Wine corks
Image credit: Sam Howzit [CC BY 2.0], via Flickr

When I was in high school—this was, you know, a long time ago, back when cameras used film—I had a darkroom in the basement. Because I didn’t do a large quantity of film processing, one of my biggest concerns was that the expensive chemicals would go bad before I had a chance to use them. Since it is primarily exposure to oxygen that damages photographic chemicals, I stored them in air-evacuation containers, which are basically plastic bags inside boxes. As you drain out the chemical through a special spout that sticks out through the box, the bag shrinks, thus making sure no air gets in. This solution is simple, elegant, and effective.

The very same laws of chemistry apply to wines, and that is why wine is sometimes sold “by the box” in air-evacuation containers. It keeps wine fresher longer, and is often less expensive than bottled wine. What’s not to like? And yet, boxed wine is routinely ridiculed as low-class. Everyone knows that any decent wine will be stored in a corked bottle. It’s just The Way Things Are. It’s not about oxidation, it’s about perception. You have to do things right. Buying wine in a box is tantamount to buying wine with a screw cap. It’s an indication of poor quality. Or is it?

Over the past decade or two, it’s become increasingly common to see wine bottles stoppered with a “cork” made out of plastic. I found that odd at first, though I eventually came to accept it as more or less normal. But I still find myself wincing at the notion of screw caps, which themselves are appearing on more and more “respectable” wines. I’ve discovered that there is in fact an intense debate raging in the wine industry over the best method of sealing a wine bottle, and the pros and cons of each approach are much different from what I would have thought. Here for your enlightenment and entertainment is a summary of the major positions in the debate.

Cork: the traditional approach

  • Pros: Cork has a long history; it has been used as the sealing method of choice for over 400 years. Cork stoppers, because they are such a pain to remove, implicitly signal quality. When they work, they work well. They’re a renewable resource (the trees are not killed when the bark is stripped to make cork). They make a satisfying “pop” when removed from the bottle. They’re readily biodegradable. And they support an entire industry of corkscrews and other cork-removal products.
  • Cons: Corks often go bad. Estimates vary widely, but many bottles of wine are ruined due to corks that are tainted, ill-fitting, or deteriorated. (Depending on which figures you believe, as little as 1% or as much as 20% of all wine sold is “corked,” which is to say, damaged by a problematic cork.) Corks can be difficult to remove, and sometimes break off into the bottle. The world’s cork supplies are nearly maxed out, so cork prices are increasing.

Plastic: the new cork

  • Pros: Plastic is immune to cork taint, so wine is much less likely to spoil. Plastic corks can be made more cheaply, and with much more precision, than cork stoppers. Depending on the vintner’s tastes, plastic corks can be made to look very similar to natural corks, or be molded in any imaginable designer color. They’re recyclable. And the same cork-removal equipment (along with its obligatory “pop” sound) can be used.
  • Cons: If the trees used to produce cork are no longer used for that purpose, they may be cut down to make space for more lucrative crops, thus endangering the habitat of various kinds of wildlife and altering the local ecosystem in unpredictable ways. If not recycled, plastic corks also pose a more direct threat to the environment. Some wine experts claim plastic corks unfavorably affect the flavor of wine. On the other hand, they don’t hold the aroma of wine well, making the ritual of cork-sniffing unsatisfying. The plastic may not retain its elasticity well over time, making it unsuitable for wines meant to age for decades. And most importantly, it’s just not right.

Screw caps: a strange twist

  • Pros: Screw caps, like plastic corks, avoid problems of cork taint, and yet unlike plastic are much less likely to affect wine’s flavor or lose their effectiveness over time. They are less expensive than natural or plastic corks. And they can be removed without any special equipment.
  • Cons: As with plastic corks, screw caps imply environmental issues associated with the loss of cork farming. Cork sniffing, of course, is right out. And again, most importantly, it’s just not right. You shouldn’t be able to get at your wine as easily as you get at your cola.

Crown seals: good enough for beer

  • Pros: Crown seals (the type of bottle cap used on most beer bottles) are basically screw caps without the screw part, so they have all the same advantages except ease of removal.
  • Cons: The downsides of crown seals are the same as for screw caps, with the additional issue of needing a bottle opener. Oh, and resealing a partially used bottle requires a different stopper or cap.

Of these, crown seals came on the scene most recently and so far appear with the least frequency. Meanwhile, air-evacuation containers, which were previously used only for the cheapest wines, now sometimes hold fancier varieties. (No one seriously proposes distributing high-end wines in air-evacuation containers, since bottles are more durable and less likely to leak over a period of many years.) There are, I’m sure, any number of other equally sensible alternatives out there. But the habit of associating cork with quality is still hard to break.

Note: This is an updated version of an article that originally appeared on Interesting Thing of the Day on September 22, 2003, and again in a slightly revised form on December 26, 2004.