DIAM and the eventual triumph of empiricism…

Update 4.6.2020(1.3.2018)billn

A discussion of why I believe DIAM to be my closure of choice for white burgundy.

For a number of years I’ve recommended here in Burgundy Report that you either drink your white burgundy young – let’s say within 3-5 years of release – or that you buy wine sealed with an alternative closure to cork. I have been clear that, should you choose to keep your cork-sealed wines for the longer term, you risk losing a significant proportion of those bottles to oxidation.

Over the last half-dozen years, the market-share of DIAM has gone through the roof, but at the same time there have been dissenting voices; for instance over ‘the bitter taste of DIAM’ or that DIAM is an industrial product putting the livelihoods of artisanal cork producers at risk, or the habitats of lynx, or, or, or…

Despite such background noise the popularity of DIAM has continued to increase, with ever-more ‘important’ producers making the switch to this closure. More importantly to me, I simply never had a bad bottle that was sealed with DIAM, so this empirical view has always been a strong driver of both my purchasing and my recommendations.

Of-course, I don’t just want my wine to utilise a hermetic seal – what would be the fun, or intellectual interest in that? Wine has to develop, to change as it ages – in a positive fashion – otherwise a simple crown-cap, like a beer-bottle, would be enough.

So I chose to delve deeper into the world of DIAM, and also to look at whether wines sealed with DIAM actually develop in a way that somebody who loves more mature chardonnay – burgundy! – would recognise. For a long time this simply wasn’t possible – because we have had to wait for the DIAM-sealed bottles to age – waiting for what Penfolds would describe as the Rewards of Patience. That time has arrived. In this respect, possibly my most important tasting in years follows this article (see below.)

Some DIAM specifics

A DIAM, at first glance, looks just like a cork, and is removed from the bottle exactly like a cork – but on closer inspection, the appearance of its surface is more granular. A DIAM is still 95% cork, but cork that has been finely chopped before being ‘processed’ and then glued back together.

Although not officially commercialized before September 2004, the first ‘samples’ of what would become known as DIAM were shared with major producers in 2003 – in fact Bouchard Père et Fils* were the first to test this closure on their villages Meursault cuvée – at that time they used the equivalent of a DIAM5 though it didn’t yet have this marketing name.
*I well remember Bouchard’s winemaker at the time, Philippe Prost, telling me that after they had finally made the change to DIAM, he began to sleep more soundly – “Bottles simply stopped being returned to the domaine!”

Today there are DIAM 5s, 10s, and even 30s, plus new to the market a DIAM3 – ‘for the quick drinkers.’ Rightly or wrongly, the number is seen by the market as a shorthand for the number of years that the wine is assumed to be good. As the number increases, so does the density of the ‘seal’ and at the same time the relative oxygen transport through the ‘seal’ reduces. You may also come across DIAMGC – assumed to be shorthand for ‘grand cru’ – but this is actually a renamed DIAM10 – renamed because some consumers assume that the ’10’ is actually a sell-by date!

DIAM was developed at a time before early onset oxidation (premox or p.ox) was recognised as a significant problem, though today it is cited by the producer as the main reason for purchase. The actual target of the research was to produce a standard cork replacement – let’s call it a technical seal – that could be guaranteed as TCA free – i.e. no more corked wines. Their success came through processing the finely chopped cork with a supercritical fluid:

Supercritical Fluid (SCF):
Is any substance at a temperature and pressure above its critical point, where distinct liquid and gas phases do not exist. It can effuse through solids like a gas, and dissolve materials like a liquid.

In this case the supercritical fluid was CO2 mixed with a small quantity of water. The process is much harder to achieve than it first sounds, because carbon dioxide is a gas that only becomes supercritical at a very specific combination high pressure and particular temperature, but when achieved, the CO2 has the properties of both a gas and a liquid, becoming a formidable solvent with which to remove TCA – indeed any other impurity or volatile that might by dissolved by this ‘fluid’ – TCA is not the only impurity that comes from a cork.

This type of process is so effective that (amongst other uses) it is now used by Lavazza to remove caffeine from coffee – the American company Maxwell having first patented this process in the 1950s.

