Storage
Closures
The thing in the neck of the bottle decides how much oxygen reaches the wine, whether the bottle can lie down, and how likely it is that the wine is spoiled before you pour it. It decides almost nothing about quality.
A closure is an oxygen-transmission decision. Every one of them lets some oxygen through; they differ in how much and how consistently. That is why the arguments about them are arguments about the rate and character of development, not about whether development happens — and why the strongest claim anyone can honestly make for a closure is consistency rather than superiority.
The seven you will meet
Natural cork
Oxygen ingress: Low to moderate · Store on its side
A single punched cylinder of bark from the cork oak, used for wine bottles since the seventeenth century.
Cork is a closed-cell material of roughly forty million cells per cubic centimetre, each holding a gas mixture. Compressed into the neck it exerts constant outward pressure and seals; its cellular structure lets a small and variable quantity of oxygen through over time.
Does the wine age?
Yes, and it is the closure most long-lived wines are still bottled under. The variability that is a weakness for consistency is arguably a strength for complexity, though that argument is aesthetic rather than demonstrated.
On its side?
A cork that dries out shrinks and stops sealing. Lying the bottle down keeps the cork in contact with the wine and therefore damp. This matters over years rather than weeks — a bottle standing upright for a fortnight is in no danger.
Spoilage risk
The one genuine drawback. 2,4,6-trichloroanisole (TCA) can form in cork and produces a musty, wet-cardboard aroma at vanishingly low concentrations. Prevalence figures vary widely and come mostly from interested parties; the risk is real, has fallen substantially since the 1990s through better processing, and is not zero.
Opening and resealing
A corkscrew. Older and more fragile corks may need a two-pronged extractor instead. Push the cork back in the way it came out. It will not go back as far and does not need to.
Strengths
- A long track record under real cellar conditions, which no newer closure can yet match
- Renewable and biodegradable, harvested without felling the tree
- The cork oak landscapes of Iberia support high biodiversity and depend on the industry continuing
Weaknesses
- TCA taint, which affects individual bottles unpredictably
- Bottle-to-bottle variation in oxygen ingress, which means two bottles of the same wine can evolve differently
- Requires horizontal storage over the long term
Specifics
- Material (physical fact)
- Bark of Quercus suber, harvested roughly every nine years without harming the tree.
- Oxygen ingress (physical fact)
- Low to moderate, and variable between individual corks from the same batch.
Commonly found on: Fine wine intended for ageing; Traditional regions across Europe; Most wine above the everyday price point.
Technical and agglomerated cork
Oxygen ingress: Low · Store on its side
Cork granules bound together, sometimes with natural cork discs at the ends that meet the wine.
Granulated cork is washed, treated and bound under pressure. Because the granules can be processed in ways a whole cork cannot — including supercritical carbon dioxide extraction — TCA can be removed far more reliably than from a single punched cork.
Does the wine age?
Designed for the medium term rather than for decades, and manufacturers now sell grades with specified oxygen transmission rates for a given ageing window.
On its side?
Behaves like natural cork: the binder and the granules both dry out if the closure is not kept damp.
Spoilage risk
Substantially lower than natural cork, because the granules can be treated in bulk in ways a whole cork cannot.
Opening and resealing
A corkscrew. Agglomerated corks can crumble if the wine is much older than the closure was designed for. As natural cork.
Strengths
- Far more consistent oxygen ingress than natural cork
- Much lower taint risk
- Grades sold with a specified transmission rate, so a producer can match the closure to the wine
Weaknesses
- Not intended for very long ageing; the binder degrades over decades
- Carries the cultural signal of "cheap" that its performance does not justify
Specifics
- Taint mitigation (physical fact)
- Granulated cork can be treated with supercritical CO₂ extraction, which removes TCA far more effectively than any treatment for a whole cork.
Commonly found on: Mid-priced wine intended to be drunk within a few years; Increasingly, wines that would once have had natural cork.
Synthetic cork
Oxygen ingress: Moderate · Upright is fine
An extruded or moulded plastic cylinder shaped to behave like cork in a standard bottling line.
A polymer core with a denser skin, sized to compress into a standard neck. It exists mainly so a producer can change closure without changing equipment.
Does the wine age?
Poorly, and this is the honest weakness. Oxygen ingress is comparatively high and, in the earlier generations, rose over time as the material relaxed. A wine under synthetic cork should be treated as one to drink within a year or two.
On its side?
Plastic does not dry out, so there is no reason to keep it damp.
