What are synthetic wine corks made of?

Ask Dr Vinny

Hello there! I'm Dr. Vinifera, but you can call me Vinny. Ask me your toughest wine questions, from the fine points of etiquette to the science of winemaking. And don't worry, I'm no wine snob—you can also ask me those "dumb questions" you're too embarrased to ask your wine geek friends! I hope you find my answers educational, empowering and even amusing. And don't forget to check out my most asked questions and my full archives for all my Q&A classics.

Dear Dr. Vinny,

What are synthetic wine corks made of?

—Adrian, United Kingdom

Dear Adrian,

The two main types of synthetic corks are made from either petrochemical-based plastics or plant-based plastics.

The petrochemical-based plastics are made from low-density polyethylene, a pliable type of plastic. Plastic pellets are melted down, and then turned into a foam consistency so they’ll mimic natural cork’s spongy texture, typically then covered with a smooth outer skin.

The plant-based plastic corks are similar in production, except that they are made from biopolyethylene, a type of renewable polyethylene that’s made from ethanol derived from the dehydration process of raw materials like sugarcane and sugar beets.

The plant-based synthetics are increasing in popularity, since they have a low carbon footprint and are renewable. Bioplastics like these are also commonly used to make water and soda bottles.

Why do some wineries choose synthetics over traditional natural corks, screwcaps or composites? Synthetic corks are cheap: They cost about a dime to 15 cents each, about the same as a composite cork; screwcaps can cost up to 25 cents, and good-quality natural corks can cost anywhere from 75 cents to $2. Some folks opt for synthetic corks to eliminate the risk of "cork taint," or the potential for irregularities that arises from using a natural product like cork.

I don’t mind synthetic corks, but they can be really hard to get out of the bottle—they can be so stiff sometimes that I’ve actually broken a corkscrew on a couple of them. I’ve also heard anecdotal reports that wine aged for a long time (years) under synthetic cork can take on some off odors or flavors that may be linked to the plastic.

—Dr. Vinny

Closures Ask Dr. Vinny

More In Dr. Vinny

In Italian wine, what’s the difference between DOC and DOCG?

Wine Spectator's expert Dr. Vinny explains the geographical wine classification system in …

Oct 4, 2022

Is it OK to brush my teeth before tasting wine? Does toothpaste change the way wine tastes?

Wine Spectator's resident wine expert Dr. Vinny explains why brushing your teeth and wine …

Sep 26, 2022

What’s the difference between Hermitage and Ermitage? Are they the same wine?

Wine Spectator's expert Dr. Vinny explains what the H is going on with Hermitage vs. …

Sep 19, 2022

When traveling, are any wines more or less susceptible to bottle shock than others?

Wine Spectator's expert Dr. Vinny explains the phenomenon of "bottle shock" and how to …

Sep 12, 2022

What’s the best way to remove a crumbly wine cork? I’ve tried everything!

Wine Spectator's expert Dr. Vinny offers tips for extracting crumbly corks, and how to …

Sep 7, 2022

What’s the difference between Petite Sirah and Syrah?

Wine Spectator's expert Dr. Vinny explains that Syrah and Petite Sirah have quite a bit in …

Aug 29, 2022