The formulation used by DIAM for putting their seal back together includes 95% of the processed cork, polyurethane (isocyanate) adhesive and some (plastic) microspheres to aid durability. In particular, the adhesive has been the lightning-rod for detractors; they say either that they can taste bitterness from the adhesive (I cannot) and/or that they are concerned by the (potentially) cancer-forming additives in isocyanate adhesives such as phthalates or Bisphenol A. Of-course I should point out that all the constituent parts of DIAM’s formulation are classed as acceptable by the relevant authorities for contact with different types of foodstuffs, including wine. More pertinently, that this is exactly the same adhesive that has been used to bond Champagne corks for the last 50 years (or-so) – very few Champagne corks are made from a single piece of cork. But on the other hand we should be clear that more of the same/old is not necessarily a good thing, so an isocyanate-free version would remove certain concerns – see later! Anyway, perspective is important, and a bottle of Champagne has little difference to a bottle of Bâtard-Montrachet which has been sealed with DIAM.

‘Protection’ for the investment put in by inventors are patents. There are two main types of patents, both of which are granted for about 20 years to protect inventors and allow them the opportunity to make a return on their investment:

  1. Patents by process – i.e. the particular steps you use to achieve something novel – and…
  2. Patents by formulation – i.e. the particular recipe you use to achieve something novel…

In the beginning DIAM had both of these. Today the patent for their formulation has expired – so anyone can chop up cork, mix it with adhesive, mold the two together to make something that looks like a DIAM. The patent for their process has not yet expired, so the use of supercritical fluids to remove impurities in the cork cannot (yet) be used by another manufacturer.

Summing up: The DIAM seals were marketed at the outset as being guaranteed free from TCA – no corked bottles – but they proved even more interesting as it became apparent that their tight production tolerances enabled significant control over oxygen transport to the wine, as the wine aged. No more was it necessary to accept the high-level of oxygen transport variability inherent in traditional corks.

The market for DIAM

In 2017, Burgundy was the biggest sales market – with 70 million bottles sealed by DIAM – and much more tellingly, according to DIAM, more than 75% of grand cru white in burgundy was sealed by DIAM in 2017 – a number which I still find amazing!

Champagne is now the second-largest market for DIAM in France. The 2017 sales of DIAM amounted to €42 million in France and €145 million globally – which equates to 1.8 billion units – Italy, America and Spain are also important markets.* Interesting in the context of 18.5 billion bottles produced in 2017, 12 billion of which sealed with ‘cork.’**
*Figures from DIAM – they also sell about 50 million units into the beer market.
**Figures from APCOR; The 12 billion number includes single-punched natural corks, ground cork, such as that used in Champagne and other sparkling wine stoppers, and cork discs – ground cork should include DIAM.

[Edit May-2020: Of course, the market moves on: In 2019 more than 1 million DIAM Origine seals (see below) were sold only in Burgundy – 3.7 million in France. Total unit sales for the company were 2.4 billion seals worldwide, 75% of sales are now outside France, bringing a turnover of €190 million. In 2019 Burgundy represented 15% of DIAM’s sales volume in France and 19% in value. They still maintain that 75% of white Grands Crus in Burgundy use DIAM.]

DIAM in action

This DIAM seal is different to a traditional cork, so it’s been shown important to modify the sulfur addition at bottling time. Typically that means reducing the dose of sulfur as the wine tends to be more reductive and less fruity.

Lack of TCA – the initial selling proposition of this technical seal – is, today, still important but not the main reason to buy or order DIAM when it comes to white wine. Empirically it is also an aid to avoiding oxidised wine – “I absolutely believe that the wines will be fine in 15 years,” says the representative for DIAM. It depends on the particular market as to whether purchases are more for whites or reds; Burgundy produces more white than red, so of course more white wines are sealed here with DIAM. My oldest references in red are the 2005s of Domaine Roger Belland – sealed with DIAM5 – and in 2018, the seal seems as when new and the wines are in good shape.

I refer you to the partner article to this, below, my telling tasting of Domaine William Fevre’s Chablis covering the vintages 2017-2006 – all DIAM5 sealed.

