The Diam closure – now and in the long run

The Diam closure is now used by many of the top producers of white and while this has or is expected to eliminate the premox problems some collectors are still sceptical about this new closure – I for one want to learn more about the long term effects of using Diam instead of natural corks.

Interview with Didier Séguier of William Fevre

I had the the pleasure of interviewing of Didier Séguier of William Fevre about their experience with the Diam closures. Bouchard Pere et Fils and William Fevre were some of the first to work with Diam closures back in 2003 and 2004 – the third estate that began then was Hugel in Alsace – so no estates have more experience with the longer/medium term effects of using Diam instead of natural old school cork.

Photo Didier Séguier – source Domaine William Fevre

It should be noted that William Fevre is owned by Henriot as is Bouchard Pere et Fils in Beaune – and the winemakers – Philippe Prost (until 2014) the winemaker at Bouchard and Didier Séguier at William Fevre have undertaken extensive tests with Diam from the very beginning when the closure was introduced in 2003.

So William Fevre has 13 years of experience in working with Diam – first for testing and later for commercial bottling. This means that they now have seen what happens when the wines are cellared and matured for more than 10 years with a Diam closure. They are still able to follow the development even with further ageing – and will in due time be able to see what happens when the wines are aged for 20 years or more.

For me these experiences are very important for the collectors of white Burgundies, at least those who like o drink fully mature wines – i.e. 20 – 30 years of ageing depending classification level.

The different types of Diam – a short intro

Diam make several different closures – Diam 5 and Diam 10 are used by William Fevre, the Diam 5 for the Petit-Chablis and Chablis, whereas Diam 10 is used for the rest of the wines.

Diam 5 will let through more oxygen (higher permeability) than the Diam 10 and even to a higher degree than Diam 30. The Diam 5 is used for the lesser wines, as these will be consumed fairly early, and this will ensure some ageing on bottle with the higher permeability of the Diam 5.

The Diam 10 are used for the wines that need longer ageing, as this is believed to give a good and stable ageing in the longer run. Diam 30 is not used by William Fevre and is the closure that will – all other things being equal – give the slowest ageing on bottle as this according to the Diam homepage has the lowest permeability.

The William Fevre use of the Diam closures

Fevre first started experimenting with the Diam closure in 2003 and then began bottling its Petit Chablis and Chablis with Diam 5 from the 2005 vintage.

William Fèvre began using Diam 5 for its premier cru Chablis from the 2007 vintage.

From the 2010 vintage all the Grand Crus have been bottled with the Diam 10 closure, and these closures are now also used for the Chablis 1er crus.

The free sulphur at bottling has been reduced in two steps. In 2010 the free sulphur was reduced from 40 mg/l to 35 mg/l, and again in 2015 from 35 mg/l to 30 mg/l.

The experience from using Diam

According to Didier Séguier the William Fevre experience is that the wines age quite normally using the Diam closure – perhaps a bit slower depending on the type of Diam closure. The premox is prevented, and when the open a number of bottles with Diam corks from an older vintage the quality and the development of the wines is very uniform and stable – whereas if the open a number of bottles of a wine bottled with natural corks, there will be much greater variation in quality and some wines will perhaps show different degrees of premox.

So the experience after 13 years of testing is that it prevents premox, and the wines age well but perhaps slightly slower with the Diam closure.

The experience is that the wines with Diam closure show much better than the wines with screw cap. These are the observations done by William Fevre in Chablis – and hence not necessarily consistent with what producers have seen in other ares of the world.

It is important to notice that the development in bottle using the Diam corks is affected by the amount of SO2 used during vinification and bottling. Furthermore the type of Diam determines how fast the wine develop / age in bottle.

The level of SO2 and the Diam cork

The level of SO2 is very important for conserving the wines and preventing premox – with Diam there is however no or minimal variation in the closures – and lesser permeability i.e. oxidation though the closure.

William Fevre has now reduced the level of SO2 at bottling with 20% from 40 to 30 mg/l as a consequence of using the Diam closure. This is to get a balanced development of the wines – the Diam cork will give a slower development on bottle, but compensated with a lower level of SO2 this will ensure that the wine ages on bottle – at a fairly normal speed.

If the level of SO2 is maintained one could see that the wines will develop quite slowly after changing to Diam … if directly compared to a wine bottled with a natural cork.

Again it’s important to note that Fevre has worked with this for now 13 years – Bouchard for 14 years – and they are now able to see the medium to medium-long term effects of using Diam.

Fevre and Bouchard are still experimenting

Didier Séguier explain that both Fevre and Bouchard are doing continued experiments to improve the solutions – and they are not so to speak married to Diam – but for the moment this is the best solution offered and tested.

In the ideal world they would love to go back to using natural corks, but this is not viable currently as they cant accept the fact that some wines would then be affected by premox. The current solution ensure that the collectors get a high and uniform quality without the imminent risk of having a premoxed wine.

Summing up the Diam discussion

The Diam closure is the route that most top end producers seems to take in the fight against premox – and for me this is both understandable and needed – there are really little or no alternatives it seems.