Why Most Wines Are Closed Wrong

The Mismatch Between Wine Style, Oxygen, and Decision-Making

The moment a bottle is sealed, a decision has already been made.

Not consciously, in most cases. That is the problem.

The closure was chosen weeks or months earlier, often by someone other than the winemaker, for reasons that had little to do with how the wine was built or what it would need to become. It was chosen because it is what the domaine has always used. Because it photographs well. Because the importer expects it. Because tradition does not ask questions.

And so the wine spends the next two, five, or twenty years inside a container chosen without asking the one question that actually matters:

What does this wine need after bottling?

The answer to that question is not the same for every wine. It is not even close to the same. And the fact that most of the industry behaves as though it were is why most wines are closed wrong.

Closure is a Control System, not a Formality

There is a persistent belief in wine that closures are neutral, that they seal the bottle and step aside. They do not.

Every closure imposes a trajectory.

What governs that trajectory is oxygen transmission rate, or OTR: the rate at which oxygen moves through the closure material into the bottle after sealing. This is not a trivial variable. Post-bottling oxygen is one of the primary drivers of chemical evolution in wine. It influences tannin polymerization, aromatic transformation, and the pace at which primary fruit compounds give way to secondary and tertiary development.

Natural cork introduces OTR variance of somewhere between 0.5 and 2.5 mg of oxygen per year per closure, and that range exists within a single production batch, not across different suppliers. Screwcap closures with Saranex liners transmit close to zero oxygen. Technical closures like Diam or Nomacorc can be engineered to specific OTR targets and replicate that target across hundreds of thousands of closures.

None of these is a neutral position. Each one pushes the wine in a specific direction. The question is whether that direction was chosen or simply inherited.

The Two Classic Misalignments

Understanding where closure choice goes wrong requires looking at the two most common failure modes, not as abstract categories, but as sensory outcomes.

The first is the structured red under a near zero oxygen environment.

Consider a wine built for aging: high phenolic concentration, firm tannins, not yet resolved. A Barolo, a Ribera del Duero, a serious Bordeaux-style blend. This wine was designed to evolve. The tannins are not there to be aggressive. They are there to polymerize over time, to soften and integrate, to become something the wine is not at bottling. That process is oxygen-dependent.

Seal it under a screwcap with a Saranex liner, and what happens? The wine does not progress the way it was designed to. Tannins remain harder for longer. The aromatic development stalls at an earlier stage. In certain conditions, particularly where sulfur management was not precisely calibrated for a low oxygen environment, the wine begins to develop reductive off notes. Hydrogen sulfide. Dimethyl sulfide. Compounds that emerge when sulfur chemistry is not metabolized out through the micro oxidation that the closure has blocked.

The wine tastes closed. Severe. Resistant. Not because something went wrong, but because the closure made the wrong kind of correct decision.

The second failure runs in the opposite direction.

An aromatic white wine, Riesling, Grüner Veltliner, Sauvignon Blanc from a cool climate, depends almost entirely on the integrity of its volatile aromatic compounds. Thiols, esters, terpenes: these are fragile, reactive molecules. Their presence is the wine. Their precision defines quality.

Seal this under natural cork. Most bottles will be fine. Some will lose aromatic intensity faster than others. Some will show the quiet, papery suppression of low level cork taint, not the full wet cardboard assault of severe TCA, but the subtler damage that simply removes the top register of the wine's aromatics without announcing itself. A few will be fully tainted. A few will oxidize prematurely.

What the producer has created is not a wine. It is a distribution. Bottle-to-bottle variation that should not exist. And in sensory terms, the average bottle of that wine will smell like less than what was made.

TCA: The Fault that does not Announce Itself

Cork taint gets discussed at its extremes. The obvious cases, musty, wet cardboard, damp basement, are easy to identify and set aside. They represent a small fraction of the actual problem.

The more significant issue is sub threshold TCA: concentrations low enough that the contamination is not consciously perceived, but high enough to cause measurable suppression of other aroma compounds.

The mechanism is neurological. TCA, 2,4,6 trichloroanisole, binds to TRPA1 ion channels in the olfactory epithelium, suppressing the calcium signaling that underlies normal olfactory transduction. At sub-threshold concentrations, the wine does not smell tainted. It simply smells less. The volatile aromatic compounds are present in the glass. The olfactory system is less equipped to detect them.

This means wines dismissed as average, flat, or uninspiring may simply be compromised. Their identity has been partially erased by a contamination that left no obvious trace.

From an educational or evaluative standpoint, this is a serious problem. You are not assessing the wine. You are assessing what remains after something was taken from it, and because the taking was invisible, you have no way of knowing.

Reduction is a Signal, not a Verdict

The opposite failure, reductive character under low oxygen closures, is frequently misread, and the misreading matters.

Reduction in wine is the accumulation of sulfur-containing volatile compounds: hydrogen sulfide, methyl mercaptan, dimethyl sulfide, and related molecules. These emerge when sulfur chemistry in the wine, residual from fermentation, from additions, from yeast metabolism, does not have access to the low level oxygen exposure required to metabolize or bind out.

Under screwcap, in a wine that was not prepared for that environment, these compounds concentrate. The wine smells closed, struck, sometimes aggressively sulfurous.

The closure is not the cause. It is the mirror.

