Caps, Corks, and More: Everything You Need to Know About Wine Bottle Closures

Wine Closures

No wine-related topic garners more debate than that of bottle closures. Although corks and caps are most common, a handful of methods are used to seal up your favorite bottles, and endless questions continue to circulate around these stoppers. Each type of wine closure brings its own set of pros and cons to the table, so knowing the differences amongst these stoppers is key. We’re breaking down everything you need to know about wine closures, from cap to cork and all of the options in between. Simply pop a bottle and read on!

Cork
Cork capsules are by far the world’s most recognized and widely-used style of wine closure. The practice of sealing off bottles with corks dates back to ancient times, though the modern-day cork closure that we recognize today first became popular during the 1700s. Cork comes from the bark of the quercus suber tree, otherwise known as the cork oak tree. Most of these trees are located in the Iberian Peninsula (Portugal and Spain), making these two nations the world’s most important producers of wine corks. Wine corks are produced from the bark of these trees, which renew themselves every nine years. This means that a cork tree can only be harvested approximately once per decade! However, these hearty trees can live up to 200 years, so in theory, one single cork tree can sustainably provide wine closures for thousands of wine bottles over the course of its lifetime.

corks

In addition to the festive pop that comes from opening a bottle closed with cork (especially those with bubbles in them), cork closures are one of the best choices for sealing up wines destined for lengthy periods of time in the cellar. The natural elasticity and tiny pores within cork closures allow small amounts of oxygen to interact with a wine over time, which allows it to develop, change, and age gracefully. The biggest con to using cork closures is that they are susceptible to the cork taint 2,4,6-trichloroanisole, otherwise known as TCA (this is where the term ‘corked wine’ comes from). Corked wines often give off aromas of wet cardboard, chlorine, or musty basement. Corks can also become fragile over time, and if they dry out too much, the closure will crumble upon opening. However, this can usually be avoided by aging wines in optimal ‘cellar-worthy’ conditions, which includes keeping them on their sides in dark, cool, and humid locations.

Synthetic/Plant-Based Cork
To combat the potential risk of TCA, many producers have turned to the use of synthetic or plant-based corks. Synthetic corks are usually made from melted down polyethylene, which is then turned into a foam-like porous closure that imitates the elasticity of natural cork. Plant-based stoppers are usually produced from bio-polyethylene, which are made from natural and sustainable materials. The most popular synthetic cork closure brand on the market today is Nomacorc/PlantCorc, both of which promise to preserve wine for up to 25 years without the risk of cork taint. These closures are also recyclable and create minimal waste during their production. Additionally, Nomacorc/PlantCorc closures don’t dry out, so bottles aging under them do not need to be stored on their sides. Synthetic corks are also usually the cheapest option (over regular cork/screw caps) for winemakers to use, which adds to their appeal.

corks
Although these alternative corks sound like the perfect alternative, there are still a few flaws. Synthetic corks made from plastics (not plant-based) are not biodegradable, which make them a less-sustainable option for the environment. Synthetic corks can also be tricky to remove from bottles, and once they are pulled, pushing them back into a bottle to reseal it can be difficult. Plant-based closures are a bit more malleable and provide the best happy-medium, however, these closures tend to be pricier than synthetic corks/regular corks.

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Screw Caps
The long-standing debate still remains: which is better, cork or screw cap? The answer is … still complicated. As with corks, screw caps provide many pros and cons in the realm of bottle closures. On the positive side of things, wines bottled under screw caps almost never experience TCA, unless the winery’s oak barrels somehow become infected with the taint -- though that’s a whole ‘nother beast to break down.

Additionally, screw caps are usually cheaper and almost always easier to open than cork closures, though when it comes to ageworthiness, the debate still stands. Many believe that the oxygen-free environment that screw cap wines live under actually gives them a longer life span, though the counterargument to this point of view is that said lack of oxygen can leave these wines prone to reduction (excessive sulfur dioxide levels which lead to egg/nail polish remover smells in wine). However, the biggest factor in this debate is that not many collectors/wineries have ample experience with extensively aging wines under screw craps, so the data is hard to analyze.

Another con with screw caps is that they are generally made from aluminum, much of which isn’t biodegradable, which makes these closures one of the less sustainable options of the bunch. However, in terms of convenience, screw caps’ ability to pop on the fly without the need for a corkscrew makes them a top choice for immediate drinking.

Crown Cap
Though not as common as cork closures, crown caps (most commonly seen on beer bottles) are often found atop fizzy bottles of sparkling wine, particularly pét-nats. Sparkling wines produced via the méthode traditional (think Champagne and Cava, not pét-nat) are usually sealed with these crown closures whilst undergoing their primary fermentation, as these stoppers have a high ability to withstand excessive levels of pressure in bottle. Upon disgorgement, these crown caps are removed and replaced with cork and wire cages. However, most pét-nats don’t go through the disgorgement process and are simply released once their primary fermentation is done in bottle. Since there is no need to disgorge and reseal, many bottles are simply released and sold with their crown cap closure.

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Wax Top
Nothing sends wine drinkers into a state of confusion like wax-sealed wine bottles. Though fear not! Most wax seals are simply used for aesthetic purposes, and no additional measures need to be taken to open these bottles. Simply push your corkscrew into the top of the bottle as you would a normal cork, twist, and get to popping. The top of the wax seal should generally lift off in one solid piece. Still not sure what we mean? Check out this video of our co-founder Dustin Wilson MS to see how it’s done!