Closing arguments: The practicality and politics of wine closures


There is no question that cork is the current standard in closures, making up approximately 80% of the market. Cork is a natural product that is biodegradable. The production of cork is a job producing industry. It  is durable, flexible and easy to put back into a partially consumed bottle. Plus, the act of removing the cork from the bottle is much more theatrical than twisting off a cap.

However, cork taint has long been an issue. Cork taint is the presence of tricholoranisole (TCA) in a wine. If you notice the musty smell of wet cardboard in your wine, it is likely affected by cork taint, or corked. Many studies have been done on how many bottles are lost to cork taint, with some putting the number as high as 7-percent.

Synthetic cork:

To get around the cork taint issues, synthetic corks were developed. They are made from plastic compounds and have no issue with TCA. Synthetic corks look cork-like, and are extracted from the bottle with a corkscrew, just as natural cork.

However, synthetic corks are not biodegradable (but can be recycled). They are also more difficult to remove from the wine bottle, and can be impossible to reinsert once removed. There is also an issue with air getting into the wine bottle earlier than 20 months after bottling. And while TCA is not an issue, some find an unpleasant chemical taste in wine with a synthetic closure.


Nanocork is a recent technology that attempts to resolve issues with both natural and synthetic cork. It uses natural cork with a synthetic barrier bonded to the ends. It is touted to keep cork taint from affecting the wine, while permitting oxygen transfer equivalent to natural cork alone. Because it is a new technology, time will have to tell how well wines age when closed with nanocork.

Screw cap/Stelvin closure:

The screw cap, also known as a Stelvin closure, is rapidly becoming more acceptable. They are widely used in Australia and New Zealand. An initiative promoting the screw cap in New Zealand has resulted in about 90% of the wines from there being closed with screw caps. The newest versions of the screw cap have come a long way from the caps found for many years on inferior wines. They obviously eliminate the cork taint issue, and help maintain the quality of the wine by forming a tight seal that keeps out oxygen.

The ability of a screw cap to continue to benefit the wine for decades is not clear. Some tests have indicated that the caps start to deteriorate after 10 years. Additionally, some argue that wines that have issues with reduction, a chemical reaction that can cause sulfer-like aromas such as overcooked cabbage or bad eggs, experience problems with screw caps.

Still, the biggest problem with screw caps is their image. They are so linked in the minds of many with poor quality wine that marketing expensive bottles of wine with this type of closure is very difficult. And, as mentioned before, they take away the flair associated with opening a bottle of wine.

Vino Seal:

Vino-Seal, or Vino-Lok, features a glass or acrylic stopper fitted with an o-ring that is placed in the bottle and covered with an aluminum cap. These closures are used often in Germany and some areas of Italy. Vino-Seal does a good job of preventing oxidation of the wine, and of course, eliminates cork taint. It is also easy to remove from the bottle without the use of special equipment, and is easy to put back in the bottle if you don’t finish your wine. It is an elegant looking closure, with few disadvantages. The biggest drawback for wine producers is the high cost of each stopper.

[image-1] Zork:

If you really need to hear a pop when you open a bottle of wine, look for one with a Zork closure. The Zork features a plunger with small grooves in the side to help force air out of the bottle. When removed, the plunger makes a satisfying popping sound. It is covered by a cap with an inner metal foil to keep the plunger in place and provide a good oxygen barrier. The cap is what makes this closure so different from others. It is often brightly colored, and peels off in a long strip similar to the top of a milk jug. Once again, the Zork can be removed without any equipment.

How a closure affects the wine in a bottle is not the only consideration in choosing a type of closure. The choice can be surprisingly political. In addition to the obvious environmental benefit of cork being biodegradable, cork is also biodiverse. A concern is that if cork is not in as great demand, prices will drop and cork will ultimately be replaced with crops that are more profitable, but less sustainable.

Cork is also big business and supplies jobs. The cork industry also spends a great deal on research and on lobbying efforts. To help preserve the industry one of the world's biggest cork producers, Spain, has prohibited non-cork closures for Denominacion de Origen wines in 11 regions. Another cork producer, Italy has passed similar legislation. However, alternative closures are still seen among winemakers who are less concerned with falling into a category, and more concerned with the actual quality of the wine they produce.

It is impossible to tell what type of closures will prevail. Cork still maintains 80% of the market, and cork producers are trying to overcome the problems associated with cork. Just know that the next time you buy a bottle of wine, you can’t judge it by its closure.

To read what and where Colleen is eating and drinking, follow her on Twitter @colleensachs.

One of my favorite wines is Two Hands Brave Faces (particularly the 2005 vintage). It is a wonderfully jammy shiraz grenache from Barossa Valley, Australia. It is a delicious big boy of a wine with 15% alcohol, and a price tag of nearly $40 —a nd it has a screw cap.

While cork still dominates the market, screw caps and other alternate closures are becoming more prevalent in upscale wines. Screw caps are no longer relegated to mass produced inferior wines, and new types of closures are being created all the time.

There are pros and cons to each type of closure, and even some strong ecological reasons for keeping cork around. The following is information about common closures seen on the market today.

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