Monday, May 24, 2010

The cork, screwcap and diam debate

The passion and spirit of the late Dr John Middleton continues to walk the paths of the Yarra Valley. Mount Mary’s recent newsletter has some interesting things to say about screwcaps, against a background of a move from one-piece natural cork to Diam. I have no quarrel about the choice of Diam, although I question the belief of the Mount Mary team that the overriding problem of one-piece natural cork is or was TCA, when in fact the major problem is random oxidation due to the inherent variability of each and every cork’s oxygen barrier capacity.

What is intriguing is the assertion that one should ‘consider the copper that is added to wines under screwcap to keep the sulphides at bay’. No competent winemaker would add copper in such an amount and at such a point of time that any copper or copper sulphate would remain in the wine. We certainly don’t do that at Coldstream Hills, and I am pretty certain there are very few who do.

The carbon footprint issue also arises. Anyone who has been to Portugal to see the cork production process knows that considerable amounts of energy are used at various stages of the harvesting and treatment of cork, before it is then transported around the world. Diam involves an extra level. It may be light, but it has a considerable volume, and this is part of the shipping cost calculation. Screwcaps are made in Australia with minimal transport/carbon footprint consequences. This, I readily acknowledge, will have passionate advocates on either side of the debate. Also, I am unaware of aluminium toxicity causing proven health problems in Australia. It’s certainly not asbestos.


Belinda said...

Hi James, great post. So good for people to realise the random oxidisation is as much or more of a problem than TCA. Re cork - those pro want us to feel guilty about Portuguese people losing their jobs and the future of the cork forests but never (of course) acknowledge the carbon footprint! And as for Diam, yes, maybe no TCA but...? And they look so bad - like cheap aglomerates!

Leanne Hayward said...

Aah! Diam does not look THAT bad! Looks quite acceptable to me, and it IS cork albeit without TCA

Unknown said...

Diam continues to monitor and reduce its carbon footprint

Anonymous said...

Hi belinda,

Beautiful post.

I'm always astounded by the elegance of screwcaps every time I decant some tomato sauce onto my sausages.

Adios, big red

Madalena Santos said...

In fact... My memories are plenty of cheerfull moments, celebrated by the unique pop of a... screw cap?!
Oh, no! My memories go on making a joyfull cork pop! I whish the future goes on the same way!
Elegant as a natural product may be; soft as cork may be; natural as only cork stopper may be; cheering all our good moments as only its pop does!
Greetings from Portugal where thousands of people live on the love for cork: a great present, a great future!

pedro said...

This isn't about portuguese unemployment or "montado" conservation. It's about your social and ecological responsibility. Mr. Halliday are you aware about energy consuption and environment destruction regarding aluminun mining? Please take a look at this post
I'm sure you are concerned also about Australian future. In Portugal, fortunately, we were taught to be kind with nature. I'm sure this is the only path to take. I'll read your blog more often. ;)

Anonymous said...

The production of cork stoppers need energy of course but less than aluminium. The big difference is that the cork tree before obtain a bark of 9 or 10 years old to obtain the necessary thickness to make an stopper has been captivating big quantities of CO2. A cork tree harvested between 10 and 14 times during his live captivates 7 or 8 times more CO2 than a cork tree never harvested.

Manuel Ribas said...

Hi everybody,
A nice bottle of good wine will always be conected to a natural cork.
The reason why? Centuries of experience and tradition.
Screw caps have a pharmacy and chemical look.
The main issue here can be the cost but all good things in life are more expensive.
For those who disagree I would suggest to open a screw cap botlle of wine and than drink it in an aluminium or plastic "glass".
How does it feel?
At the end wine corks shall overcome.

Filipe said...

Hi! Interesting Post and Blog. I will follow it for sure! I don't doubt that the Ecological and future choice is natural one piece cork. And I don't doubt that in future everyone will preserve all the Forests in the World. Choose one piece cork!

Luís Roboredo said...

Portuguese wines generaly are classic wines, the "arte" of wine here in Portugal exists since the time of the romans...
Tchim tchim ...

Lillian said...

How can you suggest that screwcap production has minimal carbon footprint consequences? Have you considered the environmental impact associated with mining and smelting aluminium and the total amount of energy used in the process of manufacturing screwcaps? Transport is only one component when determining the environmental performance of a product over its life cycle.

David Middleton said...

You are quite correct James, to point out the existence of random oxidation. Indeed, this very problem, along with TCA, was the reason we switched closures. Neither of these problems are an issue for us now, thanks to DIAM.

I must take issue with many comments being made regarding carbon footprint and environmental acceptability. You contend that aluminium production is more environmentally acceptable than cork production particularly with regard to carbon. I disagree.

During your trip to Portugal you were interested and observant enough to make an assessment of the energetics of cork production and judged it to be highly energetic. Perhaps you should apply the same level of investigative enthusiasm to Victoria's aluminium smelters. I wonder if your independent assessment would agree with the figures provided by the government and the industry itself.

- To see my full response to James' comments please follow this link:

- The newsletter that James was referring to can be viewed in full here:

Mary said...

