From Bruichladdich: "The effect of virgin oak on whisky can be dramatic. Head Distiller Adam Hannett must balance the immense sensory force of the raw wood whilst retaining the subtle complexity of the Octomore spirit. The solution demands a complex cask management system. Although all of the spirit in Octomore 08.4 is eight years old, just 20% has been held full-term in virgin oak. 80% was originally introduced to American oak, first-fill ex-Bourbon casks, before being transferred into the European virgin oak that had previously held Octomore 07.4." This whisky was peated to 170ppm of phenols.