Everything to know about wine closures

Introduction to wine closures

Wine closures are a vital part of every wine bottle, serving as the guardian of the wine’s quality, flavor, and aging potential. The choice of wine closure, whether it’s natural cork, screw caps, crown caps, or other alternatives, can make a significant difference in how a wine develops over time. Wine producers must carefully consider which closure will provide the perfect seal for their specific wine, as this decision impacts everything from the prevention of cork taint to the wine’s ability to age gracefully.

In recent years, the market for wine bottle closures has expanded, with innovative alternatives gaining traction thanks to their cost-effectiveness, reliability, and resistance to common issues like cork taint. As the industry evolves, understanding the strengths and challenges of each closure type is essential for producers aiming to deliver the highest quality wine inside every bottle.

Many materials are available for sealing a bottle of wine, each with its own pros and cons. From natural cork to synthetic cork, aluminum composite to plastic, and even wax seals, there are plenty of options to choose from. In this article, we’ll explore the various materials used in wine sealing and packaging so you can make an informed decision when selecting the best option for your winery. Having knowledge of different closure options and their properties is crucial for making informed decisions that align with your brand and winemaking goals.

Corks

The use of cork as a stopper for wine bottles dates back to at least Roman times. Cork is derived from the bark of cork oak trees which grow primarily in Portugal and Spain. The bark is harvested every nine years without damaging or killing the tree. After harvesting, the cork undergoes manufacture through industrial processes, including boiling to soften it and preparing it for further shaping. It is then boiled to soften it before being cut into strips that can be punched into discs known as corks, with each disc carefully shaped to form the proper form needed to fit wine bottles securely.

[fs-toc-omit]History of corks

The use of cork as a stopper for wine bottles dates back to at least Roman times. Cork is derived from the bark of cork oak trees which grow primarily in Portugal and Spain. The bark is harvested every nine years without damaging or killing the tree. It is then boiled to soften it before being cut into strips that can be punched into discs known as corks.

[fs-toc-omit]Traditional types of corks

Three main types of wine corks are used in winemaking: natural cork, synthetic cork, and composite cork.

Natural corks are made from 100% natural cork oak tree bark. They are considered superior for their ability to age wines properly over time due to their porous nature, which allows oxygen exchange between the bottle and the atmosphere. However, a bad thing associated with natural corks is cork taint, a fault that can cause moldy or off aromas in wine.
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Synthetic corks are made from polyethylene plastic or rubber compounds that mimic natural cork but do not allow oxygen exchange. Hence, they are better suited for cheaper wines that should be drunk within two years of purchase.
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Composite corks are a combination of both natural and synthetic materials designed to provide some oxygen exchange while still providing an effective seal against leakage.

Natural cork | Agglo cork | Colmated cork

[fs-toc-h3]Innovative corks

In recent years, two new types of corks have entered the market: DIAM and Nomacorc. Both represent a break from traditional cork closures, offering wineries unique benefits that can help them better protect their wines.
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DIAM is a type of cork made from natural cork granules that have been treated with a patented process to make them impermeable to oxygen. The result is a cork that is much more resistant to oxidation than traditional corks, allowing wines to stay fresher for longer periods of time. DIAM closures also improve the bottling process by providing greater consistency and reducing the risk of bottle variation.
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Nomacorc is a synthetic cork made from polyethylene foam. It’s designed to be completely impermeable to oxygen, making it ideal for long-term storage of wine. Additionally, it’s also highly resistant to taint compounds, which can give the wine an unpleasant musty odor or taste if present in high enough concentrations. Nomacorc closures streamline bottling by ensuring a reliable seal and efficient packaging.

DIAM | Nomacorc

Both DIAM and Nomacorc are much more sustainable than traditional cork due to their low environmental impact during production and manufacturing processes. For example, while natural cork requires harvesting bark from trees every 9-10 years, which can lead to deforestation if not managed properly, neither DIAM nor Nomacorc require any harvesting since they’re made from recycled materials or synthetic polymers, respectively. These innovative corks are also typically much less expensive than natural cork ones, down to a quarter of the price, making them extra appealing in an environment where recent inflation is a struggle.