Arguments, sometimes philosophical, against DIAM

There will always be people who are opposed to new developments, whether that is because they have a financial connection to an ‘old solution’ or, possibly in this case, simply a philosophical rejection of an industrially produced product – ‘It’s not natural!

I have a high level of interest in the reports of those people who say that DIAM taints a wine, and that they can taste and identify the ‘bitter’ effects of a DIAM-sealed bottle – blind. Are they super-super-tasters? There seems only a single (German) source for this, which you may find on the internet. But I don’t actually know anyone who can do this – including winemakers – I certainly cannot. I may have the super-taster taste receptors for types of pyrazine (unlike much of the population), but ‘DIAM-bitterness‘ is missing from my arsenal. If this is truly a demonstrable, repeatable, effect, then it is important to know what proportion of people can taste or sense this, so as to judge the significance, but after nearly 15 years of sales there is no data…

[Edit May-2020: Over time, and very many bottles, I have noted that I can detect DIAM-sealed bottles, but specifically those bottled that have been sealed with no change in the sulfur regime that the producer used for normal corks. There is a typical – but unique – style of reduction that smells exactly like cornflakes. It is a phase that lasts for up to one year in bottle – or indeed 10 minutes in the glass – and then it is gone.]

DIAM Version 2 – Origine

So, if DIAM is not ‘natural’ enough for some consumers, enter their bio version – ‘Origine by Diam.’

Origine by Diam is described as being manufactured from products with an origin that’s ‘99% Bio.’ In this case, the polyurethane adhesive has been replaced by a blend of castor-oil-derived products and beeswax – and there are no plastic micro-spheres within. The Origine is the current choice of many domaines, including Chanson Père et Fils, Domaine des Comtes Lafon, Domaine de Montille, Domaine Méo-Camuzet and Domaine Taupenot-Merme. There is, of course, an extra cost attached to the Origine, about 35-45% more than the classic version.

[Edit May-2020: Additional domaines in Burgundy (partly) using Origine include in Chablis Olivier Savary, Daniel Dampt, Sébastien Dampt & Jean Defaix. In the Côte d’Or Vincent Dancer, Jacques Prieur, Château de Meursault, Château de Marsannay, René Bouvier, Jean-Marc Vincent, Olivier Lamy, Bruno Clair, Patrice Rion, Vincent Latour
Edit June-2020: I initially wrote rapeseed-oil, the company now tell me ‘castor-oil-derived’ …

The sulfur regime used at bottling has to be adapted (increased) versus the previous (standard) DIAM formulation as there is more air trapped within the matrix of the product*, but they assure me that there is an equivalent seal in the neck of the bottle.

*[Edit May-2020: Oxygen Initial Release (OIR): This means all the volume of oxygen, coming from the seal, going into the wine:
DIAM10 Origine and DIAM30 Origine bring 1.1 mg O2 per litre in 6 months.
DIAM10 and DIAM30: 0.8 mg/L
DIAM5: (the best seller in Burgundy) 1.3 mg/L
DIAM3: 1.6 mg/L
To compare, premium natural cork ranges between 2 and 10+ mg/L, after 6 months of bottling. (Revue des Oenologues – January 2019 – Véronqiue Chevalier, Christophe Loisel, Alexandre Pons)

Of course, for some people 99% bio won’t be enough. I assume that the same people turn a blind eye to the fact that there is also no 100% natural cork product available on the market; all corks undergo cleaning/washing processes and most are coated with either a paraffin-wax or silicone so that they can be properly inserted and more easily removed from bottles. The only (potentially) additive-free alternative might be a glass seal – but that in itself is an industrial product just like the bottles – there is no 100% solution.

From my own perspective, I can only think of one significant problem associated with a wholesale move of (particularly) white wine producers to using a DIAM seal; the importance of an ongoing search for a solution – or at least the cause(s) – to the extra (oxidative) sensitivity of today’s white wines might be forgotten if there is no-longer an oxidation problem for consumers…

[Edit May-2020: And for the future, I understand that ‘non-chamfered’ versions of the Origine are becoming the weapon of choice for higher-end producers – and I thought a standard, chamfered, DIAM was hard enough to re-insert into a bottle!]

