[Pontiac]

But it would only work, it seems, in bourbon. In the ACS Nano paper, Carrithers and his team report that the same sort of distinct webbing does not develop in scotch, nor in Canadian whiskies.

My first thought on this is that this distinction must be due to the fact that Bourbon must be aged in virgin American charred oak barrels.

This something unique to Bourbon. The oils in wood of the oak will be altered chemically by the charring.

If the Bourbon barrels are reused to make another whiskey those oils will be largely gone.

[Theophilus]

White Oak to be precise.