If, while surfing the Web, you have chosen to read our article, it means that you want to know why sparkling wines have a mushroom-shaped cork and what are the reasons that explain the choice to use this particular type of cork for this type of wine.

Below, we will explain everything. Just give us a few minutes of your time.

Why does the sparkling wine cork have a mushroom shape?

Photo: congerdesign from Pixabay

There must be a reason to explain the mushroom shape of the cork for sparkling wines. Otherwise, these corks would not be produced. So let's try to understand why bottles of sparkling wine have a mushroom-shaped cork.

Just like the organism commonly called mushroom, the cork of sparkling wines has two main parts: a cylindrical body, which constitutes the base of the cork, and the cap, the upper part, the widest one, enclosed by the metal cage and which emerges from the neck of the bottle. In other words, the cap of the cork is the part that is found on the outside of the bottle, while the body is the narrowest part that we find inside the bottle.

You should know that the mushroom cork takes on this typical shape only during and after its insertion process into the neck of the bottle. Let us explain better.

Initially, the sparkling wine cork has the classic cylindrical shape, typical of every cork of every other type of wine. In sparkling wines, about half of the cork is compressed and inserted into the neck of the bottle, while the other half remains outside. The compression made on the lower part of the cork and the elasticity of the cork narrow the body, which adapts to the shape of the neck of the bottle. The upper part, which remains outside the bottle, exposed to the air, expands, balancing the narrowing of the lower part and creating the typical mushroom cap. The internal pressure of the bubbles also contributes to causing this phenomenon, pushing upwards and facilitating the expansion of the cap.

Photo: Stockholm Paris Studio from Unsplash

This is important to understand the two reasons why sparkling wine corks are mushroom-shaped.

1️⃣ SPARKLING WINES HAVE A MUSHROOM-SHAPED CORK TO PRESERVE THE EFFERVESCENCE AND TO RESIST THE INTERNAL PRESSURE OF THE BUBBLES

What is the main characteristic of sparkling wines? Clearly the bubbles, the marked effervescence and, consequently, the high internal pressure. What tricks can be used to preserve these properties? There are many solutions, from the shape of the bottle to the use of a mushroom-shaped cork.

The key aspects to understanding the usefulness of the mushroom cork for preserving the effervescence of bubbles are to be found in the properties of the cork, in particular in its elasticity. Specifically, the cork is able to adapt perfectly to the neck of the bottle, to its internal walls, increasing the hermetic seal of the cork. The lower part of the cork, after being inserted into the neck of the bottle, tends to expand, trying to recompose the initial cylindrical shape, until it meets the walls of the neck of the bottle, to which it adheres firmly.

The upper part of the cork, which has widened, is essential to resist internal pressure. The effervescence of the bubbles causes pressure that pushes upwards and outwards. The cap has a larger surface area than the body of the cork. The fact that the pressure is distributed over a larger surface area prevents the cork from coming out. The metal cage, that keeps the cork firm, anchoring it to the neck of the bottle, contributes to this function.

2️⃣ SPARKLING WINES HAVE A MUSHROOM CAP TO MAKE OPENING THE BOTTLE EASIER

The mushroom-shaped cork makes opening the bottle easier.

The cap, emerging from the neck of the bottle, allows you to uncork the bottle without a corkscrew. Grab the mushroom-shaped cap, rotate it and the cork can be extracted safely.

This would be more difficult and less safe if you use a corkscrew.

That's it. Now you know why the mushroom cork is used to close bottles of sparkling wine.