What is a Cork?

What is a Cork?
Corks are not all the same, says Peter F May, and they give clues to the quality of wine in the bottle.

I am frequently asked why sommeliers present diners the cork after opening a wine bottle and what the bemused diner should do with the thing. The answer is nothing, put it down on the table because you cannot tell if a wine is faulty from the cork, only smelling and tasting will show flaws.

But when the waiter has left and you have a spare moment you might like to take a look at the cork because it will you something about the wine.
We generally refer to corks as if they are all the same but there are differences between the various cork closures and since they determine the cost of the cork to the winery we can consider that the better a wine is, the better cork it has.

Corks cost wineries anything from ten to 50 cents each, so if you are producing 100,000 wines annually you could save $40,000 a year by using the cheapest cork.

Corks are made from the bark of Quercus suber which is a type of oak native to countries around the Mediterranean. The tree has the unusual property of surviving after its bark is removed and growing new bark, so trees are harvested around every ten years. A tube of bark is cut out and that is the closure you see in your wine bottle.

But trees are organic and bark varies in quality depending on individual tree, how old the tree is and whereabouts on the tree the bark comes from. Bark free of holes, cracks and other imperfections is used for premium corks.
So take a look at the cork. The longer the cork the more expensive. Top wines meant for aging can have two-inch long corks, cheap wines for immediate consumption half that. Now look at the surface; better corks will be pale and without flaws, holes and cracks.

An even cheaper ‘cork’ is made by grinding up the leftovers and moulding them with glue to make artificial corks, known as agglomerates. You’ll see a crumb-like texture. There’s a version, known as a twin-top which has a slice of pure cork stuck at each end.

I am no fan of corks but if you have to have one then I respect the DIAM, which is known in the trade as a ‘technical’ cork. This looks like an agglomerate. It is made from ground cork and synthetics and treated to guarantee against cork taint. The brand name DIAM is stamped on the closure. These are expensive and are a sign the winery is serious about getting the wine to you in the best condition.

So no matter what the restaurant prices the wine at, you can have a good guess at how the winery priced it from the clues in the cork.

Peter F May is the author of Marilyn Merlot and the Naked Grape: Odd Wines from Around the World which features more than 100 wine labels and the stories behind them, and PINOTAGE: Behind the Legends of South Africa’s Own Wine which tells the story behind the Pinotage wine and grape.

The Pulltap
The Pulltap corkscrew is the type I use. It is easy to use, easy to carry in a pocket and almost indistructible. And inexpensive! Highly recommended.

The Screwpull
This was revolutionary. No pulling or levering, just keep turning the handle and the cork rises out of the bottle with no effort. This was the first to use Teflon coating. I have bought several of these in the past but in time, with the heavy use I give my openers, the plastic prong has broken. But I note that now they come with a five year guarantee. This opener is so easy to use. Highly recommended

You Should Also Read:
Cork or Screwcap?
Choosing a Corkscrew
What is the Dimple in Wine Bottles for?

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This content was written by Peter F May. If you wish to use this content in any manner, you need written permission. Contact Peter F May for details.