Of the many different aspects that affect the finished product of a wine, oak wraps it all up. Literally. Oak barrel fermentation not only differs according to the type of wood used, but the fermentation process is also highly affected by the “toast” amount.
American oak mostly comes from the Eastern part of the United States such as Missouri, Minnesota, and Wisconsin. French oak comes from five major forests throughout France. Cooperages (i.e. barrel making houses) receive the wood logs, cut along certain lines, and then shave the pieces into thin staves. They then assemble each wood slat into a barrel form, place the barrel over a burning fire or take a blow torch and “toast it”. This step closes the gaps between the slats- once they pump the wine into the barrel no one wants any of the precious liquid to seep out! The interior of the barrel is charred with a “light”, “medium”, or “heavy” toast depending on the winemaker’s desired level of oak flavor. You can see in picture at the top featuring the different levels of charred oak staves.
Compared to American oak which typically gives off stronger flavors with hints of vanilla, French oak has a tighter grain and therefore has a less “oaky”, more subtle flavor. As of late 2007, a standard American oak barrel cost around 500 USD whereas a French oak barrel cost around 1,000 USD. Barrels are typically used two, maybe three times total. Also, they are only used with “like” colors. For example, you wouldn’t use a barrel that previously had red wine in it for making a white wine the following year because the red wine would have left a stain that could taint the white wine, turning it slightly pink in color.