There is a lot of commentary out about “corked” wine.  Some of that commentary seems designed to create mystery or intimidation. This post is not that.  The goals are simple:  Explain what corked wine is, how to tell if wine is corked and what to do if you discover your bottle of wine is corked.

Let’s start with a couple facts:


  • Only about 5% of all wine that comes in a bottle with a cork is “corked.”
  • Being corked has nothing to do with finding pieces of cork in your wine.
  • If wine is not from a bottle with a cork, it may still have issues, but it is not corked.
  • You can’t tell if wine is corked by smelling the cork.
  • In the very unlikely event that a bottle of wine you get from Locals is, in your opinion, corked, then we replace it – no questions asked – ever.  

So with that out of the way, a little science.  Corked wine is something very specific.  It is wine that has been contaminated with cork taint.  Cork is a natural product and some little microorganisms like to eat it, either while it is still part of a tree or after it has been turned into a wine cork.  In some cases these organisms unite with others causing a chemical reaction that creates a compound called TCA.  If wine comes into contact with TCA, it’s corked.  Once let loose, TCA can contaminate a single cork or it can infect an entire cellar or winery.

Surprisingly, it was not until the 1990’s that a major culprit in the occurrence of corked wine was discovered – chlorine.   Scientists discovered that a significant amount of cork taint was being caused by the interaction of chlorine with the natural occurring fungi in the cork.  Since this discovery most wineries have totally eliminated the use of chlorine-based cleaning products, reducing the risk of cork taint.  Reducing, but not eliminating.  Interactions between cork fungi and other substances are inevitable and the possibility of the chemical reaction resulting in TCA cannot be eliminated.

Corked wine is not harmful to drink, just unpleasant.  The obviousness of the corked smell and taste depends on the extent of the taint and the wine drinker’s sensitivity.  Your sensitivity to taint has nothing to do with your level of “wine sophistication.”  

The smell of corked wine has been described as being like damp, smelly cardboard.  Put in slightly less graphic terms, cork taint dulls the fruit in a wine, renders it lackluster and cuts the finish.  Some people find the taste astringent.  

You should always be comfortable sending a wine back if you perceive it to be corked.  It is very unlikely that your conclusion will be challenged and it should not be.  Remember that not all flaws with a wine are a result of it being corked.  Perhaps describing the taste and smell of the wine is better than attaching a label to the cause.  But you purchase wine to enjoy it and to enhance an experience.  A dull, lackluster wine will not do that.  Trust your judgment and palate and return the bottle.

As an aside, do not equate the presence of “crystals” on a cork with taint.  These are formed by tartaric acid, a natural component found in grapes.  This substance binds with potassium under cold conditions to form crystals.  Because white wine is often chilled the crystals occur more often on whites than reds, but a red wine exposed to cold temperatures during shipping, for example, may also have crystals on the cork.  Wines makers can eliminate the possibility of crystals by chilling the wine to near freezing before bottling, a process called “cold stabilizing,” and allowing the crystals to form and “precipitate out” at that time.  Some wine drinkers welcome finding crystals on a cork as it is a sign that the winemaker has chosen not to “interfere” with the wine making process.

What if you can’t return a bottle?  You purchased a special bottle of wine while on vacation and open it on the first anniversary of your trip and find it to be corked.  Scientists at UC Davis have discovered a possible solution (which I have not tested).  The scientists placed a wad of plastic wrap in a container and poured in the wine.  After about 15 minutes they poured the wine into a new vessel leaving the plastic wrap behind.  Apparently, TCA bonds with plastic wrap and the wine is no longer corked.  Hard to say how this process will affect your wine drinking experience but it’s certainly an interesting experiment!