Notes & Disclosures:
1DIAM Bouchage is part of the wine-production focused Oeneo group, together with the cooper Seguin-Moreau, Vivelys who supply (amongst other things) oak chips and micro-oxygenation systems, and finally a traditional cork producer called Piedade who mainly have locations in Portugal.
2I disclose one modest lunch with the representative of DIAM, in Beaune. He paid – but I drank only water and a coffee – as I had to drive to other appointments afterwards!
3I also disclose that I was invited to visit the DIAM factory. It would have been interesting, but given that I wanted to demonstrate some level of independence, I had to decline the kind offer. I could anyway learn what I wanted for this article by simply asking questions and tasting!
4Here’s an interesting web article with a Champagne perspective – judging by the photos, I assume the author accepted an invitation to visit the factory!
5After tasting all the following Chablis, I was once-more invited to lunch. I did drink one small glass of wine (a small one – I had to drive back to Beaune) and a coffee – again!
6Additional reading from Jancis Robinson – for your info.

William Fevre’s Chablis

Tasted with Didier Séguier in Chablis, 27 April 2018. Didier was very keen for me to be present when the bottles were opened to ensure that they were not picking and choosing bottles. The result here was 12 correct bottles from 12 opened.

William Fevre in Chablis and Bouchard Père et Fils in Beaune – both owned by Henriot of Champagne – began testing their first samples of DIAM in 2003, continuing in 2004 and 2005. Fevre changed all of their villages production to DIAM5 in 2006. They followed by bottling their 1er crus with DIAM in 2007 and the grand crus since 2010.

  • Petit Chablis & Villages Chablis use DIAM5
  • Premier Cru Chablis use DIAM5 except Vauloret and Montée de Tonnerre which use DIAM10 (54mm long)
  • Grand Cru Chablis use DIAM10 (54mm long)

A DIAM is (qualitatively) more homogenous than a normal cork – also more hermetic,” Says Didier. Due to the latter, not just the sulfuring regime has changed at domaines such as William Fevre, they have also changed their elevage a little – lengthening their elevage by about 1 month so as to ‘reduce any impact from reduction.’ The quantity of sulfur used at bottling has significantly reduced versus with normal cork; previously bottling was done with 35-40 mg of ‘free’ sulfur when using regular cork seals, today when using DIAM it’s just 25-30 mg of free sulfur at bottling time and that is constant regardless of whether it is a DIAM5 or a DIAM10 that is used.

My purpose for this tasting was not just to witness that a DIAM preserved wine from oxidation (TCA is a given), it was also to demonstrate – or not – that the wine would develop in a recognisable way towards maturity as I have previously experienced with white burgundy – rather than hold stasis as a ‘young wine.’ The perfect ‘test-mule’ seemed to me to be a pure villages Chablis. The chosen wine is the domaine wine of William Fevre – note that their ‘other’ villages Chablis, the cuvée Champs Royaux, is a négoce wine. This domaine wine was produced from 18-20 hectares of vines up until 2013 – 45 hectares thereafter – the additional hectares, all planted around the late 1960s to 1972 so described as Vieilles-Vignes though it’s not mentioned on the labels. Note that 2/3rds of the crop was lost to frost in 2016. There is some oak used in the elevage of this villages cuvée – anywhere between 5-10% – ‘Though nearer to 5% and never with new oak.’

And the result? – Mission Accomplished.
It seems demonstrable to me that wine sealed under DIAM does develop; this closure is not simply a hermetic ‘Band-Aid’ against TCA and oxidation. It also delivers what I want in terms of wine development – perhaps a little more slowly than a traditional cork – but you can decide for yourself if that’s a good thing or a bad thing. Anecdotally you might see a similar result from screw-caps too (EDIT: later, I did) – they are very popular in certain markets – but in Europe, at least, they remain rare for white burgundy; Benjamin Leroux being one of the few volume exponents of quality wine to use them. As for Nomacorcs, another technical seal, I have a very consistent level of disappointment in the result – all my 2007 Alsace grand crus were oxidised with this seal, reinforcing that this is not just a Burgundian problem.

