For a long time I have wished for something better than natural corks to protect the wines I made. The problems with natural cork are twofold. The first and worst is that at least 1-2% are tainted with mold flavors which gets into the wine. The second is that the porosity of corks to oxygen is variable over a three fold range, so the individual bottles of wine age at a random and unpredictable rate. For most of my thirty years as a winemaker there has been no viable alternative to natural cork. However, a few years ago a French company made some crucial improvements to an earlier product that made for a real improvement over natural corks without sacrificing any of the many good things that have made corks the standard choice for a few hundred years. The product is called DIAM and it is made by grinding up cork, stripping all of the aromas out of it and then molding it back together with polyurethane. This type of cork, (which is termed) "agglomerated," has been used for some time. All Champagne corks use this technology. The two things that make DIAM superior are that the cork has been neutralized flavor wise and that the plastic binding material has been designed to breathe slightly so that the tiniest amount of oxygen flows through the cork and helps the wine age. With this said, Tolosa Winery has now made the decision, which seems so clear to protect our product, that all vintages beginning in 2008 will be with a DIAM cork, except for our screwcap closures.

We have chosen to use the DIAM cork for our closure. DIAM is made from the "noble" component of natural cork treated with the patented Diamant process, a supercritical carbon dioxide process which basically eliminates TCA contamination of the wine and over 150 trace elements. Multiple tests verify that the DIAM cork is completely neutral to wine which means it will not alter the taste. It also maintains consistency in terms of permeability and decreases variability between bottles. It retains its shape well to prevent leakage and it is easily removable. In addition, the DIAM cork is a recyclable, renewable and biodegradable resource.

After seven years of intensive internal research for alternative methods of closure, we have decided to use "DIAM" corks for an important part of our classic range of wines of the 2006 vintage. We have always observed — and this phenomenon is widely known in our profession as one of our main quality issue Ð that a fraction of the wines sealed with natural cork suffer from what is generally called "cork taint." In fact, this phenomenon seems to have become more marked in recent years, and so in 1998 we began to seriously investigate ways of overcoming the problem. We studied and experimented with every different type of "cork" that existed on the market (agglomerated, treated, synthetic, 1 + 1 (composite), and screw-caps. After countless tests conducted with great rigor by Marc Hugel as well as a recent 4 day visit Oeneo's premises in Spain we have finally selected DIAM. This type of cork uses several new techniques:

Extraction of suberine (the "noble" component of natural cork) and elimination of lignine (the "woody" component)
Treatment of the suberine by supercritical carbon dioxide (patented process) in order to eliminate practically all the TCA which causes the bad taste known as "cork taint".
Assembling the suberine with a binding agent to give each cork a homogeneous structure and perfect neutrality. In other words, in fact, this type of cork has a triple advantage : it is neutral to the wine (that is to say, it is not able to transmit any bad taste to the wine). Thanks to its 100% homogeneous structure, which guarantees a perfectly normal rate of evolution in the bottle, without the variations encountered previously, we are assured of optimum aromatic freshness in half-bottles of our wines. it ensures (and this is an added bonus) that every cork is identically easy to extract, in fact less strength is needed than before (about 25 kg against 20 to 40 kg for a normal cork and 45 kg for a synthetic cork!), making cork-pulling particularly "comfortable."

The DIAM cork is the result of long years of research by the Oeneo-Bouchage company, and has obtained numerous awards and gold medals at professional wine shows. For the past seven years we have tested this cork with great success, which has given us sufficient experience to make this choice with every confidence. Each "DIAM" cork that we will use will carry in addition of our traditional marking, the web address of our Internet site in order to inform our future users of the virtues of this new product.

“While I was very hesitant, OENEO lobbied me for a while to perform a trial with their new product, DIAM. I was very impressed by the commitment and efforts they undertook to make improvements in an agglomerated closure so I initially bottled a few dozen cases, out of curiosity and more as a favor than anything else. But there came a time when I needed to do a meaningful trial so we decided on one hundred cases. I am very impressed with the initial result. I have never liked nor used synthetic corks and have worked extensively with screw cap closures, which I do not like at all. So for me and my wines, DIAM represents a good compromise between quality, cost and ‘natural’ aesthetics. I am hopeful the ongoing QC will reveal outstanding performance.”

"At Cosentino Winery we produce more than 35 different wines and technological closures have been used with great success on various projects. We used the DIAM cork in two different bottling runs as trials with no failure of closure and no off flavors detected. We look forward to increasing our use of this closure due to the excellent results seen. This closure not only offers great price but peace of mind for our winery.”

One of the real concerns over alternative closures and one of the reasons Domaine Georges Michel has not chosen screw caps is that fine wines need to age and develop in the bottle over time. Part of this process is a very small ingress of oxygen through the cork allowing the wine to expand and age successfully. Screw caps in particular don't allow this to happen and the wines age in atypical ways and can be affected by "reduction" (off smell).

Corks and DIAM corks allow a small amount of gaseous exchange resulting in the typical aging characteristics we are all familiar with. DIAM has been rigorously tested, technically certified by independent laboratories worldwide and has won international acclaim and awards.

Many of the world's most respected still and sparkling wines are now sealed with DIAM. We're sure you've heard of Moet & Chandon, Louis Jadot, Mission Estate, Stonecroft, Tyrrell's, Tempus Two, and of course our winery. In fact over 500 wineries in Australia and New Zealand have chosen DIAM to seal their premium wines and the number is growing daily.

Bottle variations are also no longer a topic of conversation at the dinner table for wines sealed with DIAM. We have chosen to use DIAM to ensure each bottle is delivered to you in the best possible condition for your enjoyment.

The DIAM corks used in our wines, like traditional corks, protect the wine and promote proper aging over time. Since switching to our new corks, we have yet to have a single bottle of our wine returned due to cork taint, nor have we discovered a corked wine in the tasting room.