A Word About Wine Closures

A Word About Wine Closures

Many Swiss wines are known for their screw cap closures, which have contributed to a reputation that some consider as cheap. But screw caps may actually perform much better than their image indicates. The screw cap closure alternative is a perfect solution for wines which are meant to be consumed young – of which there are plenty in Switzerland. There may even be reason to support this closure method for wines which need years of aging. Unfortunately, screw caps just don’t have that romantic feel that comes from opening a bottle and hearing that familiar plop from the cork…and even the Swiss have not yet figured out how to solve this problem.


The use of cork as a wine bottle closure has a long tradition and has gained acceptance with wine consumers, producers and industry professionals. Cork is a natural product that literally grows on trees. With time and careful handling, cork trees continuously supply the industry with a closure solution despite their faults. Cork-tainted wines plague the industry, but consumers have surprisingly accepted this burden as a destiny coming from the use of a natural product. Additionally, the wine industry continues to expand; it is growing faster than the cork supply can replenish itself. But consumers remain apprehensive about leaving behind the sacred ritual of pulling a cork out of a bottle. And so the industry obligingly carries on, and corks remain the number one wine closure solution.

Technically, cork plays an important role in the development of the wine. Wine is not dead once it is bottled. Wines continue to develop their character, and cork can help the wine in this maturing process by allowing a certain gas exchange to occur through the cork’s porous structure. But all corks are not created equally. Some corks seal the bottle too well, and certain unwanted aromas are trapped in the wine. Rotten eggs, rubber, vegetables, and over-cooked cabbage are a few examples resulting from a cork that functions too well. On the other hand, if a cork is too porous, then too much oxygen will enter into the bottle and create unwanted aromas of walnuts or apple skin. These oxidized wines can also appear flat in flavor and lacking in fruitiness. Cork taint (wines affected by the aroma of cork) is another problem affecting about 4% of the worldwide wine supply. Despite recent improvements to the quality of cork, most experts believe this percentage is still too high. Since most cork manufacturers are often small and do not have enough money to invest in quality control or newer infrastructure, the problem of taint is likely to remain. Additionally, the cost of a single cork is expensive at one euro, and producers are accelerating their search for alternative closure methods.

Consumers may see the romantic side of corks, but manufacturers are increasingly looking at the business side of closing wines.

A Variety of Closures for Swiss Wines

A Variety of Closures for Swiss Wines

Screw Caps

Using screw caps as an option to replace corks seems to have the brightest future, but their use also creates the most controversy within the wine industry. Screw caps are widely used to successfully close a variety of beverages, but their acceptance by the wine industry has been quite limited. Recent trends seem to indicate a more rapid adoption by the industry, as wine producers seek lower-cost and more reliable solutions. Consumer reaction, however, remains skeptical and guarded. In the past, screw caps were always used to close cheap wines of poor quality, and this image remains deeply embedded within the consumer’s mind. Helping to change that perception and showcase the positive aspects of using screw caps is Switzerland. Screw caps on Swiss wines actually have a long history, and the wine industry is profiting from this experience.

Screw cap manufacturers guarantee three years of harmless storage for beverages. Swiss studies seem to support this claim, as wines stored even longer (10+ years) remain in perfect condition. In comparison with wines under cork, wines which have been closed with screw caps for the same amount of time appear much fresher and younger. The Swiss experience seems to indicate that it is theoretically quite possible to store wines, even those with long storage potential, for quite a long period. Some top producers agree. Cloudy Bay now uses screw caps to close their top sauvignon blanc. Even French producers have budged. Chateau Pichon Longueville puts their second wine under screw cap – even though they only do this for the English trade market (wines going mostly to restaurants).

There isn’t much industry doubt about the effectiveness of screw caps – especially for young wines which are meant to be consumed within 2-3 years. Screw caps must, however, evolve and solve a few nagging problems before more wine producers replace corks. Screw caps seal the bottle so well that important exchanges of gas fail to occur, and the wine suffers from trapped unwanted aromas. About two-percent of all wines closed by screw caps have this problem, which is quite similar to the problem existing with corks (mentioned earlier). A second problem occurs in the capping stage. Not all bottle shapes can be capped by the currently available mechanisms. Further, a producer may have to invest in multiple machines to cap different bottle shapes, which obviously drive up production costs. Once on the bottle, screw caps face a different challenge. Sometimes, the cap does not function correctly and the entire screw mechanism simply turns around the neck of the bottle. These flawed closures are quite difficult to open once they fail. Another opening problem occurs with older people, who have complained about the difficulty in opening screw caps.

Technically, screw caps seem to function extremely well and may be the solution for manufacturers. Realistically, consumers still make negative associations with screw caps, and they are not yet ready to give up on the ritual of pulling a cork out of a bottle of wine.

Synthetic Corks

Synthetic corks made from silicon have more consumer appeal than screw caps, but their performance is quite questionable. On the plus side, synthetic corks are neutral in taste, easy to produce, available in almost any color, and cost less. Consumer acceptance is quite good, even though cork screws suffer from an increased strain. The problem with silicon stoppers is they do not perform as well as cork. Silicon’s elasticity is not as good as cork, and the seal around the bottle suffers. For this reason, silicon stoppers can only be a viable option for young wines, which should be consumed within 2-3 years.


This glass stopper is fairly new, and it has caused a bit of an uproar in the wine world. This alternative was quickly accepted by consumers because it is made from the same material as the bottle. But, glass on glass does not make an effective seal, so a plastic ring must be used, which adds complexity and costs in the production. Currently, the biggest challenge for this method is in the bottling stage. Machines are not able to produce constant results, and different bottle sizes are proving to be a difficult challenge. Bottling machines are quite expensive, so this option would not really work for the small producer. There are no real results on how well a wine ages under glass. Three-year studies are favorable, but more time is needed.

Crown Caps

Crown caps are widely used in the production stage of sparkling wines, and of course, they have been used for years to close beer and soda bottles. Within the wine world, crown caps have only been used to close relatively inexpensive wines in one-liter bottles, which are primarily marketed to restaurants as cooking wines. Crown caps create an air-tight closing, and for this reason, they are not really an option for any serious wine producer.

In Closing…

Cork is steeped in tradition, and that will be difficult to eliminate – especially in the hearts of many consumers. But, wine production continues to grow, and could rise even more if the large Asian markets begin drinking more wine. New closure solutions are clearly in demand, and there is little doubt that many wines – especially wines meant for early consumption – will have something other than cork keeping them closed.