[fs-toc-omit]How the choice of cork affects wine quality

When it comes to choosing a cork, there are a lot of options to consider! Natural corks, composite corks, synthetic corks, technical corks, Diams, and NomaCorcs all have their own advantages and disadvantages. For many wine lovers, the sensory experience of pulling a cork from a bottle, accompanied by the satisfying 'pop,' is an important and romantic part of enjoying wine. Using a corkscrew as the traditional tool for opening cork-sealed wine bottles adds to this tactile ritual. However, it is important to note that corks are only one way to close a wine bottle: screw caps, glass stoppers, and more innovative solutions are also available. Keep on reading to learn more about these other methods of sealing wine bottles.

One popular alternative to cork is screw caps or Stelvin closures. These metal lids are becoming increasingly popular due to their convenience and affordability. They provide a reliable seal that prevents oxygen from entering the bottle and spoiling the wine. Additionally, they can be easily opened and resealed if needed.

[fs-toc-h3]Agglomerated cork and its benefits

Agglomerated cork is a popular wine closure that combines natural cork particles with a binding agent to create a consistent and cost-effective solution. Unlike traditional corks, which are cut from a single piece of cork bark, agglomerated corks are formed by compressing small cork granules together. This process not only reduces the risk of cork taint but also ensures a more uniform quality from one closure to the next.

For wine producers, agglomerated cork offers excellent value, providing a similar appearance and tactile experience to natural corks at a lower cost. These closures are especially appealing for wines intended for early consumption, as they deliver reliable sealing performance while maintaining the traditional look that many consumers expect. In recent years, the use of agglomerated corks has grown, reflecting their benefits in quality, affordability, and visual appeal.

[fs-toc-h3]Screw caps

Screw caps have been used for centuries to seal food containers and other products. However, it wasn't until the 1950s that they began to be used for sealing wine bottles. The first commercial use was by Australian winemaker Penfolds Wines in 1957, who used Stelvin-type screw caps on their Grange Hermitage wines. Since then, many other wineries around the world have adopted screw cap closures for their wines.

[fs-toc-omit]History of screw caps

Screw caps have been used for centuries to seal food containers and other products. However, it wasn't until the 1950s that they began to be used for sealing wine bottles. The first commercial use was by Australian winemaker Penfolds Wines in 1957, who used Stelvin-type screw caps on their Grange Hermitage wines. Since then, many other wineries around the world have adopted screw cap closures for their wines.

[fs-toc-omit]Types of screwcaps

The Stelvin original is the most common type of screwcap used in the wine industry. It is a simple aluminum cap with a plastic liner that provides an airtight seal.
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The Stelvin LUX has a more sophisticated design, featuring a plastic outer shell and an inner lining made from food-grade silicone rubber. This type of cap provides an even tighter seal than the original version and gives the bottle a more luxurious look.
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The third type of screwcap is the Stelvin without knurling, which has no knurled edges or ridges on its surface. This type of cap is often used for sparkling wines because it helps maintain carbonation levels better than other caps.

Stelvin original | Stelvin LUX | Stelvin without knurling

[fs-toc-h3]WAK closure

A WAK closure is a type of screw cap used to seal wine bottles. It is made up of an aluminium cap with threads that fit the neck finish of the bottle and a liner made from plastic, cork, or other materials. The WAK closure combines traditional aesthetics with modern technology to provide a perfect seal that prevents any liquid leaking and keeps other flavors out of the wine. This ensures that the quality and taste of the wine remain intact until it is opened.

WAK closure, the next-gen screw cap for wine

[fs-toc-omit]Advantages of screw caps over cork stoppers

The primary advantage of using a screw cap closure is improved quality control and consistency. Unlike corks, which can vary significantly in terms of size and density, screw caps provide a consistent seal that prevents oxidation and spoilage due to cork taint. They are much easier to open than corks and don't require special tools or expertise. This makes them ideal for everyday wines that don't need to be aged for long periods of time.

[fs-toc-omit]How the choice of screw cap affects wine quality

The impact of different types of screw cap closures on wine’s taste and aging potential varies depending on several factors such as grape variety, vintage year, region/appellation, etc.

