Most mid-high range sparkling wines are closed using a stopper with two natural cork discs. These types of stoppers belong to the technical stopper family, and they are composed of an agglomerate body and two discs of natural cork on the end that comes into contact with the wine to ensure absolute safety.
This closure system is considered the best choice for sparkling wine thanks to its numerous properties, which provide optimal characteristics and aromatic notes in the aging of the wine, and ensure pressure is maintained from the time the wine is bottled until it is consumed. As a result, its quality, state of preservation and, of course, its magnificent flavor are guaranteed.
What is the double-disc system in cork stoppers?
The simple design of double-disc stoppers is the result of years of perfecting a long tradition that has always sought to offer the best possible conditions for wine to age and develop its best characteristics.
For this reason, this design combines 100% natural cork of the highest quality with an agglomerate body that guarantees an airtight seal.
How it functions is simple: the agglomerate body acts as the main occlusive element, adapting to the walls of the bottle neck with the exact pressure needed to withstand the 6 bars of pressure exerted by the carbon dioxide gas of sparkling wines. At the same time, it ensures users enjoy a smooth uncorking, a ritual so synonymous with celebrations and also with a product increasingly highly regarded for its quality.
The two cork discs are the heart and soul of this stopper, keeping the wine protected in an atmosphere of natural elements, providing aromatic notes and a smooth and regular oxygenation, while protecting it from coming into contact with the glue of the agglomerate body.
The agglomerate body is usually around 36 mm, and each of the two natural cork discs are around 5 to 6 mm thick, i.e., around 10 to 12 mm in total, although sizes can differ. They also have a chamfer of around 4 mm to help orient the stopper correctly on the bottling line.
There are different reasons why the double-disc system is used for cork stoppers for sparkling wines:
Protecting the taste
The 100% natural cork discs are the only element in contact with the wine, performing two main functions: preventing the wine from coming into contact with the agglomerate body; and adding natural aromatic notes to the final taste.
Leakage prevention
The discs used in this type of stopper are very resistant, so they can perfectly withstand the pressure exerted by sparkling wines, providing a very stable physical seal.
Maintaining quality in sparkling wine aging
These types of stoppers are excellent at insulating the wine from the outside, maintaining the necessary concentration of CO2 inside the bottle, but regulating a gentle inflow of air from the natural cork cells, which prevent both the oxidation and asphyxiation of the sparkling wine.
Agglomerate body
The agglomerate body is made up of cork granules. Each manufacturer selects their own cork granule size, the best being medium granules because they reduce the amount of glue used in each stopper and contain higher quantities of natural cork.
The agglomerate body is the largest piece of the stopper, so the way it is manufactured and its composition greatly affect the environmental impact.
Certified food-safe glues are used for its production, which bind the cork granules to form a homogeneous body.
The uniformity of this part ensures a perfect seal and adaptability.
Granule size
Cork granules are obtained from the crushing of natural cork, through a mechanical grinding process, followed by granulometric classification, washing off the dust and soil, and equalizing moisture.
Granulated cork can be found in a variety of sizes and densities: from lower density cork dust (0.5–2 mm) to medium sized granules (3–7 mm), which provide higher quality for the sparkling wine. In general, the more balanced the density, the better the seal, and logically, the higher quality stoppers will be those using medium grain sizes.
100% natural cork discs
The second element of this type of stopper is the discs made with 100% natural cork, following the same production process as natural cork stoppers. Each disc has a diameter of 34 mm and a thickness of 6 mm.
They are glued to the agglomerate body on one of the ends using food-safe glue. By binding the disc to the body, it is possible to produce various types of stoppers. Mainly:
- Agglomerate cork stoppers to which two natural cork discs are glued to the same end, placing the higher quality disc at the bottom where it will be in contact with the wine.
- Agglomerate cork stoppers to which a single natural cork disc is glued on the lower end in contact with the wine, known as 0+1 stoppers.
Glues used to manufacture the bonding and gluing of the discs
The glues used in the production process in the sparkling wine stopper industry are mainly polyurethane based.
A prepolymer is used to manufacture the agglomerate body, which, thanks to a catalyst, is converted into a rubbery plastic suitable for contact with food.
Casein glue can also be used for gluing natural cork discs, although it is no longer in use because it has allergenic components, and water-based polyurethane emulsion is the most widely used today. In addition to being suitable for food contact, it does not present the same problems as casein.
Benefits of this stopper
Of all the corking systems, designs and materials, the cork stopper with two natural cork discs is the one chosen by the best brands for the best qualities, and not for nothing: numerous studies endorse this type of stopper as the one that provides the most benefits to the wine.
Safety
The two natural cork discs safely protect the wine from coming into contact with the binding glues, prevent leaks, prevent the entry of foreign elements, and regulate the entry of air to provide proper oxygenation.
Quality aging
All the parts of this stopper offer what to date have been proven to be the best conditions for the aging of wine. Since this material offers the ideal characteristics of flexibility, lightness, airtightness, and impermeability, the wine held by this stopper can age in the best possible way while staying protected. It should be noted that this cork stopper, which contains no expanding agents, naturally recovers its original shape purely due to the intrinsic properties of the cork.
Oxygenation
Cork is being studied for its ability to gently and stably filter oxygen into the wine. Cork has proven many times to be capable of maintaining optimum conditions in aged bottles, even up to a hundred years.
Aromatic notes
The experts agree: natural cork adds very valuable aromatic notes to wine.
After numerous studies and research, experts have agreed that wines corked with good quality natural corks had more complex and interesting aromatic essences and traits, giving them extra value.
Sustainability and eco-friendliness
The cork stopper is an eco-friendly and sustainable material. Its production is responsible for capturing up to 14 million tons of CO2 each year. In contrast, other industries like plastic and metal production—the main alternative materials to cork—pollute up to 10 times more.
Consumers’ perception of quality
Many market surveys and studies conclude that the vast majority of wine consumers all over the world perceive cork stoppers as a symbol of higher quality and elegance, and are willing to pay more for a bottle sealed with a cork.
Key points to remember
Stoppers with two natural cork discs are the best choice for sparkling wines. This is because they are able to withstand all the pressure inside the bottle, provide optimum oxygenation for years, and contribute valuable aromatic notes, increasing the final value of the sparkling wine.
What’s more, this type of technical stopper, such as the ones we provide at TESA, undergo strict and meticulous manufacturing and quality control, and they are the best guarantee of quality for your sparkling wine.
If you would like more information, please get in touch with us. We would be delighted to help you.