Zalkin capping solutions for tethered caps


Tethered caps


In 2019 the EU voted the Single Use Plastics (SUP) Directive on how to deal with single-use plastic products. Under this Directive, in the future, drinks will only be allowed to be sold in plastic containers if the cap remains attached to the container.

Early 2021 National laws transposed from the Directive has come into force. This has made tethered closures an omnipresent topic in the packaging industry.

Zalkin Custom Development

Zalkin know-how allows to develop innovative capping applications, including lightweight and tethered.

The Directive on tethered closures highlights how crucial it is that designs combine circular economy and consumer-friendly closures. This is why Zalkin has worked hard with cap and packaging manufacturers to find solutions for caps that not only meet the sustainability requirements but also improve also consumers’ experiences.

With its ZC Lab test laboratory Zalkin has advised and assisted for developments on

  • Caps

Tethered caps have to offer customers the same physical performance as standard closures

  • Neck finishes

Closures ideally need to be implementable without the need for modifications to the neck finish and without any loss of efficiency in the handling processes

  • Capping process

Various solutions have been developed that can be adapted to all important bottle neck sizes

  1. with minimum conversion effort
  2. without negatively affecting the application processes


Since 2019, ZC Lab and tethered closures mean:

  • 800 hours of laboratory tests
  • over 20 applications evaluated

Zalkin has a large experience in tethered capped bottles for water

1. Snap cap for still water

  • Work on snap tethered caps since 2015
  • Approx. 100 Zalkin cappers in production since 2016

--> About 50% conversions – 50 % new cappers

--> Speed ranging from 10 000 to 70 000 bottles/hour

2. Screw cap for still & sparkling water

  • Work on screw tethered caps since 2019
  • 5 Zalkin cappers in 2020

--> 100% conversions

--> Speed ranging from 10 000 to 50 000 bottles/hour

Impact on PET packaging commercialization

Objective of this new directive

  • Reduction for marine littering, as plastic closures from PET bottles have been identified as a major cause for pollution and high risk for marine wild life (ingestion).

Proposed solution

  • To reduce/eliminate closures from separate littering by attaching closures to the bottle till the end of life of the bottle.


Tethered caps are not only snapped (like Roxane-Cristaline). In the EU definition, all closures for PET bottles for beverages should be converted to tethered by 2024.

Impact on environment & packaging collection rates

Reducing the impact of single use plastic on the environment

Beverage PET bottles will have to contain

  • From 2025 - at least 25% recycled plastic
  • From 2030 - at least 30% recycled plastic

Necessary measures to collect separately an increased amount of waste single-use plastic products for recycling:

  • No later than by 2025, amount equal to 77% (plastic products placed on the market in a given year by weight)
  • No later than by 2029, an amount equal to 90%

Impact on other liquid & dairy products

Tethered caps are not only snapped for water

Next to this first solution, cap manufacturers and packaging companies have developed tethered screw caps for PET bottles and worked on solutions for HDPE bottles/containers.

For example the snap clic originally for water PET bottle has already been adapted for dairy products and meet the SUP directive.