Ganga wrote:...It would pick up the same characterists as bourbon would from new oak. Vanillas for example. However, one must remember that the grain that is used for the distillate is different and these grains do provide a different flavor profile... If you want bourbon notes to stand out in your malt, get one that was fully matured in ex-bourbon casks.
This is also the way I see it.
Remember, toasting not only increases the superficial porosity of the staves, it also precipitates several key chemical changes in the nature of the charred surfaces. Lignin, an essential strengthening component of wood, yields two noteworthy methoxyphenols, guaiacol and syringel, when burned. Guaiacol is the component that possesses a distinctive vanilla-like taste. Furthermore, oak lactones, which occur in more concentrated form in North American white oak, offer up wood and coconut nuances. But these characteristics will be transfered to whatever spirit is matured in such a barrel.
However, when the original contents are emptied and another spirit introduced, as occurs when an ex-Bourbon barrel is filled with Scotch whisky, the Scotch whisky maturing in such a container will benefit from the type of oak as well as from
the residual influence of the original contents. Subsequent refills will, of course, diminish the effects of both wood and prior liquids.
So perhaps we need to more clearly delineate between 'Bourbon characteristics' and 'American oak characteristics'.