Sealing glass and ceramic is more complex than sealing plastic containers. Furthermore, conduction heat sealing machinery doesn’t always work on all glasses and ceramic containers, and there is an explanation for this.

As we previously mentioned on our LinkedIn profile, the process of thermo-sealing will never be able to provide a perfect hermetic seal on a glass or ceramic container that doesn’t have a completely flat surface. Keep reading to find out why.

Things to consider when deciding whether to use heat sealing on glass and ceramic containers

Heat sealing, or thermo-sealing, has been around for decades and is well-established across many industries. It is simple and inexpensive so has long been the default technology used to seal a container, whether it was plastic, glass, ceramic or metal and in most cases, users just accept the associated disadvantages.

However, technology has advanced and direct induction sealing systems can now be used to solve many issues that heat sealing machinery presented when sealing a variety of products, especially glass or ceramic.

So, what is happening when using a thermo-sealing method to seal your glass or ceramic pots?

Let’s go step by step:

1. The conduction head sealer, or thermo-sealer, has a rigid non-compliant surface.
2. Glass and ceramic containers don’t have a complete flat sealing surface and can’t be melted like plastics.
3. A hermetic seal requires for one of these to change.

And what does it mean?

1. With a hard contact surface on sealing head, the impression/contact area on the container will be uneven and incomplete.
2. You are only getting a seal in the areas where you can apply pressure.

How can we solve this issue?

Relco has found a solution for this seal impression problem on glass and ceramic containers. Relco’s technology uses two important things to be able to create a perfect hermetic seal.

1. A specially designed composite rubber pad to guarantee perfect contact between sealing foil and container. (Picture 1)
2. An optimized induction coil to focus the induction field on the sealing area of the foil.  This field passes directly through the rubber pad without causing any heating effect as it is non-conductive, delivering the heat straight to the foil to achieve a perfect seal. (Picture 2)

 

To conclude

Relco’s direct induction sealing technology solves many issues that heat sealing can’t such as leakage or seal inconsistency.

Relco’s induction sealing heads use a flexible silicone-rubber surface and the sealing pressure needed to create a seal comes through this material. The foil is wrapped around uneven top surface of the glass or ceramic jar, and during the induction heating process, the foil is perfectly sealed around the entire surface of the jar even if not flat.

Contact us if you have any questions about the sealing process of glass and ceramic.