Explore the enduring appeal of natural cork. Why do we love it? It’s sustainable, symbolic, and keeps your wine evolving gracefully in the bottle.

We don’t think about them often, but we sure miss them when they’re not there. Natural corks are part of the wine ritual, especially in restaurants. A server presents the chosen bottle and deftly uncorks it tableside with a handy three-step wine key. Then, they give us the cork to… see? Smell? Taste it with the tip of the tongue? Who knows[i]. But fancy restaurants even have a small plate—sometimes silver—specifically for this purpose.

Rest of the time? You don’t give corks a second thought. That’s fine. Normal, even. However, as casual as we like to get here about wine, I’m a geek. So, let’s talk about corks for a bit.

Natural Cork: The Most Widespread Wine Stopper

When we think about our bottle’s wine closure, natural cork is usually the first thing we imagine. There are no detailed statistics on the subject, but estimates suggest that 70% of wineries in North America use cork in their bottles[ii]. Wineries worldwide prefer natural cork as their stopper, and I’ll be willing to bet most drinkers do as well.

That said, cork closures, as we think of them today, are relatively new, compared to how long wine has been around. Collective lore often credits a French monk for creating wine corks, but misinformation about his life is common[iii]: Dom Pérignon didn’t invent corks, no matter what you’ve heard.

Half harvested cork oak.

Brief History of Cork as Wine Closure

Ancient Romans—and Greeks before them—were already using cork to seal their wine amphorae. People used long before that, of course. Chinese fishermen were using it as floats for fishing nets five thousand years ago. We don’t know when people began using it as stoppers, but archeologists found cork-sealed vessels from 500 BCE.

Strangely, People largely discontinued this practice in the Dark Ages[iv]. Less strangely, they also stopped topping amphorae with oil to prevent oxidation. Yes, they really did that. And no, medieval Europe didn’t completely shy away from using oil. They used wooden stoppers wrapped in oil-soaked cloth to replace cork. And they continued to do so until Dom Pierre Pérignon, allegedly, created the cork stopper. This is, of course, not true. By the time our good monk became the steward of Saint-Pierre d’Hautvillers’ abbey in the late 1660s, where he supposedly created them, French winemakers had already been using cork stoppers for at least a decade or two.

Popularity grew, trade stabilized, and we’re still using cork to seal our bottles[v] today. Ah, but not all cork stoppers are created equal, are they?

Types of Cork Stoppers

Cork is the bark of the cork tree. Harvesters remove it by axe and then allow it to grow back. They return to collect bark again from the same tree after allowing for seven years of regeneration. From the bark, hands or machines punch cork stoppers into…

• Natural Cork. Workers sort barks by quality and thickness. They then drill, or punch, cork cylinders out of selected pieces of bark. That’s it: your basic stopper. Natural cork is the better alternative for long-term wine storage, but it’s also the most expensive.
• Agglomerated Cork. Workers grind leftover bark pieces—the ones from the process above—into a powder and glue them together into a cylinder. An economic alternative for wines meant to be drank within a year or so.
• Technical Cork Stoppers. So, you grab the above agglomerated cork[vi] and glue a disk of natural cork on each side. This technique gifts wine a few years in the bottle, allowing bottle-aging time of up to three years.
• Colmated Cork. To increase the quality of somewhat deficient corks, manufacturers fill the pores with cork dust. This improves the cork’s performance, allowing wines to age in the bottle for a couple of years.
• Multi-Piece Cork. Natural cork scraps aren’t always ground. If the pieces are good quality, but not thick enough, workers can glue them together into the proper shape.

Harvested cork bark drying. Workers, or machines, will punch cork cilindres out of them.

Cork is great because it’s porous and therefore allows for a little oxygen to get inside the bottle. Wine lives inside the bottle, and it needs to breathe to evolve. Of course, too much oxygen is detrimental, but no oxygen is worse.

It’s not all roses in cork-land, though. These stoppers… well… they’re natural, which means consistency goes out the window. Oxygen gets into bottles at dissimilar rates depending on the cork, and therefore each bottle evolves differently. You will, of course, get better results if you store your wine properly.

Then, there’s cork taint, which can cause you wine to be…

“Corked”, The Bane of Natural Cork

Furthermore, being natural, cork closures are vulnerable to outside contamination. Mold spores, present throughout most of the winemaking process—from collecting the bark for the corks, to storing them, to cleaning them, and even in oak barrels and other winemaking equipment—can create a chemical reaction we know as TCA, which is not unhealthy, but unfavorably changes the aromas and flavors of the wine into something close to wet cardboard. This cork taint happens to about 2%[vii] of bottles. This is what we call corked wine.

Cork taint and inconsistent evolution are the problems all other wine closures are trying to solve, but that’s a story for another day.

The Last Drop

Other wine closure alternatives, particularly screwcaps, are growing in popularity. However, natural cork still reigns, despite its drawbacks. I remember working as a server in a restaurant, and the front-of-the-house manager instructed us to discretely unscrew bottles and hide the cap quickly to avoid guests judging the wine or whoever picked it. Probably an exaggeration, but it’s hard to argue that the overall impression of screwcaps is that they’re cheap, and therefore so is the wine.

People seem to like natural cork best. I’m sure part of it has to do with tradition and the ritual of uncorking a bottle. Twisting the wrist just doesn’t hit the same.

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Footnotes

[i] I don’t mean to be patronizing. You probably know why they do it. First, to look at the cork to see if too much wine has penetrated. For young-ish wines, only the tip should be wine colored. More and you might be dealing with a faulty cork. And second, to smell it for defects: your first line of defense to see if it’s corked. Just… just don’t taste it.

[ii] Important: This isn’t saying 70% of wines use natural cork, just that wineries use them plenty. But the same wineries also use screw caps and other closures. Read a report on the subject here.

[iii] Dom Perignon is sometimes credited for creating sparkling wine, which is also not true.

[iv] Buckle-up. I’m about to go deep into medieval history here, but I’ll try to keep it short. The Romans had a network of roads facilitating commerce. When the Empire collapsed, road maintenance was disrupted, and therefore so was trade. This affected both the viticulture and cork industries. Furthermore, winemaking became a responsibility of the Catholic Church, which needed it for religious ceremonies. Trading for cork became even more complicated because most cork trees were–and are—found in the Iberian Peninsula, which was under Muslim rule at the time.

Not only there was no love lost between adherents to both religions, but alcohol was prohibited under Muslim law, so selling cork to be used in wine might’ve been seen as a religious crime. Cork, where available, was still used as wine closure. Elsewhere, they had to turn to other trees to make do.

[v] Incidentally, glass bottles also became popular to store wine in the mid 17^th Century.

[vi] Not exactly the same, as for this technique, densely packed agglomerated cork is needed.

[vii] Exact industry figures are hard to find, but it’s estimated that the number would be between 2% and 5%. However, in a lot of cases the taint is too slight for all but the most trained noses to detect it. The flavors of the wine would be muted, but if we have no experience with it, we are unlikely to detect it.

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Cover image: Natural cork used as bottle stopper. Photo by InsatiableVine.