Passion for Packaging Innovation

Tamper proofing closures

There are two methods of implementing tamper prevention devices on food packaging. One method is to provide evidence when the package barrier is broken. The other method is to tamper proof the package. While these two methods may seem similar, they are indeed quite different.

Tamper Evidence

When a screw cap or a sports cap is wrapped in shrink film, it can provide evidence of tampering. If the film is damaged or removed, it becomes evident that the drink may have been opened before.

There are many different implementations of this, not only in beverage packages, but in many other kinds of packages. The pull-ring on a family-pack of juice, the shrink wrap on any kind of cap, and the straw hole in carton packages are all examples of this kind of tamper evidence device.

In many cases, the tamper evidence requires physical removal, negatively impacting package usability. These devices are typically made hard to remove to survive shipping and distribution. In addition, once they are removed, the user typically ends up with a piece of packaging in his or her hand that needs to be discarded prior to consumption.

On the positive side, consumers appreciate the peace-of-mind that the act of physically breaking the seal brings. Therefore, this tamper device is typically suitable for the family-pack format or in-home occasions, but it is not as appropriate for the portion-pack format or on-the-go occasions.

Tamper Proof

This type of tamper device appears on many types of packages, most commonly as the screw cap tamper ring. During opening, the ring separates from the cap, making it obvious that the package has been opened. While the ring itself is not part of the barrier, as in tamper evident systems, it serves a very similar purpose. In this case, the broken tamper ring acts as a proxy for the broken barrier.

There are a number of variations of this type of device. On carton packages, there may not be a ring at all, but instead a bridge that is ultrasonically welded to the shoulder. This is due to the lower profile cap design needed for higher distribution efficiency. Metal caps on glass water bottles may have plastic inserts that flare out once broken.

Package Usability

Tamper proof devices tend to be more friendly from a package usability point-of-view. The reason for this is their one-action, or one-step opening. The tamper evident systems mentioned before typically require a two-action opening.

If you are opening a cap with a tamper ring, you twist the cap in one single action, and it opens. If there was barrier film inside the cap to act as a tamper device instead of the tamper ring, then you’d have to physically remove that barrier film after opening the cap as a second action. This causes lower efficiency and effectiveness. The lower efficiency is due to the longer duration required for opening the package. The lower effectiveness is due to the higher error potential, which is caused by an increased number of actions.

Product Safety

On a number of packages, such as the gallon milk jug in the US, the tamper ring is not retained on the package once the seal is broken. Unless the user specifically removes and discards this ring, there is a potential for the ring to fall into a glass during pouring. This is made more likely as the consumption numbers aggregate to many billions in some of the higher volume packages. We’d like to see all manufacturers retain the ring on the package.

Two Tamper Devices are Surely Better Than One, Right?

The short answer to that question is “No.” We have seen a number of packages on the market that try to stack up more than one tamper device on the package. That, however, has the potential to reduce the clear signal that a single tamper device provides. If one device is broken and the other can be bypassed or faked as intact, then the consumer may assume that the product has not been tampered with when, in fact, it has. In developing markets, we have seen this happen.


A single tamper proof design with a single-action opening is the preferred tamper device. Tamper rings need to be retained.

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