In the Thick of the Oak Forest

JPV’s WINEMAKER VISITS THE ANCIENT WOODS OF FRANCE
By Ashley Hepworth

I am fascinated with oak used for barrels and the craft of coopering a barrel.   In February 2009 I had the incredible opportunity to join a group of winemakers in France with one of our barrel companies Tonnellerie Sylvain.  The week began on the right bank of Bordeaux in Libourne where the seasoning yard, stave mill and cooperage are located.  The trip concluded in one of the main forests where they purchase wood, the Tronçais forest.

Jean-Luc Sylvain transformed his father’s barrel maintenance business, which began in Libourne in the mid 1950’s, into a world class cooperage in the early 80’s. Today Sylvain is a staple barrel among the top chateaux in Bordeaux, world class wineries throughout Europe, the Napa Valley and the Southern Hemisphere.  The cooperage produces around 30,000 barrels per year. The attention to detail I witnessed, including the passion, knowledge and tenacity that Mr. Sylvain has for each phase of the barrel making process is truly admirable.  He gathered his wealth of knowledge from hands-on experience beginning with understanding the most important part of the barrel making process, which is sourcing the oak.

Jean-Luc Sylvain at the entrance to the Tronçais Forest.

There are many beautiful oak forests in France, most of which are owned by the government, supervised, protected and preserved by the Forests National Office (ONF).  French oak used for barrels comes from an assortment of forests in different regions which contain different species of oak as well as different growing conditions and thus different grain widths.  All of which are important to the winegrower and the type of wine they wish to age in barrel. 

Tronçais is located in the center of France in the Allier Department (west of Burgundy).  The forest covers approximately 26,500 acres. In 1327, part of the forest was given away to the Bourbon lords and in 1528 it was confiscated and became part of Charles III, Duke of Bourbon’s assets.  Then in 1670, during the rule of the “Sun-King”, Louis the XIV directed Jean-Baptiste Colbert (his minister of finance) to perform a detailed exploration of the Tronçais forest, marking boundaries and creating parcels while promoting seedlings in order to anticipate future wood needs for the construction of shipping vessels.

In the late eighteenth century a major part of the forest was managed by Lord Rambourg who supplied the forge located in the forest.  Currently the Tronçais forest is divided into three parts.  The first part is approximately 24,500 acres of straight standings with a regeneration period of around 200 years for carpentry wood (6,000 acres) and 250 years for the wood that is used by the cooper (18,500 acres).  The second part is approximately 1,120 acres of pine trees with a regeneration period of around 100 years.  The third part is dedicated solely to leisure space.

The life cycle of a parcel in an ONF-managed forest begins at the germination stage and follows through to the pole stage, perch stage, young futaie stage, haute futaie stage, sowers and finally the harvesting.  The germination stage occurs with seedlings from sowers which are the straightest in the parcel and are the oldest and the last to get harvested.  The acorns establish themselves in the forest floor and when there is sufficient sunlight penetration around the sowers being harvested, the seedlings become very thick; typically there are hundreds of thousands per acre.  The ONF will intervene by eliminating competitive species and help clear any weak seedlings.  The pole stage is when the tree reaches about 15-30 years old. Competition is fierce during this stage and natural selection takes place in addition to the ONF intervening by clearing out brush to promote growth of the straightest and strongest trees.  The straighter the tree and the higher up the branches start, the more wood can be used for barrel making.  When an oak tree reaches approximately 40-60 years, this stage is referred to as Perch, and continual natural selection and the watchful eye of the ONF takes place.   At this time the strongest and straightest trees with branches starting high on the trunk are marked for sowing.

Haute Futaie

At the century mark, the young futaie has reached its maximum height which can be around 80-100 feet. The diameter at this time is approximately 12 inches and will continue to grow over the next hundred years.  Haute futaie is the reference name given to the tree at around the 200 year mark.  This is an important time because the growth of the tree slows down and selected cuts are conducted over the next 20+ years by the cooperage/carpentry industries.  The best sowers are allowed to seed and are finally harvested during the definitive cut (last cut of the parcel) and the process begins all over again. Within each plot the trees are about the same age, although an adjoining plot could be 200 years older than its neighboring plot, which reaffirms the constant re-generation taking place.

The strongest and straightest trees are called “sowers.” This sower is over 250 years old.

October is a very exciting time for the cooper/saw mill owners because tree auctions take place.  Coopers bid on parts of parcels that they have already had their eye on; thanks to the organized ONF that sends out a book describing each part of every parcel in each forest including the tree measurements that will be up for auction.  The cooper and the saw mill owner are typically working together for the bidding because only about 50% of the tree (“the merrain”) will be able to go to the stave mill for coopering.  The balance of the tree goes to the saw mill owner for carpentry wood.  They are mutually interested in quality primarily and price secondarily.  They decide what they will bid on jointly, which means they have already gone together to the plots of interest, re-measured diameters and eyed the height and the amount of usable wood between the two of them.  After the auction lots are obtained, cooper and saw mill managers will organize the felling of the trees during the winter months.  The trees are measured again once felled to determine exactly what part of the tree will go to the stave mill and what will go to the saw mill.  Trunks are organized with the name of the cooperage and a reference number tracking back to the exact tree location in that plot and then transported to the cooperage.  After two days of studying the forest, seeing the regeneration and watching trees felled, I felt obliged to ask Mr. Sylvain how many acres of the Tronçais forest he thought he had used in his cooperage over the past 29 years. His response was he could be within a few parcels in one small area of the Tronçais forest and spend his whole life buying wood just from this area.

