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Don’t Judge A Wine By Its Top

As if analyzing what’s in the wine bottle isn’t complex enough, we now have to factor in the myriad of wine closures available into our wine evaluation equation. Are corks the only acceptable closure option? Are screw tops just for “cheap” wines? And what about artificial corks or even glass tops? Let’s learn about wine closures, so we can gain some…ahem…closure and get on with enjoying our wine.

Natural Cork: Old School

Since the 1400’s, natural corks, which are made from the bark of the Quercus suber tree, were the best—and only—way to seal a bottle. Because of its cellular structure, cork can be easily compressed to fit the bottle neck and expands to form a tight seal. By far the classic choice, natural cork comprises about 80% of all wine closures, despite a spate of cork taint issues in the late 1980’s due to decreased manufacturing quality. Cork taint—a chemical contaminant that can make a wine smell like wet dog—only affects about 2% of all wine today, but is nonetheless something wine producers are keen to avoid. Most wines meant for long aging will be closed with a natural cork because of its natural ability to let the wine “breathe” slowly over time, but it is by no means an overall indicator of a wine’s quality.

Artificial Corks: New School

Most artificial corks are made from plastic polymers and are the preferred choice of wine producers whose wines are meant to be enjoyed young. With fewer pores to allow the same air exchange as natural cork, there is no risk of cork taint giving winemakers a more reliable—and cheaper—option for sealing off a bottle. Some artificial corks are also made from natural sugar cane, which eliminates what some experts say is a chemical taste that can be imparted with plastic corks. Many closures today are also some combination of both natural and artificial cork called colmated or agglomerated corks. Generally speaking, these enclosures suit wines that are meant to be drunk young and soon after bottling, while still allowing for the traditional bottle opening experience of pulling a cork.

Screw Tops: Too Cool for School

Once reserved for only low-end wines, screw caps can be found on wines ranging from widely-available Australian and New Zealand wines to micro-production Napa Valley reds. In use since 1964, screw tops were first introduced into the market to avoid cork taint contamination but have now gained more ubiquitous acceptance. In fact, it is more common to see a screw top on wines from Australia or New Zealand than an actual cork. Like artificial corks, these closures prevent oxygen from entering the bottle and ensure the wine maintains its crisp and fruit-forward flavors. White wines are the most frequently sealed with screw caps, but with technological improvements allowing for some air exchange, more and more age-worthy red wines are showing up with shiny metal tops as well.

Glass Tops: Beauty School

Slower to gain traction in the wine stopper world but nonetheless a promising, and growing alternative, is the glass wine closure. While more expensive, and requiring more tinkering on the wine bottling line, this closure is consistent and reliable with respect to wine maturation. Cork taint is a non-issue as the glass ensures the wine’s aromatic and phenolic characteristics are maintained. In addition, the seamless glass aesthetic is decidedly elegant and some producers have marketed their glass enclosure wines as “lifestyle” wines. The message has been successful—glass-capped beauties are becoming more and more common, now showing up in France, Germany, Australia, and California.

Ultimately, what’s in the bottle is the most important factor in a wine, so let’s not judge a wine by its closure. Cheers to cork—natural, artificial, metal, or glass—dorks everywhere!

So, what’s your take on corks? Give me a shout out and let’s discuss! Contact me at, or visit, Instagram (@thevinicola), or Facebook (theViniCola). Also known as the "Wine Evangelist," Erlinda A. Doherty, CSW, WSET Level 3, thinks screw tops are people, too.



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