The eternal youth of the Crown-Cap

The crown cap is an interesting case

 

 

Invented at the end of the 19th century

by William Painter, an American of Irish descent, it emerged as the economic and efficient closure solution for carbonated drinks. This was a time when sodas were gaining in popularity and today’s leading brands were founded. While previously, both bottles and closures had been designed to be reused, the crown cap inaugurated a lightweight and disposable form of closure. Furthermore, the fitting of caps was well suited to mechanisation, and Mr Painter went further by inventing the machine to bottle sodas with crown cap closures, which was the precursor of modern bottling machines. At the start of the 20th century, the mechanisation of bottle production also made it easier to produce the crown finish, which was quickly and widely adopted for sodas and beers.
Even though they are more than 120 years old, the drawings of the caps in Mr Painter’s patent are surprisingly close to today’s versions. The crown cap is still the ruling closure system for beers and alcohol-free drinks in glass bottles.
 
In fact, the Cetie was founded as a result of the crown cap. Our organisation was founded in 1960 at the initiative of brewers and their packaging suppliers, who were looking to make bottling with crown caps, in particular, more reliable, following the revelation of certain weaknesses further to the rise in production rates. The goal was to bring together inter-professional experts to draw up pre-standards and good practice, and this remains the foundation of Cetie’s actions today. The problems that existed at that time were solved through discussions and exchanges, as Cetie extended its actions to include other problems related to bottling.

 

"There is no European standard for crown caps"

 
But the venerable crown cap, which had already come under Cetie’s scrutiny, continues to evolve. Changes include the reduction of the thickness of the metal, which meets both environmental and economic goals, and the profile and the material of the liners, which must fulfil the functional requirements and meet the increasingly strict demands for inertia in the event of food contact. Plans were already afoot to review Cetie’s reference documentation for crown caps to take these developments into consideration when an unexpected opportunity arose to do so anyway. The Turkish standardisation organisation (TSE) filed an official request with the European Committee for Standardisation (CEN), of which it is a member, to produce an EN standard for crown caps, using a recent Turkish standard as a working basis. The request struck a chord with the corresponding CEN working group, which gave a positive response to the TSE and asked Cetie to prepare a draft pre-standard.
 
There is no European standard for crown caps, although the German standard DIN 6099 is currently used as a reference document. The Turkish standard took the core of the DIN standard and added acceptance tests and acceptability criteria, also inspired by existing German reference documents.
 

The Cetie set up two working groups:

one for crown cap manufacturers and the other for all of the players involved. The work in progress has confirmed that the bottlers - brewers and producers of alcohol-free drinks - expect the reference documents to be adapted to take the changes in the market into consideration, while still fulfilling the primary function of a standard, which consists in defining the conditions that guarantee a compliant result. The task has been complicated by a number of factors:

• The reduction of the thickness of the metal from 0.22 mm to 0.20 mm or 0.18 mm is now an industry practice, put it demands additional precautions when fitting
• Crown caps are produced for several markets with their own specific demands, especially in terms of heat treatment (pasteurisation, hot filling, sterilisation)
• The liners are adapted to each application and, to a certain extent, can be a factor of technical differentiation between suppliers
• The diversity of the size and technical resources of the companies that use crown caps, which range from worldwide brands of beer and sodas, to SMEs, and traditional brewers in particular

At this stage, some uncertainty still surrounds the form of the pre-standard proposed by Cetie, in view of the difficulty of reconciling all these aspects in a single document. In particular, discussions are ongoing about the possibility of producing, on the one hand, complete dimensional specifications, including the thickness of the metal, that represent an application of proven robustness, and, on the other, proposing an opening for reduced thicknesses, with specifications applying to criteria of performance in defined qualification tests.
 
As usual, bringing together experts representing the different stakeholders should allow us to reach an agreement on a useful common language and understanding. A European standard for caps must be part of a set of reference documents that include glass finishes, for which a standard for the twist-off version is also in demand. The fourth edition of the Cetie Bottling Guide also needs to be revised and to take account of the changes in the documentation available elsewhere.
 
The wealth of experience and the vitality of the crown cap seems to be a source of eternal youth, even at the age of 120. PDF (FR) :
- Liquides & Conditionnement N°377 (June-July 2015) (FR) Tags :

Glass container

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Crown cap

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Standardisation