<P> New barrels impart more flavors than do previously used barrels . Over time many of the oak properties get "leached" out of the barrel with layers of natural deposits left from the wine building up on the wood to where after 3 to 5 vintages there may be little or no oak flavors imparted on the wine . In addition, oxygen transport through the oak and into the wine, which is required for maturation, becomes severely limited after 3--5 years . The cost of barrels varies due to the supply and demand market economy and can change with different features that a cooperage may offer . As of late 2007 the price for a standard American oak barrel was US $600 to 800, French oak US $1200 and up, and Eastern European US $600 . Due to the expense of barrels, several techniques have been devised in an attempt to save money . One is to shave the inside of used barrels and insert new thin inner staves that have been toasted . </P> <P> Barrels are constructed in cooperages . The traditional method of European coopers has been to hand - split the oak into staves (or strips) along the grain . After the oak is split, it is allowed to "season" or dry outdoors while exposed to the elements . This process can take anywhere from 10 to 36 months during which time the harshest tannins from the wood are leached out . These tannins are visible as dark gray and black residue left on the ground once the staves are removed . The longer the wood is allowed to season the softer the potential wine stored in the barrels may be but this can add substantially to the cost of the barrel . In some American cooperage the wood is dried in a kiln instead of outdoor seasoning . While this method is much faster, it does not soften the tannins quite as much as outdoor seasoning . </P> <P> The staves are then heated, traditionally over an open fire, and, when pliable, are bent into the desired shape of the barrel and held together with iron rings . Instead of fire, a cooper may use steam to heat up the staves but this tends to impart less "toastiness" and complexity to the resulting wine . Following the traditional, hand worked style, a cooper is typically able to construct one barrel in a day's time . Winemakers can order barrels with the wood on the inside of the barrel having been lightly charred or toasted with fire, medium toasted, or heavily toasted . Typically the "lighter" the toasting the more oak flavor and tannins that are imparted . Heavy toast or "charred" which is typical treatment of barrels in Burgundy wine have an added dimension from the char that medium or light toasted barrels do not impart . Heavy toasting dramatically reduces the coconut note lactones, even in American oak, but create a high carbon content that may reduce the coloring of some wines . During the process of toasting, the furanic aldehydes in the wood reach a higher level of concentration . This produces the "roasted" aroma in the wine . The toasting also enhances the presences of vanillin and the phenol eugenol which creates smokey and spicy notes that in some wines are similar to the aromatics of oil of cloves . </P> <P> Although oak barrels have long been used by winemakers, many wineries now use oak wood chips for aging wine more quickly and also adding desired woody aromas along with vanilla flavors . It is a common misconception that oak imparts butter flavors to wine . This is not so . The butter flavors come from lactic acid, naturally present in the wine, converted during malolactic fermentation to diacetyl . This process reverses itself, although the addition of sulfur dioxide prevents this, and the diacetyl remains . Oak chips can be added during fermentation or during aging . In the latter case, they are generally placed into fabric sacks and placed into the aging wine . The diversity of chips available gives winemakers numerous options . Oak chips have the benefit of imparting intense oak flavoring in a matter of weeks while traditional oak barrels would need a year or more to convey similar intensity . Critics claim that the oak flavoring from chips tend to be one - dimensional and skewed towards the vanilla extract with the wines still lacking some of the physical benefits that barrel oak imparts . The use of oak powder is also less common than chips, although they are a very practical alternative if oak character is to be introduced during fermentation . Oak planks or staves are sometimes used, either during fermentation or aging . Wines made from these barrel alternatives typically do not age as well as wines that are matured in barrels . Improvements in micro-oxygenation have allowed winemakers to better mimic the gentle aeration of oak barrels in stainless steel tanks with oak chips . </P>

What does it mean to be an oak