Screwcap, DIAM, and Nomacorc (pictured here) are the three most popular alternative closures in Washington

Below is a tabulation of closure choice and cork taint data from my tastings for Wine Enthusiast in 2018. I have also included data from 2017 and 2016, previously published. Here are eight takeaways.

1. Natural cork continues to be the most frequently used wine closure

Natural cork closures continue to make up about three quarters of the market in Washington (74.15%). While this number was down slightly from previous years, additional data would be needed to say whether this represents a trend or is just normal variance. Note that in the natural cork category, I include all 1+1 corks and related variants, as well as any agglomerative corks that are not guaranteed to be free of potential taint.

2. Cork taint remains a significant problem with natural cork closures

5.18% of the wines I sampled in 2018 appeared to be affected by trichloroanisole (TCA) contamination. This is within the range that I have seen in previous years (3.59% to 6.21%).

Note that I say ‘appeared to be affected’ because these numbers are based on sensory examination, not laboratory testing. However, I only included wines in my tally that both myself and one other person (in all cases my wife, who is more sensitive to cork taint than I am and who has worked as a wine professional) agreed showed signs of TCA contamination.

The relative stability of this number seems somewhat surprising given the introduction of natural corks individually tested for TCA contamination. However, I have been told throughput remains an issue to accessing these corks, and their higher price point also discourages some from using them.

Moreover, one-by-one testing remains very new technology. For example, Amorim announced its NDTech corks in May of 2016. So presumably many of the wines using these closures haven’t seen the light of day yet. Finally, I should note that it is impossible for me to say how many producers for the wines I taste are actually using these individually tested corks at present.

3. Cork taint is not just an issue for inexpensive wines

One fallacy about cork taint is that it is mainly an issue for inexpensive wines. I have noted in the past that this is not the case in my experience. My tastings in 2018 again confirmed this.

The average price of a cork tainted wine that I sampled in 2018 was just under $43, with a maximum price of $120 and a minimum price of $18. Those are not inexpensive wines. In fact, it could be said that none of the cork tainted wines I sampled in 2018 were inexpensive wines based on these data.

4. Cork taint presents more commonly in red wines

Of the cork tainted wines I detected in 2018, 95% were red wines. This is up from 84% in 2017.

There are several possible explanations for this. First, alternative closures, such as screwcaps, are much more frequently used in Washington for white wines (I hope to roll data for this up formally in the future).

Secondly, the red wines I am tasting have frequently spent longer in bottle than their white wine counterparts. This might provide greater opportunity for the cork taint to present itself in the wine. This is among the reasons I am a proponent of smelling corks when opening a bottle of wine. It’s possible that cork taint will be detectable on the cork itself but not yet necessarily detectable on the wine.

5. Screwcaps continue to be the most frequently used alternative closure to natural cork

Of alternative closures, screwcaps remain in the lead, used on 12.3% of the wines I opened for Wine Enthusiast in 2018. This is consistent with what I saw in 2017.

6. DIAM closures appear to be closing ground on screwcaps

The second most frequently used alternative closure was DIAM microagglomerative corks (9.3%). These closures (see an image of one on a Mark Ryan Winery cork above) are guaranteed to be free of TCA and other contaminants. Use of these closures has been on the rise in Washington in the last three years in the wines I’ve tasted for review (5.69% in 2016 and 8.56% in 2017).

7. Use of other alternative closures remains limited

The percentage of bottles using Nomacorc – a cork-like closure made from sugarcane – more than doubled from the previous year, and this is Washington’s third most popular alternative closure. However, the actual percentage of wines sealed under Nomacorc still remains very low (2.7%). This is surprising to me, as it seems like an excellent alternative that is cost competitive and keeps the natural cork-like experience (and is also carbon neutral).

Of note, L’Ecole No. 41 recently switched all of its Columbia Valley appellated wines to Nomacorc. The winery had previously been using them on its white wines and Frenchtown Red. Kiona Vineyards, meanwhile, uses Nomacorcs on approximately 80% of their total production (the winery makes roughly 25,000 cases of wine annually).

Use of other alternative closures/packaging, such as crown cap, glass stopper, cans, and VINC DS100 remain very low and were included in the ‘Other’ category (1.4%).

8. Washington continues to be a red wine dominated state

Finally, moving away from discussions of closures and cork taint, Washington continues to be dominated by red wines. A shade over three-quarters of the wines I sampled in 2018 were red wines. Whites made up 20% of wines sampled with rosés the remaining percentage (Note: I grouped sparkling wines and dessert wines into one of those three categories; in future years, I might break them out). These percentages are consistent with what I saw in 2017.

The numbers for all of these data are presented below.



# Natural cork

# Corked

Avg $ Corked

# Screw



# Noma


# Other closure


(75.28% red; 
20.04% white; 4.68% rosé)




(95.3% red; 4.7% white)


Max: $120









(75.25% red;

21.54% white;

3.21% rosé)



(84.09%   red;

11.36% white; 4.55% rosé)


Max: $95

Min: $10







Numbers not available)




Max: $80

Min: $10







Note: Table also includes a small amount of data from Idaho.