What Does “Hermetically Sealed” Mean?

You have probably seen the phrase “hermetically sealed” on packaging, lab equipment, medical products, or in a sci-fi scene where somebody is very serious about a door staying shut. The phrase sounds a little dramatic. In manufacturing, it has a very practical meaning.

A hermetic seal creates an airtight and watertight barrier. Air, vapor, dust, fluids, and outside contamination stay out of the sealed area. The material inside stays protected too. This is huge for products used in healthcare, military gear, industrial equipment, protective covers, inflatable products, & other applications where leaks can cause real trouble.

At Vinyl Technology, a hermetic seal usually comes from heat sealing, RF welding, or other bonding methods that join materials into one sealed surface. A sewn seam can leave tiny needle holes. A welded seam creates a cleaner barrier because the materials bond together under heat, pressure, or radio frequency energy. Sounds simple enough, but it’s a precision and expertise that is necessary.

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What is the History of Hermetic Seals in Manufacturing?

The word “hermetic” goes way back. It comes from Hermes Trismegistus, a figure tied to Greek and Egyptian mythology. Old stories credited him with the ability to seal glass vessels so tightly that outside air could never reach what was inside.

That ancient idea still sits at the center of modern hermetic seals. A sealed vessel protects what it holds. Manufacturing took that basic idea and gave it better materials, better equipment, and much higher standards. Today, a hermetically sealed product may need to resist water, air, chemical exposure, pressure changes, or contamination during daily use.

For Vinyl Technology, that means the seal has to match the material, the product, and the end use. A medical pouch, protective cover, flotation device, or industrial bladder can each need a different sealing approach. Same goal though: a barrier that holds up when the product has to perform.

What Are the Methods of Creating Hermetically Sealed Products?

There are many ways to create a hermetic seal that is both waterproof and airtight, and none of the current methods involves magical incantations. A common method in use at Vinyl Technology would seem like magic to the ancient Greeks and Egyptians: RF welding.

This is a process that’s known by many names: dielectric sealing, RF sealing, RF welding, and heat sealing. They all describe the same high-tech method of joining thermoplastic films using Radio Frequency (RF) energy.

Those RF waves excite the molecules of the materials to be joined from the inside out, fusing the materials. It doesn’t leak air, moisture, water, or fuel, whichever of these is crucial to your application. 

Unheated Heat Sealing 

Although you might hear “heat sealing” used to describe it, that’s not entirely accurate. There is no heat involved in RF Welding. A table-top heat sealer used to preserve leftovers creates what would commonly be called a hermetic seal in manufcuring, but it’s not exactly the same. RF Welding happens at the molecular level, binding two materials with a seal much stronger than any household appliance can do.

PVC Sealing

PVC sealing is a high-frequency welding process that allows for the application of PVC (Polyvinyl Chloride) to a soft fabric or film. PVC has the advantage of being lightweight, durable, and abrasion-resistant, and is often used in waterproofing fabrics. PVC is considered to be an excellent material for radio-frequency welding because of its strong dipolar moment and other chemical properties.

Vinyl Technology uses this sealing in the manufacturing of many products, such as Anti-G suits, pneumatic pillows, and self-inflating mattresses.

If you’d like to learn more about what heremtically sealed means and the different uses Vinyl Technology can make for your needs, get in touch with us today.

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