Well, I think I just found “the horse’s mouth.”

You may know that I’ve been trying to get to the bottom of the “cork vs screw cap” issue, and I just spoke with  a true authority on the subject — someone who’s run some very rigorous trials on the viability and age-ability of natural cork, synthetic corks and screw caps.

And the verdict is in! Well, there’s not just one verdict: it turns out that (as usual) the truth is not black and white. Here’s the whole scoop and nothing but the scoop…

This winemaker and his associates at an award-winning Washington State winery compared the performance of natural cork, synthetic cork and screw caps on both red and white wines (Merlot and Chardonnay) and for periods ranging from 3 – 12 months, 12 – 24, 24 – 36, and long-term. They found that:

A – Synthetic cork is too permeable: it allows too much oxygen to enter the bottle, which speeds up the wine’s aging process. For white wines, this means that they lose their fresh flavors too quickly and have a very short shelf life. For reds, the effects of aging are usually desirable, but only in a controlled, predictable, timely way. Winemaker and company decided synthetic was not useful for any of their wines.

B – Natural cork was running at an average 15% failure rate, which meant that 15 out of every 100 bottles (or about two bottles in every single case of wine) were contaminated by TCA cork taint (if you want to know more about TCA, watch my YouTube video, Cork vs Screw Caps). On top of that, they found that corks are like snowflakes: each one is unique and just a little different from every other cork. That meant that test results were not totally consistent for any time period. But for permeability, natural cork generally allowed less oxygen into the wine than synthetic, but more than screw cap.  They concluded that for reds that are meant to be drunk within three years, natural cork’s permeability is like Baby Bears’ bed: not too long, not too short, but just right.

C – Screw caps were the least permeable, allowing less oxygen into the wine than both other closures. The wine people decided they really liked what that did for their whites, because it kept the flavors fresher and brighter for longer. That performance was NOT ideal for the short-term reds, because the tannins weren’t able to soften quickly enough to make the wine taste its best in the near term. However, for reds that were meant for long-term aging (anything over three years) they loved what screw caps did for the wine.

So it’s simple, right? Natural cork for reds that will be drunk anytime between tomorrow and three years hence, and screw  caps for all whites and age-worthy reds.

Oh, there’s just one more wrinkle: screw caps can be made with a range of different membranes inside, which can significantly impact the permeability issue. So research continues, to determine whether screw caps with a variety of membranes can be made to work for every type of wine. I told you the truth wasn’t black and white…

Thanks to David Forsyth and the great folks at Mercer Estates for this really useful information. I’ll be reviewing some of their wines soon, and I can’t wait to tell you how much I enjoyed them, cork, screw cap and all. Cheers!

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