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The production of wine dates back thousands of years and, perhaps because of that, people have been reluctant to accept new-fangled ideas.

In recent years, however, more and more vintners have moved their products from natural cork to screw tops as the preferred closure format. While cork still has a commanding presence in the market – around 10 times as many bottles of wine use cork than use screw caps – the number of bottles sold globally with screw tops increased by 131% from 1998 to 2006, compared with 2% growth for cork closures, according to Euromonitor International.

The move to screw caps was initially popular with wines from the new world – screw cap penetration in New Zealand and Australia is 85% and 45% respectively – but European vintners are now starting to follow suit.

Pernod Ricard is among those to have made the switch. After the successful introduction of screw caps for its Australian Jacob’s Creek wines at the start of the year, this autumn the drinks manufacturer is extending the format to its Spanish Campo Viejo lines. Wine development director Adrian Atkinson says the move will “safeguard the quality and consistency” consumers have come to expect from the brand.

“Stelvin closures preserve fruit flavours and freshness, delivering the wine exactly as the winemaker intended,” he adds. The most common reason for moving away from cork is that it taints the wine – between 5% and 10% of wine in bottles with cork closures is estimated to be ‘corked’.

Part of the problem with natural cork is that it comes in different qualities, which is reflected in the price. “Grading of cork is a contentious issue, because it is open to interpretation and you don’t always get what you expect,” says Mike Bullock, packaging technologist at drinks manufacturer Constellation Europe.

Constellation has gradually moved some of its lines over to screw caps, but others, such as Banrock Station, remain in cork. “With lines that are drunk within a few days of purchase, people are happy with screw caps, apart from a small minority who swear by natural cork,” says Bullock.

Convenience closures
This is echoed by Tim Croxson, operations manager at closure broker Croxsons. “Consumers spending a lot of money on wine typically want an old-fashioned cork, but those spending £5-6 a bottle are not really fussy. Closure type is not really an issue.”

Croxson also suggests that part of the reason for the growth in the use of screw caps is convenience. “It’s much easier for people to take [wine with a screw cap] on a picnic,” he says.

British Glass technical manager Peter Grayhurst says the move to screw caps is not just driven by what’s good for wine, but also by the amount of wine being consumed. “Sales have exploded and it’s difficult to get hold of sufficient quantities of natural cork,” he says.

Synthetic corks suffer from inconsistency in the material and problems in achieving the right seal with the bottle. This is because it is easier to control the surface on the outside of the bottle than inside the neck – one of the key attributes of natural cork is that it expands to fill any voids on the neck of the bottle.

Despite their success, screw caps clearly have some way to go before they overtake natural cork. Indeed, cork still seems to be the preferred option for more expensive wines. That said, there are some other products waiting in the wings, such as the Vino-Lok and the unusually named Zork.

Over the past three years, US aluminium products supplier Alcoa has gradually rolled out its Vino-Lok system after initial success in Germany. Vino-Lok is a glass stopper with a rubber seal, which is secured on the bottle with an aluminium cap. The company says the advantage of using glass is that it has a “neutral taste” and provides “the highest level of product safety”. Furthermore, it is completely recyclable.

Developed and manufactured in Australia, the Zork is made from an injection-moulded food-grade polymer. It is made in three parts: a ‘plunger’, which sits in the neck of the bottle; a layer of foil, which provides a barrier to oxygen similar to a screw cap; and the cap, which goes on top and fixes it onto the bottle.

The company says that, as well as preserving the wine, Zork is easy to open and reseal. It also says that adapting a three-head screw cap line to use the closure takes less than 15 minutes and an investment of around £2,650 (AU$6,000).

With a few exceptions, closure development for wine has been fairly static. In comparison, there has been significant change in spirits bottles.
 
Closing out the counterfeiters
Closures have become increasingly important for spirits manufacturers because of the growing threat from counterfeit products, particularly in the former Soviet Union and Asia. There is clearly profit to be made from filling original containers with sub-standard products and then passing them off to a naïve customer as the genuine article.

The result is that distilleries are increasingly seeking closure formats that make it impossible to refill the bottle, which requires increased co-operation with glassmakers and closure makers. “New closure development requires a very complex technical relationship,” says Gilles Desheraud, O-I Europe’s spirits marketing manager.

It is possible to place a device in the neck of the bottle that prevents refilling, but from the manufacturing perspective this requires very tight specification of the bore diameter to ensure “a snug fit”. It is equally important that the bottle is compatible with other closure formats, so filling lines can be used efficiently for a range of products.

But the biggest problem is that counterfeiters are often very adept at finding new ways to get their products into the bottle, meaning that closures have to be constantly updated.

“The speed with which the counterfeiters overcome security features makes this a very steep learning curve for everyone involved in the legitimate spirits trade,” says Desheraud.

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CROWNING MOMENT
Unlike cork in the wine market, the crown is showing no signs of relinquishing its dominant position in beer and cider. What is essentially a piece of punched metal with a plastic liner has, so far at least, seen off all the competitors. Simplicity has been key to success. As well as being the cheapest closure type available for the sector, the crown’s form makes it relatively easy to apply to filled bottles at high speed.

The opening of the bottle is also fairly simple to make and less prone to flaws when compared with other methods such as screw caps, according to Craig Wilson, packaging development manager at brewer Scottish & Newcastle UK.

“Crowns make life a little easier [for bottle manufacturers],” he says. Furthermore, they are robust and effective at stopping gas escaping or things getting in that might spoil the contents.

That’s not to say S&N would not consider other formats if they “better met consumers’ requirements”. Bulmers Original cider, for example, is already sold in one-litre bottles with screw caps so it can be resealed.

Wilson admits that crowns might not be the easiest format to open – teeth aside, they generally require a tool – but their ubiquity means most cutlery drawers hold at least one bottle opener.

“Licensees also prefer them to screw caps because, with a bar-mounted opener, they can be quickly opened with one hand for fast customer service.”