What Does Hermetic Mean?

Flexible plastics… just because they’re heat-sealed together doesn’t mean they’re airtight!

Without optimized heat sealing parameters and hermetic seals, flexible laminations won’t perform as designed, no matter how sophisticated the material is.

Hermetic heat seals are completely airtight. Depending on what kind of heat sealing equipment is utilized in conjunction with a film extrusion line (which is typically where poly carton liners come from) the line may or may not, produce hermetic seals. 

To achieve optimally strong seals, parameters must be developed for each different sealing device that defines a specific temperature to be applied, under specific pressure, for a specific duration of time. We achieve this consistently by using equipment with calibrated controls for temperature, pressure, and time instead of manual equipment, like an iron.

One other important consideration that’s often overlooked is geometry. Many heat sealing applications require sculpted seal bars to mirror the configuration of the films, or film and molded fitments, being sealed. 

For example, installing a molded fitment into the top perimeter of a side gusset bag will require applying a single seal that covers the fold of the side gussets and the top opening of the bag at the same time. That means the seal bars will hit areas with four layers of film, and two layers of film plus the fitment. When the seal bars do not conform exactly to the shape of the fitment and account for the difference in layers, a hermetic seal isn’t achieved.