Reduction tells you that the winemaking was not calibrated for the vessel it was placed into. Free SO2 levels, total sulfur compounds, dissolved oxygen at bottling, yeast strain, all of these interact with the post bottling oxygen environment. When the closure was chosen without factoring in those parameters, reduction is the result.

Blaming the screwcap for the reduction is like blaming a sealed room for the quality of its air. The room did not put the compounds there. It just stopped them from escaping.

The Prestige Contradiction

One of the most revealing contradictions in modern winemaking is the gap between process precision and closure choice.

The same producer who manages dissolved oxygen levels to fractions of a milligram per liter during aging, who chooses inert gas blanketing, tests for oxygen ingress at every transfer, and times racking decisions around oxidation thresholds, will then accept OTR variance in the order of hundreds of percent at the bottle.

Not because they do not understand the problem. Many do.

Because cork signals quality. Because the ritual of extraction is part of the product. Because removing that ritual risks a perception shift that the market may not have asked for.

This is a legitimate business consideration. But it should not be confused with a technical one. If a producer chooses cork for cultural reasons while understanding the OTR variability it introduces, that is a defensible position. What is not defensible is the pretense that cork is technically superior for a given wine when it is not.

The two conversations need to stay distinct: what is right for the wine, and what is right for the market. Most of the time, they are conflated, and the wine pays for it.

The Middle Ground: Technical Closures and What They Represent

The emergence of technical closures over the past two decades represents something more significant than a product category. It represents the industry beginning to treat closure as a technical decision.

Diam closures are produced from granulated cork that has been treated with a supercritical CO2 extraction process to remove TCA and related contaminants. They are then re-engineered with binding agents and compressed to specific density targets, allowing OTR to be adjusted at production. The result is a closure that retains the physical ritual of cork, the extraction, the pop, the cork in the hand, while offering contamination-free, reproducible oxygen transmission.

Nomacorc and similar synthetic technical closures work differently: they are extruded polymer closures that can be engineered to precise OTR specifications, often with very low batch-to-batch variance. They sacrifice the sensory and cultural experience of natural cork entirely, but offer the most controllable oxygen environment of any non-metallic closure.

Neither is universally correct. But both represent a shift in the logic of the decision, from what looks right to what performs right for a specific wine. That shift is worth recognizing, because it is not yet the industry norm.

Consistency is not a Compromise

There is a version of the cork defense that goes something like this: variation is interesting. No two bottles should be exactly the same. The unpredictability is part of the experience.

This argument is more romantic than rigorous.

In sensory terms, consistency is not the enemy of complexity. A wine that shows identically across bottles, that delivers the same aromatic register, the same structural development, the same expression of place, is not a lesser wine. It is a wine that can actually be evaluated. Taught. Discussed with precision.

When bottles of the same wine diverge significantly under cork, you are no longer tasting the wine. You are tasting a range of possible outcomes. That range may include beautiful bottles. It will also include compromised ones. And the drinker has no way of knowing which they have until they open it.

For educators, this creates noise. For consumers, it creates confusion. For producers, it creates reputation risk that has nothing to do with their winemaking decisions and everything to do with a sealing material they accepted without scrutiny.

Screwcap closures resolved this for many categories of wine. Not because they are superior in every context, but because they removed randomness from the equation. What you taste is what was made. That is not a small thing.

Closure is Part of Winemaking

This is the core of the argument, stated plainly:

Closure is not what happens after the wine is finished. It is the last winemaking decision, and it should be treated as such.

The closure decision belongs alongside harvest timing, fermentation management, aging duration, and sulfur regime. Not as an afterthought. As a continuation of the same logic that governed all those earlier choices, the logic of what this specific wine needs to become what it was designed to be.

Choosing a closure without reference to the wine's phenolic structure, its sulfur chemistry, its aromatic profile, and its intended development trajectory is not a neutral act. It is a choice made in ignorance of the consequences. And those consequences unfold slowly, invisibly, bottle by bottle, over the entire life of the wine.

Some wines need oxygen. Some need protection. Some need standardized, reproducible evolution across a large production run. Some need the ceremony. The decision should start with the wine, and work outward, not start with convention and work backward toward justification.

What You Can Do With This

The practical application is straightforward, if demanding.

Taste for closure. Compare the same wine across different sealing systems, ideally from the same vintage. Compare bottles from the same case opened at different intervals. Look for what is consistent and what is variable. Train yourself to identify the quiet suppression of sub-threshold TCA, the reductive flatness of sulfur accumulation, and the premature aromatic evolution of a wine that received more oxygen than it needed.

This is not theoretical work. It is observable. Once you begin to perceive the closure in the glass, not as a given, but as a variable that shaped what you are experiencing, the evaluation of wine changes fundamentally.

You are no longer asking only: what is this wine? You begin asking: what was it meant to be? And what stood between the two?

That question is not academic. It is how you start reading wine correctly.

About the Author

Sébastien Gavillet is COO of Wine Aromas - Le Nez du Vin. A renowned wine and whisky expert, winemaker, and distiller, Sébastien has been working with Le Nez du Vin for over 25 years. He is the author of Discovering and Mastering Single Malt Scotch Whisky and the International Whisky Guide series. He serves as a panel chair and examiner for The Council of Whiskey Masters, shaping global tasting standards and mentoring the next generation of spirits professionals.