How to Foil Seal Plastic Bottles with Induction Sealing

Many food products, like spice blends, require foil seals to lock in freshness, prevent leakage and protect products from tampering. For example, our empty spice jars are sold with lids and foil seals.

But you might be wondering: How do you actually foil seal plastic bottles? How do we make the foil seal bond to the bottle?

The answer is simple: Heat induction.

Induction sealing is the process of using induction heating to create a permanent bond between the foil seal and the plastic jar. The result is a tamper-evident seal that’s airtight and secure.

How Does Induction Sealing Work?

With induction sealing, a foil liner is placed underneath the cap on a bottle or jar. A heating head from an induction sealing machine is then placed over the cap and non-contact heat is applied.

This is completely non-contact, as contact heat would likely melt the cap and jar.

The head generates an electromagnetic field that heats up the foil under the lid. As the foil heats up, it melts a coating on the underside of the liner. This melted under-coating, along with the pressure from the closed lid, then create a hermetic seal, or a seal that is airtight.

Ultimately, the foil liner adheres to the bottle or jar, and must be removed before the product can be used by the customer. That’s why it’s often called a tamper-evident or tamper-resistant seal.

Do You Need an Induction Sealer to Foil Seal Bottles?

Yes, you do an induction sealer to properly adhere the foil seal.

Fortunately, handheld heat induction devices are fairly affordable, which would be a sound investment for small businesses, small spice companies or DIYers looking to expand.

How Do You Test Induction Seals?

Testing foil seals can be difficult without a high-tech seal tester. But there are a few methods you can use to test your seal for tightness, including:

  • Visual Inspection – Make sure the seal is sitting flush on the top of the bottle. Look for any gaps or places where the liner has crinkled back creating an opening.
  • Squeeze Test – If the seal passes a visual inspection, try to gently squeeze the bottle. The seal should continue to adhere without movement. Squeezing the bottle will reveal if the liner hasn’t properly bonded in some places.  
  • Flip Test – You can also try flipping the bottle upside down, which is especially useful if it is a liquid. This will reveal any potential leaks.

Ultimately, if the seal hasn’t adhered properly, you can remove the faulty seal and repeat heat induction process.  

What Are the Benefits of Foil Seals? 

Foil seals offer numerous benefits for food and beverage brands, cosmetics businesses, and many other consumer product companies. For example, foil seals:

  • Inspire Consumer Confidence – Foil-sealed bottles for food items or cosmetics will instantly increase brand perception. Perceptions of your product’s quality, safety and freshness will all increase.
  • Product Your Products – With a range of products, an airtight seal will lock in freshness and prevent leakage.
  • Help You Meet Compliance – Some consumer products require safety seals. This type of seal may help you meet any food-safety regulations.

Shop Our Foil Seal Jars and Spice Containers

MHO Containers offers a full range of wholesale bottles, jars and plastic containers. Our foil seal spice bottles include screw-on shaker lids and foil seals. All you need is an induction heater to properly seal them.