I came back from a tasting today (the always excellent Central Coast Wine Classic) having again had my third discussion in a week with a consumer who was confused as to why we bottle some of our wines in Stelvin screwcaps, and others in cork. She asked if it was because the wines in screwcap were less expensive than those in cork (they weren't). We do our best to match up the wine with the closure that best allows it to age and evolve gracefully, and the answer is not the same for all wines, any more than a one-size-fits all prescription for winemaking would be. Tell a winemaker that he must choose either 100% barrels or 100% stainless steel tanks for everything in his cellar, and you'd have a revolt. And yet most accept such a prescription for sealing their wines without question.
I guess I can see how consumers would find this difficult to understand; most of the coverage of alternative closures is terribly reductive, either taking the position that anyone who stuffs a piece of tree bark into a bottle of wine deserves the contamination they're likely to get, or in talking in mushy language about the romance of opening a cork-finished bottle of wine. Probably the most public debate of this sort was played out in the March 15, 2005 issue of the Wine Spectator, where James Laube and James Suckling shared cover space with dueling articles entitled "Why I Hate Cork" and "Why I Love Cork".
It is undeniable that a percentage of all natural corks are tainted by TCA, a chlorine compound that makes the cork (and any wine in contact with it) smell and taste musty. Industry estimates range from 3% to as high as 10%. Even at 3%, this is a terribly large number of bottles that are ruined each year. For a winery of our size (our production of about 16,000 cases per year) this would mean that we'd send out over 5000 bottles that would be compromised. If we were lucky, the consumer would recognize that this bottle was corky and would request a replacement. If we're unlucky, the consumer just decides that he must not like Tablas Creek (or at least that particular bottling). It's easy to see why so many winemakers are passionate advocates of alternative closures.
At Tablas Creek, we have bottled samples of the same wines, finished in both cork and screwcap, since 2002. We have tracked their evolution to get some of our own impressions of what the various impacts of both options are. When we taste the wines, we do it blind, and ask ourselves (and anyone who joins us for these tastings) to describe what we taste. Matt Kramer included his experience in such a tasting in a thoughtful piece in the Wine Spectator in August 2004.
We (and everyone who's joined us) describe consistent differences between the cork-finished and screwcapped wines, and have noted these differences as early as 3 months after bottling. Wines bottled under screwcaps taste fresher, higher in acid, younger, tighter, and more mineral. Wines bottled under cork taste softer, sweeter, richer, more open, and more evolved. Which is better is not a simple question, and it depends on what we want out of the wine. For an aromatic white, or for our Rose, we like the brightness and freshness that the screwcap provides, and feel that the screwcap will have the additional benefit of keeping these wines (which are typically meant to be enjoyed young) tasting youthful longer. But those same characteristics do not benefit most of our reds, and they do not benefit our Roussanne-based whites, all of which we want to develop that softness and sweetness that time brings to wines meant to age.
There is logic to this. Corks come from the bark of cork oaks, and have a flavor (if untainted) similar to gentle oak from a barrel. In addition, they provide a measure of oxygen exchange with the wine (even if they provide a perfect seal between the wine and the outside air, corks contain oxygen in their pores and share that with the wine). Screwcaps provide a better seal, but don't provide either the flavor exchange or the oxygen exchange that a cork does. (New models of screwcap allow a tiny oxygen exchange with the air outside, but are new enough that we haven't felt comfortable experimenting yet.)
So, next time you hear a winery declare that they've switched entirely to screwcap, or a writer rhapsodize the ceremony of opening a cork-finished bottle, I hope you resist the suggestion that things are so simple. Rarely in life do either of two options, each with passionate advocates, have a monopoly on the truth. The debate between cork advocates and screwcap advocates is no different.