Hi Gonçalo. I completely missed your question! And it’s a great question.goncalo devesas wrote: About the casks, I read that the best oak casks, are the one´s that are smoked for 3 years and in each year they lose 1 to 2 cm thickness and the oak that they use come from trees with a century, the price of each one, around 750/800 US dollars...
The casks we use to age the wines are made of Oak. Many of them are +50 years old and although I don’t think they lose 1-2cm a year, the staves need to be replaced now and then. Maintaining the some 3,500 barrels in the Graham’s lodge is a tremendous amount of work that can only be done by highly skilled craftsmen trained in the art of barrel making. The importance of barrel ageing to the quality and style of Port is such that the Symingtons have a full team of tanoeiros (the Portuguese term) working year-round, the last of its kind in the Port trade that I know of. Every one of the barrels is checked each year and repaired as needed. Nearly all of the work is done by hand, using the same hand tools as would have been used 100 years ago - it’s amazing to see.
You stirred my curiosity so I did some digging and thought I would share the details and history of the barrels with you.
During the 19th Century oak originating from Memel and Stettin in the Baltic was used for maturing Port, and towards the end of the Century and the early part of the 20th Century oak from New Orleans in North America was also favoured (Mardi Gras Port?). In 1932 Stettin oak became cheaper and many shippers began to use it extensively once more for their casks in the place of New Orleans oak. This supply from the Baltic dried up with the outbreak of the Second World War in 1939.
After the war Carpathian oak of the same type was obtained from Yugoslavia and more recently from the forests of Limousin and Allier in France.
Oak Casks have always been used in the ageing of Port as the permeability of the wood permits a gradual and controlled oxidation of the wine. Oak's tighter grain reduces evaporation and permits a slower and more controlled oxidation. Thus during the early part of the 20th Century when most Port was still shipped in cask, oak casks were used for maturing the Port while cheaper and more structurally robust chestnut casks of Italian, and Portuguese origin were used for shipping.
It is important to note that in the case of Port the new oak characteristics are undesirable, and therefore the casks must be extremely well seasoned (normally with red table wine so as to remove any wood flavour) before being put into use.