Normally it’s a longer elevage for this wine, but not in 2017 – this was bottled only two weeks ago and that’s early because they have no wine after such a small volume in 2016! But that’s only the case for the Chablis and the Petit Chablis – the rest of the range saw the usual elevage.
A nice width and impact of aroma here, pretty notes of fresh precision and an unsubtle floral too. Round, a hint of richness, floral-infused delicious wine. A lovely finishing line of fresh apricot – really a classic and pretty wine – simply excellent!

Just a little narrower aromatic and more serious too but also a nose with a fine depth. More concentration, more layered, an extra salinity – more serious intent here. In the flavour too there’s more depth – it will last longer than the 2017 but you may also have to wait longer for it to come round! Super tasty wine if less overtly delicious and fresh as the 2017 today – but the better wine I think, and with such a great and open finish too!

A little extra twist of ripe lemon, a lovely line to the aroma too. Fine width, beautifully textured but balanced, again a hint of salinity and some lovely, slowly moving waves of delicious flavour – more in the style of the 16 than the 17 but with more open minerality today than the 16. Super wine again and much more classic and less rich than the general reputation of this vintage.

Hmm, this has a super nose, more mineral and hyper-attractive, but still baby wine. Ooh a core, a line, of vibrancy here – dynamic, complex – playing over the palate – great and intense villages! Super finishing too. No notes of maturity yet.

Hmm, wow! That’s just so different, more ample and rich, a tiny reduction too. Hmm, at the start there’s almost a metallic side to the acidity – but a super acidity and the metallic aspect fades. An extra richness of texture but a wine that’s very mouth-watering – put those aspects together and that’s really a super balance. Mineral and long this is a little out of character with the previous wines but no less delicious and with a super impressive finishing intensity – always a reductive style to this tasty wine.

‘Some people harvested a bit late in 2012, outside of the that it’s simply a great vintage,’ notes Didier.
A ripeness and weight but at the same time there’s a freshness of agrume aroma – I buy shower-gel that smells like this! The colour is still that of a baby. Hmm, that’s concentrated, it’s also layered, mineral and delicious in the mouth – almost a little more muscle than the 2014 – this is another great villages. I love the finish with its complexity and brightness yet always an energetic purity! Great villages wine.

A really early harvest for these vines – 31 August!
Hmm, the colour is still young but for the first time there is some development to the aroma – it’s nicely vibrant at the core too – a little, but not overtly vegetal or showing asparagus as in many 2011s – practically it’s a light pyrazine. In the mouth it’s round, fresh mineral a hint of asparagus here. But the intensity, shape, line and texture are more compelling!

Still baby colour. Lots more flowers on this nose – fine depth, just commencing is a little extra aromatic complexity from the age. Hmm, a little reductive, mineral, vibrant, with cushioned freshness and layers of finishing flavour – together with 12 and 14 a great wine – and really just starting to offer the creaminess of finishing flavour that comes with a little age. Just a brilliant, pure and mineral finish.

Starting to show a little extra depth of colour – more golden. A little less width of aroma but a depth of ripe fruit and complexity – a little reduction here too – the nose evolves in the glass, growing and filling the bowl. Hmm, richness of silky texture, depth of flavour but balanced with the steely minerality and faint salinity. This is great – and so large-scaled – and really beginning to show some degrees of maturity – excellent! Super finishing and this is the first wine that’s showing a little creaminess of maturation in the finishing notes. Despite the vintage there is tension here and there is also 1er cru concentration here – bravo for that!

Almost a hint younger colour than the 2009. Directly a classic nose of 2008 it’s in the direction of 2011 but less vegetal and riper with a fine complex freshness – ‘Yes – this vintage is more about maturity by concentration than physiological maturity.‘ says Didier. But it’s a big and quite captivating nose, growing in floral complexity in the glass. Also a beautiful texture, it’s a richness but not to the level of the 09. Wide, complex, delicious and absolutely energetic – brilliant – and it’s only possible in Chablis this finishing flavour. Excellent here in the finish – easily the best part of this already super wine!