Good discussion here!
Anytime I have too chose I go on choosing natural. I pay the price, but I'm trying to be sure that Nature - our home - does not!
I 'm trying to leave a home for the generations that will overcome me.
No doubt that cork is the only sustainable choice for closure and, as I understand, also a reliable technical choice.
Plastics an aluminium may be fantastic - but do not try to make them more than they really are: a cheap solution for fast consuming wines.
Plastic comes from petroleum (all said about sustainability and world conflicts) and aluminium transformation keeps poisoning our planet (do you know that some countries have prohibited aluminium kitchenware for they impact in public health? that's tue!).

Plesa, keep yourselves informed.
Make the wright choice!


Anonymous said...

Wow, look at the voting. Seems they're in a twitter over at @winecompanion. Those pesky portuguese hijacking the poll. What did they expect? That the United Aluminium Workers Alliance would storm the poll and give a resounding victory to the cap? it's not too late, I'm sure they could be rallied.

Why would someone put a juvenile poll on their blog, and expect an informed and intelligent response. These polls are the way of tabloid journalism. Must be the level at which this blog is aimed.

Thurston Howell III

Anonymous said...

Do any of these corky people drive cars I wonder? those footprints!
It is as James says all about unnecessary variability in wines;something no winemaker wants to see.
Back to goats stomachs uses a lot of energy to produce and is also very heavy.

Mary said...

I really hope tat these two last Anonymous people have a life full of other good choices for our Planet.
If they have, well, I guess we may go on living quite as good as we do today.
But, I must confess, I'm affraid they aren't...
(as we say: Sensible people do not kill animals, sensible people eat animals!)
As someone already state: we are talking about closures with high technical performance - why do not choose the best one for Nature?

Anonymous said...

I'd like to share an observation... Last November I visited the Hong Kong International Wine and Spirits Fair. Just about every wine producing nation on earth was represented: old world, new world, EVERY wine producing country had a presence. Some of those presences were huge encompassing 3 aisles (Spain / France), some small (Thailand/India with small booths).
My observation is this. With the exception of one or two specific wineries in the USA and South Africa the ONLY nations with their wines under screwcap (90% plus) were from Australia and New Zealand. Now. Imagine you are a Chinese national buying a bottle of wine as a gift or to take to a dinner party or even to dine with that night. Which wine are you NOT going to buy, when faced with wines from every wine producing nation on Earth. Is it the Burgundy...Rioja...Napa Valley...Bordeaux...Argentinean...Chilean...under cork? Or will it be and Australian wine under a screwcap? To be honest my feeling is the swing to screwcap has been too much..too soon without really evaluating the consequences. In my heart I feel that screwcaps have done nothing except reinforce the view in some worldwide markets that Australian wines are cheaply made and insubstantial. I understand the technical reasons for screwcap: I really do...but ALL factors need to be considered before laying the entire Australian winemaking image at the foot of an aluminium idol.

Anonymous said...


The hijacking of this thread has almost rendered it useless; but alas, I shall put in my two bobs worth.

I have a green slant, and vote green, as I believe that is the best way that I can help the world I am concerned with. But a good life, very much like a good wine, is all about balance. There will always be cork and there will always be aluminium. They both have a large “carbon footprint”, and they both have great uses.

But when I open my 10 or 20 year old Rieslings (and Cabernet, Shiraz, Pinot and ...) in the future, I will be thanking those Clare Valley producers for their stance; for it is I who will be enjoying some spectacular – and consistent – wines. I’ll take screwcaps any day.

And for those who are debating this topic with their mouths before engaging their brains – you can all get screwcapped.



John said...

Hi James,

I too was shocked at Middleton's comment regarding the use of copper in wines. It was an inflammatory statement that showed no knowledge of the workings of other winemakers and I suspect it was made in part to justify his Diam choice. I wonder what he would think of the old world winemakers using copper fittings...

One aspect of the debate that hasn't been mentioned here is the lower levels of sulphur dioxide that are generally used in screw cap wines. The very nature of cork closures means that pre bottling free sulphur dioxide levels can be very high. These high levels are not necessary in screw cap wines. That has to be a good thing for the consumer.

Brian said...

All I can say is that when we bottled our first Merlot in 2001 we said we would use the best cork we could find. As most of our sales are via mail order in case lots we have developed a reasonable data base.
Within three years we had people getting back to us complaining about the variability within a case. TCA was the least of the problems, it was the variations in oxidation. They are ordinary wine lovers who liked to share a bottle with friends, tell the story of where it came from and how they found it, and enjoy. The problem was that one bottle was brilliant and the next ordinary, or worse.
By 2006 we had had enough and switched to screw caps. Now people drink the wine we produced, not the random result of a cork lottery.

Andrew Smith said...

