same batch.

These factors matter most

First is stacking pressure — products at the bottom bear significant weight, and the sealing film can be compressed and deformed, even developing micro-cracks. Second is impact and jostling — the tossing during sorting creates momentary liquid impact inside the bottle that can force open weaker bond areas, even if the seal itself was intact. Third is heat-seal parameters and strength — products with insufficient heat seal strength are more prone to problems during transport.

What you can do before shipping

Reinforce packaging protection: add cushioning materials inside the outer carton to reduce vibration and impact; control stacking height to avoid excessive pressure on bottom packages.

Optimize sealing process: ensure precise heat seal temperature, pressure, and time — especially for transport jostling, consider appropriately increasing heat seal strength standards. Perform random seal integrity tests before shipping to simulate stacking and drop conditions during transport.

Choose sealing film with better toughness: products with aluminum foil composite film plus elastic cushioning layer structure offer better impact and compression resistance.

If you're always worried about seals being compromised by compression during shipping, try sending a sample package to Leadtra Packaging via courier. We'll simulate actual transport conditions and test whether the seal holds up after stacking and jostling.