Spoilage risk
No cork-derived TCA. Some early synthetics contributed their own plastic aromas; the current generation largely does not.
Opening and resealing
A corkscrew, and they are notably stiff — a lever corkscrew is easier than a waiter’s friend. Difficult. Synthetic corks expand once removed and often will not go back in.
Strengths
- No cork taint
- Consistent between bottles
- Inexpensive and compatible with existing bottling lines
Weaknesses
- Higher oxygen ingress than any other closure here, so wine ages and tires faster
- Hard to remove and often impossible to replace
- Petroleum-derived, and recycling routes are limited
Specifics
- Oxygen ingress (physical fact)
- Higher than cork or screwcap, and in earlier generations increasing over the first year in bottle.
Commonly found on: Inexpensive wine intended for immediate drinking.
Screwcap
Oxygen ingress: Very low · Upright is fine
An aluminium cap with a liner that seals against the lip of the bottle. Standard in Australia and New Zealand, common everywhere.
The seal is made by the liner, not by the metal, and the liner is where the engineering is. A tin-faced liner is close to airtight; a saran-faced one admits a small, specified and very consistent quantity of oxygen. A producer chooses the liner to match the ageing the wine needs.
Does the wine age?
Yes. This is the misconception worth correcting directly: wine under screwcap ages, and the long-running Australian closure trials have followed the same wines under different closures for over two decades. What differs is the *rate* and the *character* of the development, because less oxygen crosses the seal. Some tasters prefer the result and some do not; that is a preference, not a defect.
On its side?
Nothing to keep damp. Upright storage is fine and arguably better, since it keeps wine off the liner.
Spoilage risk
No cork-derived TCA. It is worth being precise rather than absolute: TCA can reach wine by other routes — contaminated cellar timber, cardboard, cleaning agents — so "screwcap means never corked" overstates a real advantage.
Opening and resealing
Hold the cap and turn the bottle, not the other way round. The perforations break cleanly. The best of any closure. It goes back on properly and seals again.
Strengths
- Very consistent between bottles, which is its strongest genuine claim
- No cork-derived taint
- Reseals properly — a real advantage for anyone not finishing the bottle
- Requires no corkscrew
Weaknesses
- A very low oxygen ingress can allow reductive, struck-match or sulfurous characters to persist where cork would have dispersed them — which is why liner choice matters
- Carries a downmarket signal in some markets that has nothing to do with its performance
- Aluminium production is energy-intensive, though the cap is recyclable
Specifics
- Where the seal is (physical fact)
- In the liner, not the metal. Tin-faced liners are near-airtight; saran-faced liners admit a small, specified amount of oxygen.
- Ageing (physical fact)
- Wine under screwcap ages. Long-running comparative trials have tracked identical wines under different closures for more than twenty years.
Commonly found on: Almost all Australian and New Zealand wine, at every price; Increasingly common in Europe, including serious Riesling and Chablis.
Glass stopper
Oxygen ingress: Very low · Upright is fine
A moulded glass plug sealing against an inert polymer O-ring, held by a foil sleeve.
The glass itself is inert and does nothing; the O-ring makes the seal. Oxygen ingress is very low and highly consistent.
Does the wine age?
On the evidence available, comparably to a tight screwcap. It is a newer closure with a shorter track record than either cork or screwcap.
On its side?
Nothing dries out.
Spoilage risk
No cork-derived taint.
Opening and resealing
By hand, after breaking the foil seal. No tool needed. Excellent — it seats and seals again.
Strengths
- Reseals well
- No taint
- Opens without a corkscrew
- Visually distinctive
Weaknesses
- Expensive
- Heavier, which raises shipping emissions
- Shorter track record than cork or screwcap
Specifics
- What seals it (physical fact)
- The polymer O-ring, not the glass. The glass is inert and structural.
Commonly found on: Premium Austrian and German wine; A minority of producers elsewhere.
Crown cap
Oxygen ingress: Low · Upright is fine
The same closure a beer bottle uses, sealing against the lip with a crimped skirt and a liner.
A metal cap crimped over the lip, with a liner making the seal. Holds pressure well and is inexpensive.
Does the wine age?
Used mostly for wine not intended for long ageing, and for the second fermentation of traditional-method sparkling wine before disgorgement — where it may sit for years.
On its side?
Nothing to keep damp, and sparkling wine under crown cap is normally stored horizontally for other reasons.
Spoilage risk
No cork-derived taint.
Opening and resealing
A bottle opener. Not without a capper, though sprung bottle stoppers fit.