Got to say I love the Diams. The twin issues of random oxidation and TCA have largely been solved by Diam. The seal is excellent, and we have had no QC problems in the 5 years we've been using them.
Random Ox was a bigger problem than TCA and its so gratifying to see the Champagne equivalent "Spark" being so widely used by true Champagne. Sparkling wines show TCA very badly, so if these people like it..we're onto a good thing.
No real issues with screwcap for some styles, the trials I di with big red suggest that the bigger the red , the worse it ages under screwcap.
Between Diam and a capsule.we're paying roughly 3 times as much as for a I guess we are putting our money where our mouth is.
Having said that...I do bottle our Riesling under screwcap.
Its the best closure for that style.
So, maybe there isn't just one size fits all closure.

Peter said...

The issue with corks including diam is that they are inserted into the neck of the bottle and rely on the pressure of the cork on the sides of the bottle. This leaves the cork prone to moving in and out of the bottle as the volume of liquid changes dues to temperature fluctuations. As a screw cap is applied by torque onto the lip, it can withstand higher pressures from within the bottle and therefore protects the wine from the ingress of oxygen caused by movements of the cork. The French learnt this years ago when by applying a crown seal to champagne fermented in the bottle. To some a cork may look nicer and have a pop when its removed from the bottle, but you cant have consistent quality if the closure is prone to variations that are outside the winemakers control.

Anonymous said...

People, people, people! Wine is supposed to be bringing pleasure to us all, not tear us apart. Seems you all haven't had a good shag in a while. I could recommend a few good prostitues for you, but by the look of things even a bad one would do.
If you just can't stomach sex then maybe drugs are the only remaining option for a prescription. I've never thought of wine as a gateway drug to harder things but in this case I believe it may be necessary. Start with weed and move your way quickly up from there.
Hell, one poster even found some comments 'shocking'. An earthquake that kills thousands is shocking. There is someone with a dire need for a good root, or at least a dose of some perspective.

Yours in epicurious delight,

Wine Righters Of the New Generation (WRONG)
Our motto: (high) society ceases to function without us

Paul C said...

As both a consumer & collector, I would encourage anyone who enjoys Premium Australian reds to read the book "To Cork or not to Cork" by George M Taber and hopefully be inspired to look further into the subject. I am concerned that the trend in Australia to use screwcap closures on premium red wines not only lessens the experience & event that sharing a special bottle of wine can be, but more worryingly, introduces faults of its own & reduces its capacity to evolve with time.

Anonymous said...

It's interesting how willing the screwcap army are to completely ignore key pieces of factual information regarding the negative aspects of the closure. John, I suspect you won't bother but you should take a look at this link: Since the increased use of the screwcap the AWRI have noticed a trend towards winemakers opting for a pre bottling addition of copper to their wines.

Bottling under screwcap may allow for less SO2 addition, however no mention has been made of the increased persistence of free SO2 in wines under screwcap as opposed to cork or diam (dependent on the permeability level of the diam chosen). Regardless of the amount of SO2 added pre bottling the level of free SO2 in aged wines is likely to be greater under screwcap than cork or diam.

This debate has nothing to do with copper fittings or trading the car in for the horse and cart. It's about choosing the best reasonable option, all things considered!

The screwcap closure (although unnecessary) may adequately do the job for white wines made for early consumption. If you are one inclined to enjoy a well aged wine follow the lead of the top Domaines of France. Avoid the cap.


Belinda said...

Cripes - came back here to look up something and couldn't help but read through all these posts - I was the first one - maybe I'll be the last...We have forgotten that the cork vs screwcap debate is about preserving a wine's quality so that the consumer can enjoy it as it was designed. What could be worse than nurturing vineyards for years, producing wonderful wines and having them ruined by the thing we use to stopper the bottle! Nuts! And as one very preeminent lady in wine said 'I can't see mass-market consumers returning to corkscrews for the sake of the Alentejo ecosystem.'

Winefly said...

Belinda well said.
After trialling hand selected corks (@$1:80 each) vs screw caps since 2002 on $20-$100 reds as well as whites the good cork shows very little difference to the screw caps in maturation but there was still the woody character in 2 of the cork stoppered wines.

Chris said...

You producers or those associated with production have posted many of the above comments. As such, you are emotionally tied to a particular closure in many cases.

Understand my view as a purchaser and consumer of your wine - what I want is to be able to open a bottle and taste it as the producer meant it to taste. Screwcap or Diam seem to give me the best chance of that. I know the jury is out on both until more long-term research is avaialable, but from what is around so far I go screwcap as my preferred choice. I haven't had any issues with wines under that seal to date, and around 10% of my wines under cork are TCA affected to some degree or prematurely oxidised - for me, that is throwing hundreds of dollars down the drain every year. I have ceased buying White Burgundy and Chablis because of the randox issue - as soon as the premier and grand crus move to screwcap I will start again.

Chris H
Melbourne, Australia

Anonymous said...

so having spent years telling all and sundry that TCA was the problem, the australian wine dogma types would now tell the world they are still wrong, but for different reasons i.e. now its random oxidation.

Like all embedded dogma it lacks reason and balanced debate.

Anonymous said...

I live Australia for 2 years now, and the universal use of screwcaps in this country was a disappointment. Feels like all wines are cheap wines, and opening a bottle of wine feels like opening a bottle of sprite.

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