Overall, choosing which type of screwcap to use for your wine bottles depends on how long you plan on storing them before drinking them, as well as your desired level of quality and preservation. By understanding these factors and selecting the appropriate type of cap accordingly, you can ensure that your wine will remain at its best when enjoyed.

[fs-toc-h3]Glass stoppers

Vinolok is a revolutionary glass closure developed by Alcoa co, a German company, for use in wine and spirits bottles. It is also known as a “glass cork” and has become an early alternative to traditional cork closures. Vinolok closures are made of a recyclable and reusable material—glass. They come in different types, such as the screw cap, Vino-Seal, Zork, and others. Vino-Seal stoppers carry oxygen barrier properties that help preserve wine quality and can result in shorter cellar times.

Classic high-top Vinolok, a premium glass stopper for wine and spirits

[fs-toc-omit]Advantages over glass stoppers over cork or screw cap

The key advantages of Vinolok over other glass closures are its oxygen transmission rate, ease of use, reusability, and recyclability. The oxygen transmission rate is much lower than that of natural cork or synthetic corks, which makes it ideal for long-term storage of wines. Vinolok closures are also easy to use as they require no special tools or techniques for opening the bottle. They can be reused multiple times without any loss in quality or performance. Moreover, they are highly recyclable, making them an environmentally friendly option for packaging wine bottles.

Overall, glass wine stoppers offer an attractive way for wine brands to add an extra layer of luxury and sophistication to their products while conveying a premium sense that will appeal to customers looking for something special.

[fs-toc-h3]Wine capsules and naked corks

Wineries have several options for the protective sleeve that covers the cork and neck of a wine bottle, known as the capsule. The choice can impact the wine's protection, presentation, and cost.

[fs-toc-omit]Traditional capsule types

Traditionally, capsules are made from tin, poly laminate, or heat-shrink PVC.

Tin capsules are the most traditional choice, typically used for high-end wines. They provide an excellent barrier against air and mold on the cork, along with an attractive finish.

‍Poly laminate capsules offer a more modern look and are available in various colors and textures.

‍Heat-shrink PVC capsules also come in many colors and styles but don't offer the same protection against air or mold.

[fs-toc-omit]The "naked cork" trend

A recent trend is to forego the capsule altogether, leaving the "naked cork" exposed. This approach often features the brand's logo printed on the cork. This trend is more cost-effective and sustainable than traditional capsules and creates an eye-catching presentation for customers. However, it also carries potential risks, such as an increased chance of oxidation due to the cork's direct exposure to air.

Ultimately, wineries must weigh their options carefully. Factors to consider include the desired aesthetic, level of protection needed, compatibility with the bottle shape, and the balance between cost and quality. Whether they stick with traditional capsules or embrace the "naked cork" trend depends on their unique needs and brand identity.

Classic tin capsule hiding the cork below | Naked cork (can be branded — with a winery logo, for example)

[fs-toc-h3]Specialty wine closures

One of the oldest and most traditional solutions is the dipped wax method. This involves dipping the neck of a bottle in melted wax which seals it shut. The advantage of this method is that it can be done quickly and easily with minimal equipment or cost. However, it does not provide as much protection against oxidation as other methods, meaning that wines sealed with this method may not last as long over time.

Straight wax for a classic look | Dripping wax for a rustic or antique look | Angled wax for a modern look

Small wax buttons are another popular option for producers looking for an alternative to cork closures. These buttons are placed on top of the cork before sealing the bottle, providing an additional layer of protection against oxidation and preserving the wine's flavor for longer periods of time. The downside to this method is that it requires more time and effort than other solutions, making it less appealing for some producers who are looking for a quick solution.

Lightly dipped wax | Wax button at the top of cork

Bartop (t-top) cork stoppers are a type of closure used to seal bottles, typically for wine, liquor and spirits. They are made from natural or colmated cork stoppers with a wooden, plastic or other material capsule applied on top. These stoppers provide a tight seal that keeps the contents of the bottle fresh and prevents leakage. Bartop corks are ideal for short-term storage and consumption of drinks, as they can be easily reclosed after opening.