Strengths
- Holds pressure
- Very cheap and very consistent
- Standard for pét-nat and for sparkling wine during ageing
Weaknesses
- Needs an opener
- Does not reseal
- Reads as informal, which for pét-nat is the intention
Specifics
- Sparkling wine (physical fact)
- Traditional-method sparkling wine spends its entire lees-ageing period under crown cap. The cork goes on only at disgorgement.
Commonly found on: Pétillant naturel; Traditional-method sparkling wine before disgorgement; Some low-intervention still wine.
Sparkling wine cork
Oxygen ingress: Low · Store on its side
A wide agglomerated cork with natural cork discs at the wine end, compressed into the neck and held by a wire cage.
It goes in as a cylinder roughly twice the neck diameter and is compressed. The familiar mushroom shape is the part outside the neck relaxing back; the part inside stays compressed against six atmospheres of pressure. The wire cage — the *muselet* — stops it leaving.
Does the wine age?
Yes. Vintage Champagne under its own cork ages for decades.
On its side?
Conventional practice, though the case is weaker than for still wine: the headspace in a sparkling bottle is saturated with carbon dioxide, which keeps the cork from drying as quickly. Horizontal storage remains the safe default.
Spoilage risk
Cork-derived TCA is possible, as with any cork.
Opening and resealing
Hold the cork, turn the bottle, and keep a thumb over the top throughout. Point it away from people. The pressure inside is around six atmospheres — roughly three times a car tyre — and an escaping cork travels fast enough to cause serious eye injury. Not with the original cork, which will not go back. A sprung sparkling stopper is the answer.
Strengths
- Holds substantial pressure reliably
- Ages well
- The mushroom shape records how long the bottle has been closed
Weaknesses
- Cannot be replaced once removed
- Carries the same TCA risk as any cork
- Requires careful opening
Specifics
- Pressure (physical fact)
- A bottle of Champagne holds roughly six atmospheres, about three times the pressure in a car tyre.
- Safety (safety)
- Keep a thumb on the cork from the moment the cage is loosened and point the bottle away from people. Ophthalmic literature records serious eye injuries from Champagne corks.
Commonly found on: Champagne and all traditional-method sparkling wine after disgorgement; Most tank-method sparkling wine.
Claims that circulate and do not hold
These are published rather than quietly omitted. A reader will meet all five, and a page that simply states the correct position without naming the incorrect one leaves someone who already believes the wrong thing with no way to notice.
“A screwcap means the wine is cheap.”
It means the producer chose a closure. Australia and New Zealand moved to screwcap at every price point in the early 2000s, and some of the most expensive wine either country makes is under one. In Europe the signal persists commercially and carries no information about the wine.
“Wine under screwcap cannot age.”
It ages. Comparative trials have followed identical wines under different closures for more than twenty years. What changes is the rate and the character of development, because less oxygen crosses the seal — some tasters prefer the outcome and some do not. That is a preference, not a limitation.
“A screwcap means the wine can never be corked.”
Almost right, and worth stating precisely. Screwcap eliminates *cork-derived* TCA, which is the overwhelming majority of cases. TCA can also reach wine through contaminated cellar timber, cardboard or cleaning agents, so the risk is greatly reduced rather than abolished.
“All wine must be stored on its side.”
The rule exists to keep a cork damp so it does not shrink. It applies to cork and to nothing else — screwcap, glass stopper, synthetic cork and crown cap have nothing to dry out, and upright storage is fine. It also applies over years rather than weeks: a corked bottle standing upright for a fortnight is in no danger.
“A dry or crumbly cork means the wine is ruined.”
It means the cork is old or was stored upright, and it makes opening awkward. Whether the wine is affected depends on whether the seal actually failed, which shows as seepage down the neck or an unusually low fill level. A crumbly cork on a sound-looking bottle is often just a crumbly cork.
“A synthetic cork is just as good as a natural one.”
Not for keeping. Synthetic closures admit more oxygen than any other type here, and earlier generations admitted increasing amounts over the first year. A wine under synthetic cork should be drunk within a year or two rather than cellared.
Where this matters
- Storing wine — the closure decides whether the bottle needs to lie down and how much the humidity matters.
- Ageing — oxygen ingress is one of the four things that determine how a wine develops, and the only one you can read off the bottle.
- Faults — cork taint is the fault most people can name and the one the closure choice most directly addresses.
- How long will this keep? — resealing behaviour differs sharply, and a sparkling cork will not go back in.