Just harvested merrian

The two species of French Oak that are of interest to the cooper are Quercus sessiliflora (referred to as sessile oak) and Quercus robur (referred to as pedunculate oak).  In general, sessile oak produces straight trees with branches starting high up the trunk and usually with tighter grain.  Pedunculate oak typically has branches which are more spread out and begin lower on the trunk and produces wider-grained wood.  There has been quite a bit of natural cross-fertilization over the years between these two species.  Relatively speaking the Tronçais forest is predominately sessile oak.  However, the most important factors are the grain width and in which area the tree was grown.

Winegrowers might choose a tighter grain, thin stave barrel (22 mm thick) for more oxygen ingress during the wine aging (traditional for aging Bordeaux varietals) or a wider grained barrel with thicker staves (27 mm thick) for less oxygen incorporation (traditional for Syrah, Chardonnay and Pinot Noir).  Think of the grains as a bunch of straws on end: the more straws, the tighter the grain and the more oxygen ingress will occur during aging; fewer straws, the wider the grain and less oxygen incorporation. 

At the cooperage the logs are split into staves, sanded and stacked loosely on top of one another in a lattice pattern on a pallet for open element seasoning (air, sun, wind, rain, etc.).  Logs yield approximately 8-16 barrels; it really depends on the size of the merrain as to how many barrels a tree can produce.  Seasoning at Sylvain is approximately 36 months during which time enzymes form to break down coarse wood tannin creating softer more complex compounds including delicate aromatics.  The longer the seasoning takes place the less harsh the oak flavor profile will be. Typically French oak barrels are aged for 24-36 months, most of the barrels for Joseph Phelps Vineyards are aged an average of approximately 36 months.  During the seasoning the stacks of wood on each pallet are sometimes restacked in order for the bottom layer to get shuffled to the top layer and vice versa to ensure homogeneity.  After the seasoning period the staves are re-sanded and the barrel building and toasting process occurs. 

Barrel toasting.

Toasting is a cooperage specialty; one cooper’s “heavy” toast barrel could be what another cooper calls “medium plus” toast which is all dependent on the amount of time and the temperature during toasting. Therefore it is up to the winegrower to decide what they prefer for the wine they are making: Tronçais wood, tight grain, thin stave, heavy toast, 24 month seasoned, etc. The possibilities are numerous.  The crafting and toasting of a barrel take just a couple of hours.  Then barrels are ready to get wrapped up in plastic and shipped to the winegrower.

Cooperages, like natural cork companies, are performing intensive haloanisole* testing on their products throughout the processing stages including raw wood, seasoning and also the transportation vessel, which ensures the customer a wood product is certified free of TCA.  Cooperages are being watched heavily at the moment because the French government has launched an audit to make sure that the origin of the wood and seasoning time that the cooperage state are truthful.  Indeed, the French government found that some cooperages that were advertising and selling barrels under one specific forest were cutting corners by substituting expensive single forest staves with less expensive and lower quality staves, sometimes of Eastern European origin.  It is now commonly known among winegrowers that if you want a barrel that is 100% from one specific forest, you may ask the cooperage for the complete traceability of the wood origin and length of seasoning. They are obliged to furnish this information to the customer. 

At Joseph Phelps Vineyards we enjoy using some specific single forest barrels for our wines, but mostly we are concerned and focused on working with reputable cooperages and with the grain selection that we desire for the wine being aged.  Most of the oak barrels we use are  tight grain, and from forests in the center of France, which means that the grain selection is the key factor here and the wood is sourced not just from Tronçais but from other forests that all have similar grain width and similar quality levels.  Some other forests popular for tight-grain selections are Bertranges, Belleme, Berce, Loches and Sarthe.  Sylvain barrels are a blend of a handful of different forests, but to Mr. Sylvain the most important factor is that the wood is of the best quality, has a tight grain, is seasoned properly in the open air with the elements and the toasting is done watchfully so that they deliver a consistent product year after year.   At Joseph Phelps Vineyards, we work with approximately fourteen different cooperages each of whom we have worked with for many years.  We have developed close relationships with these cooperages which is extremely important.

This in-depth understanding of the Tronçais forest has broadened my understanding and respect towards oak sourcing, regeneration of the forest and the time it takes to create a barrel that will be used to age our wine from trees over 200 years old.  

*Haloanisoles are chemical compounds that convey a musty, moldy or dirty aroma in wood products or wine. They are formed when fungi make their environment less toxic to them by breaking down the haloanisole precursor. The most common wine haloanisoles are TCA (trichloroanisole) and TBA (tribromoanisole). TCA is commonly described as “cork taint.” Either spoilage aroma can be found in most natural products that contain phenols including barrels, barrel containers, natural corks or wine.