There is some age to the colour – more gold than yellow. Oof – we have maturity, complexity, a hint of creamy aroma too – bravo! If only I could buy this wine now! Complex, deep, fresh – a wine of line and minerality, of energy too – it’s just an all-round bravado performance. Great villages and it’s ready for you – exceptional stuff. Great finishing too. It starts narrow and just gets wider, wider and more compelling. Didier: “This was a little meagre when young, it lacked some volume though always had lots of acidity – but after 11 years it’s a purist’s wine…

Actually a little younger colour. Wide, vibrant, mineral – it’s a compelling nose – the grail of Chablis – a fabulous nose. More roundness more volume, still lots of energetic freshness – actually this is also super, far exceeding my expectations of this vintage; persistent a little cream, vibrant flavour – it’s a great finish again. And here are the first proper aged notes as opposed to notes of maturity. It’s a great finish.

Agree? Disagree? Anything you'd like to add?

There are 2 responses to “DIAM and the eventual triumph of empiricism…”

  1. Fred Schilling2nd June 2018 at 4:59 amPermalinkReply

    I agree, Bill, that technical corks, such as DIAM (and DIAMANT for sparkling wine), are a very good but still second best solution. DIAM corks have been made to be TCA free with standardised dimensions and density/compressibility but that still leaves a variable bottle neck bore diameter within a defined acceptable tolerance range to interact with that technical cork. There will inevitably be a maximum allowable bore diameter fitted with a minimum diameter cork.

    Experience down here in Oz and NZ, from the viewpoint of a serious consumer, has continued to demonstrate that screwcaps, with selective oxygen transmission rates (if you think that’s important), provide the best and most consistent wine bottle closure at present. Screwcap is equivalent to “best cork”.

    Premox has never been just a white burgundy problem. While “ancient” wine drinkers like me have put up with variability from multiple bottles of the same wine, purchased at the same time, stored side-by-side over years, with a shrug of the shoulders on the basis that “there aren’t any great old wines just great old bottles”. I believe that today’s wineries, with current scientific and engineering knowledge, owe a duty to purchasers and their own reputation. Not to mention all the great wine that is unnecessarily destroyed.

    In any case, if all Burgundian wineries changed to DIAM corks that would be a great thing. The next step in France to more universal use of screwcaps will come in time. Why not seek out the long term knowledge and experience from antipodeans? There’s no need to reinvent the wheel in order to determine the required changes to bottling chemistry in transitioning to screwcaps.

    Very Best

    • billn4th June 2018 at 1:47 pmPermalinkReply

      Interesting. Thanks Fred.
      Whilst I note in my text that screw-cap may be just as efficient, it is laregly not possible for me to empirically say that because they are so rare in Burgundy – Benjamin Leroux being one of the (currently) rare exceptions. JC Boisset went down the route of screw-caps for the 2007 vintage – provocative said the syndicat of Gevrey producers, because the winemaker chose to screw-cap Chambertin! I tasted a white from that batch last year and it was excellent. Unfortunately it didn’t work out for them as the market didn’t accept them – so what is a producer to do? People, myself included, are still quite attached to their corkscrews and DIAM has more acceptance – perhaps – because of that.

      I have to challenge your ‘second best’ only because it has to be something statistically relevant – what is the failure rate of DIAM due to bottle neck bore diameter variance? If it’s one in a thousand – and I’ll be surprised if it’s more (though am prepared to be corrected) – then I don’t see that as statistically relevent. The counter-argument from the ‘anti-screw-cap’ brigade is that screw-caps are fragile if knocked – who knows(?) – but DIAM does work, and I suspect screw-caps too, but as noted I don’t have the same empirical evidence…


  2. newmanja7713th June 2018 at 11:00 pmPermalinkReply

    Bill – I thoroughly enjoyed this review and I agree I am very happy to see the transition toward more DIAM corks. Thanks for the information regarding the construction of these corks as I only had a general idea. Also very pleased to see some older tasting notes from these closures as I have always wondered how they would hold up. I’ve had red pinot noir from Oregon bottled with DIAM back to 2010 and have found them successful, but nothing older. Also good to see that the bottle age doesn’t create the “glue/bitterness” taste that some people claim as there has been the theoretical concern regarding long contact with wine as a solvent. Thanks for the article!


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