Plastic bartop (t-top) cork stopper

[fs-toc-h3]Sparkling wine closures

Sparkling wines, like Champagne and Prosecco, are defined by their fizz. But that signature effervescence creates immense pressure within the bottle, often up to 90 psi (pounds per square inch), which is three times the pressure of a car tire. To contain this force, specialized closures are required to ensure safety and quality.

[fs-toc-omit]The traditional cork and muselet

The most iconic closure is, of course, the mushroom-shaped cork. Traditional sparkling wine corks are crafted to be significantly thicker and more elastic than their still wine counterparts. Before insertion, they are cylindrical; once forced into the bottle neck, they expand to create a tight, pressure-resistant seal.

However, the cork alone isn't enough to fight the pressure. It must be secured by a wire cage known as a muselet (or muzzle). This wire harness sits over the cork and is twisted tight under the bottle's lip to prevent the cork from popping out prematurely. Often, a small metal disc called a cap or hood sits between the top of the cork and the wire cage, providing a stable surface for the wire to grip and often displaying the winery's emblem.

[fs-toc-omit]Alternative sealing methods

While the cork-and-cage method is the standard for the final product, it isn't the only way to seal bubbles.
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Crown caps: Similar to those found on beer bottles, crown caps provide a secure, cost-effective solution. They are widely used during the "secondary fermentation" phase (aging on lees) because they offer an excellent seal against oxygen and are easy to remove during disgorgement.
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Technical corks: Many modern producers use agglomerated corks (granules glued together) with natural cork discs glued to the bottom. These offer consistent density and a reliable seal against high pressure.

Whether opting for the classic cork assembly or a modern alternative, selecting the right closure is vital. It isn't just about preventing leaks; it's about preserving carbonation and maintaining the unique character of the wine until that celebratory pop.

[fs-toc-h3]Wine closures, in summary

The choice of closure for a bottle of wine is just as important as the bottle shape. Both are essential in preserving the liquid inside, but they also play an important role in brand appeal and customer experience. According to the 2021 Closure Survey Report from Wine Business Monthly, natural corks remain the most popular closure option among wineries; however, it's clear that other options are gaining traction. Ultimately, winemakers must consider bottle shape and closure when crafting their products to create a memorable experience for their customers.

• Amorimcork: Portuguese company that is the world's largest producer of cork stoppers, with a focus on sustainability and innovation. They offer a variety of natural cork closures for wines, spirits, and other beverages.
• Cork Supply: US-based producer of premium wine corks and closures, specializing in high-quality natural cork products. They offer a wide range of closure options to meet the needs of winemakers around the world.
• Diam Closures: French manufacturer of synthetic wine closures made from polyethylene terephthalate (PET) material. Their products are designed to provide an oxygen barrier and preserve the quality of wines over time.
• Etched Images: US-based producer of sealing wax for wine closures. They also specialize in creating unique designs for wineries looking to add a personal touch to their bottles.
• G3 Enterprises: US-based manufacturer of wine capsules, foil capsules, and shrink sleeves for wineries around the world. They specialize in providing custom solutions for their clients’ packaging needs.
• Inspiral: UK-based manufacturer of natural cork stoppers for wines and spirits as well as other beverage applications such as beer and cider. Their products are designed to provide an airtight seal while preserving the taste and aroma of the beverage inside.
• Ramondin: Spanish company that produces natural cork stoppers for wines, spirits, liqueurs, olive oils, vinegars, and other beverages. They specialize in providing high-quality corks that are designed to preserve flavor and aroma over time.
• Vinolok: Czech Republic-based producer of glass closure systems for wines, spirits, liqueurs, olive oils, vinegars, beers, and other beverages. Their products are designed to provide an airtight seal while preserving flavor and aroma over time without affecting the taste or smell of the beverage inside.
• Vinvention: French manufacturer of synthetic wine closures made from polyethylene terephthalate (PET) material with patented oxygen scavenging technology that preserves flavor and aroma over time without affecting taste or smell inside the bottle.
  
• Verallia is a leading North American supplier of beer and liquor bottles as well as other beverage containers such as cans and jars. They are committed to providing innovative packaging solutions for their customers.