Shortcut: Mizunara oak
Name: Mizunara Oak, known also as Japanese Oak, Latin name Quercus Mongolica.
Age: At least 200 years before it can be felled.
Appearance: As you might expect of a double centenarian: clearly very tough but is largely twisted and full of knots.
Sounds difficult to work with. It is. Expensive too. What’s more, the high water content makes it more porous than other oak varieties, which can make its casks prone to leaking…
Are we still talking about old people? What? No! You’ve taken that particular metaphor too far. We’re talking about Mizunara, the oak species native to Japan, name roughly translating to “water oak”.
Right. And how did this water oak get itself involved with whisky? It was first used on some scale during the Pacific War (1941-1945). During this time, Japan had no imports and whisky producers had to seek out a domestic alternative for their barrels.
Clever. What did they discover? Largely that it is a difficult wood to work with! The first time it’s used for maturation, Mizunara can impart a harsh, tannic quality to the spirit. It is for this reason that most blenders in Japan prefer to use refill Mizunara casks for maturation.
And those aforementioned leaks? Yes, for this, high water content and low tyloses levels are responsible.
Tyloses? Essentially a structure within wood that stops it from leaking. There are less of them found in Mizunara, meaning that it is a more porous oak than other varieties. Also, cutting across the grain of the wood for staves creates minuscule tubes leading from the inside to the outside making it easy for spirit to leak.
Does this seepage halt widespread use of Mizunara for whisky making? Yes. Scarcity is also an issue. The need to allow trees 200 years of growth before felling means Mizunara can command large prices at auction.
There is an auction for this stuff? Yes, and it is an extremely competitive affair! The limited amount of Mizunara oak that is available is primarily sold through a hard wood auction in Hokkaido, north Japan. The big boys at Suntory, Nikka et al must bid along with the cooperages and furniture makers.
I bet they have excellent taste. Speaking of which, what does Mizunara matured whisky taste like? Japanese oak can generate spicy and complex flavours. However, its typical aroma profile includes sandalwood, incense, vanilla and coconut.
Don’t say: Isn’t American oak a safer bet?
Do say: Porous another!