In the crisp morning light of southern Ireland, we regard the sentinel oak that has stood anchored to this hillside near Stradbally, Co. Laois for the past 150-200 years. Season after season, her buds have burst into leaf, unfurled, and stretched up for the light, the broad canopy sheltering the forest floor far below. But she has seen her last summer.
Today, bright pink spray can markings signal the end for this swaying Irish giant. The buzzing of chainsaws breaks the morning stillness and in less than ten minutes, she is felled with a splintering crump. Don’t get too sentimental: she was chosen selectively and the coopering grade timber harvested here is destined to flavor new pot still Irish whiskey.
There is a historical precedent for using Irish oak to mature native whiskey although it has probably not been practiced since the 19th century. Sure, you may remember that Cooley produced Connemara Bog Oak whiskey a few years ago, but that was never likely to lead to an industry revolution. At Midleton distillery, master of maturation Kevin O’Gorman had been nurturing the idea of Irish oak maturation for many years. As Billy Leighton, their master blender, recalls from a conversation seven years ago, “One thing that sticks in my mind is that Kevin said, ‘I don’t want to do this, unless we do it right,’ which is the way we do things at Midleton.”
O’Gorman began to assemble the expertise he needed, beginning with Paddy Purser, consultant forester, to help identify a suitable supply of quality Irish oak and to ensure its sustainability. Tentatively, they undertook a series of maturation trials in small Irish oak casks made by Ger Buckley, their stalwart master cooper. Paddy explained the need to choose knot free, straight-growing trees, free from unsuitable spiral grains. His search for the best led them to Grinsell’s Wood on the Ballaghtobin Estate, Co. Kilkenny. Landowner Michael Gabbett owns a map drawn in 1820 that clearly shows an established wood in that location nearly two centuries ago. Today, there are about 200 mature oak trees in Grinsell’s Wood and they harvested just ten back in April 2012.
Ireland has relatively few remaining ancient forests. Currently, landowners are encouraged to apply for afforestation grants from the government to establish new woodlands. After witnessing the felling, Paddy takes us to see a stand of slender, silvery oaks in Ballykilcavan Forest, near Stradbally to explain what we might see growing in the cleared woodland in 20 years’ time. Trees are taken in groups of four or five to remove enough of the canopy to create enough light for regeneration to occur. The entire project is managed sustainably, meaning that the regeneration of the forest is actively managed to produce high-quality replacement oak trees in the future. For every tree taken out, there may be ten more oak trees planted. Clearly, there is never any intention to take more than the forest can regenerate.
Regeneration is a natural process, though there can be active planting to ensure the right species diversity. In 2010, these saplings in Ballykilcavan were thinned to take out competitors. Daubs of red and white paint encircle the trees that have the best potential to become quality oak for whiskey casks in a century or more. The lower branches are pruned so that when the tree’s crown develops, the growth is concentrated in the better quality stems.
Oak is a light-demanding species and needs light to grow. Holly and beech trees are shade-tolerant species that grow beneath the canopy of oak in the understory and middle story respectively. These shade the oak trunks, preventing the formation of unwanted epicormic branches that could result in knots that limit the value of the cooperage oak. Epicormics are produced if the crown is suppressed and the tree tries to produce a new crown, or if the tree is suddenly exposed to a lot of light and tries to take full advantage of the conditions.
Ballykilcavan Forest is managed close to nature, meaning they encourage a mixed forest with a diversity of species and tree ages, making it more resilient than a monoculture of oak. The mild, wet Irish climate provides a long growing season, with faster growth rates than the U.S. or Spain. This produces a hardwood that is a little less dense but more porous. A more open structure results in a greater oak contribution to the flavor of whiskey. O’Gorman and Leighton have found that Irish oak produces higher lignin breakdown products in the whiskey creating flavors of caramel, toffee, and vanilla.
So what’s the reason I’m squelching through the woodland in a hard hat with my homecoming Dubarry boots caked in mud? The new whiskey is called Midleton Dair Ghaelach: Grinsell’s Wood, the first in the Virgin Irish Oak Collection (I can help you with the pronunciation: try saying Der Gway-lack with conviction and you’ll sound like you know what you’re talking about). Attending the tree felling is the owner of the Maderbar sawmill in Barella in north-west Spain who will oversee the quarter sawing of the Stradbally trunks.
The foresters quickly calculate the volume of the fallen trunk by measuring its girth and length with tape measures (like the volume of a cylinder, they use πr2h). They determine that it should produce 4.4 tons of wood (the secondary wood has other commercial uses and the crown goes for firewood). The Co. Kilkenny trees from Grinsell’s Wood left Barella for the heat of Jerez, to be air seasoned over 15 months to get the moisture down under 16%. The Antonio Páez Lobato cooperage made 48 Irish oak hogsheads with a medium toast from those ten trees. Then they were repatriated to Ireland.
The virgin casks were filled with Midleton whiskies from 100% second and third-fill American oak barrels (typical casks of the Midleton style). These were mature batches of pot still, ranging from 15-22 years with a full range of styles from the lighter, more herbal end of the pot still character, through to the heavier styles that bring leathery and peppery notes. The casks were carefully watched and sampled over 10 months by Leighton and O’Gorman before bottling. Timing was critical to get the balance right.
With a tangential nod to the Buffalo Trace Single Oak Project, each bottle is marked with the tree number so that each whiskey can be traced back to a tree stump in the woods. Remarkably, we visited the stump of the tree that made the casks that finished the very whiskey we were drinking; something I’ve never experienced before. Each tree’s casks have been bottled separately, so there is some variation in strength from tree to tree (strength ranges from 58.1% to 58.5%).
Cooperage oak need not always come from Spain, France or the U.S. as whiskies from Glengoyne Scottish Oak to Hammer Head Czech whisky have proved. It’s a small step, but Irish Distillers believe there is no reason that Irish oak cannot play a greater role in the maturation of their whiskies in the future. As Kevin O’Gorman concluded, “It’s our barley, our water, our oak. It’s tasting history.”
Jonny’s full review of Midleton Dair Ghaelach will appear in the summer issue of Whisky Advocate.