The closing act

If you drink wine, then you can’t help but notice what closes the bottle. There’s been lots of controversy about wine closures over the years…some good, some bad. Let’s take a closer look at what’s out there.

The oldest known form of closure is the “natural cork” dating back to sixth century Italy. Cut in whole from the bark of a specific oak tree called “quercus suber,” it remains one of the most eclectic, recognized, expensive and best products for the job. Why? It is porous and allows minute bits of air into the wine to help evolve it. It also allows for the use of a corkscrew that historically and magically retains the romance of opening a bottle. However, it is not without its problems. It is prone to a little contaminant called TCA (2,4,6-trichloroanisole) that makes the wine smell musty/mouldy.

Although cork producers have spent mega-bucks to solve this problem, it still exists, to a much lesser degree. That said, it’s still the closure of choice for most premium wines that require aging.

Then there are “technical corks.” Still created from the bark of the same oak tree, they are conglomerates of cork pieces, usually ground up and stuck together through a molding or extruding process. Some have a cover on the outside, looking something like a bologna in a skin. They are less expensive to produce and still allow for a corkscrew, maintaining the “romance” factor of opening a bottle. Not quite as prone to the TCA contaminant, they tend to be used for more commercial wines.

Up next are “synthetic corks.” These plastic or polyethylene versions looking just like regular corks, and are available in all sorts of Day Glo colours. The positive note about these is that they totally eliminate the possibility of TCA contamination and still require a corkscrew. However, there are some drawbacks.

Being plastic, they do not allow any oxygen into the wine for evolution, are often extremely hard to extract from the bottle, and are almost impossible to push back in if wine remains. There are also some concerns about the concept of an oil-based product in contact with alcohol and the possibility of it leaching into the wine. They are mostly used for commercial wines.

Enter “screw caps.” There was a time when these were strictly limited to low end products, but in today’s world, many premium wines now use them. New Zealand and Australia adore them. One of the main reasons they have become so popular is because of the TCA taint in cork closures that is totally eliminated here. Made of metal with a liner of sorts, these styles do not allow for micro-oxygenation. They’re really easy to open and re-close. They certainly don’t maintain any “romance” factor and, although more accepted by the consuming public, they still suffer from an identity problem.

Other closures for wine exist. There’s something called “the Zork.” It’s an interesting invention that has a plastic cap, foil lining and a plunger that creates a ‘pop’ when opened. No corkscrew is required and it can be used to reseal the bottle. TCA taint is not an issue here. Then there’s the “Vino-seal” or “Vino-Lok,” a glass closure that sits on a synthetic O-ring and is held in place by a removable aluminum cap. There’s even a Guala Group synthetic GS Elite closure “made of a chassis for adherence and elasticity, the body for oxygen permeation, and a shroud that remains in neutral contact with the wine.” No doubt, all three of these closures are expensive for producers to use.

As a producer, deciding which closure to use is a big question. It depends on the varietal, wine style, whether the wine is age-worthy or not, the market, the winery’s budget and image. It will certainly be interesting to see how wine bottle closures evolve as time goes on.


Edward Finstein is a wine writer, award-winning author, TV and radio host, educator and judge   –   –   @DrWineKnow   –   –   Pinot Envy at

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