As the Irish whiskey category comes into its own, makers are ramping up the flavour by including an ever-greater number of cask types in single expressions. Is this a case of successful differentiation, or does the practice risk becoming faddy, asks Kristiane Sherry.

Much has been written about the rise and rise of Irish whiskey. In just a decade, the industry has blossomed from four to over 40 distilleries. The category might have hit a bit of a road bump in 2023 (according to trade association Bord Bia, exports slipped 14% to €875 million) but makers remain unperturbed. While the headwinds stormed in from Irish whiskey’s biggest market, the US, sales to the EU soared by 17%, and the UK saw 38% growth. Momentum remains very much with the category.

Key historical and legislative differences have long set Irish whiskey apart stylistically from other producing nations. The vast array of permissible cask types tops this list. Scottish producers have to use oak, and prior contents must adhere to a strict specification. Broadly, “traditional” drinks are allowed, or beer, ale, wine or spirit where there has been no added sweeteners. And absolutely no stone fruits. Irish distillers, on the other hand, can play with all manner of woods, and prior contents must simply be “other alcoholic beverages”. It’s a veritable playground of flavour – and makers are upping their collective game.

Some argue that the influence of the cask is even greater for Irish whiskey, due to the widespread use of triple distillation. “It’s even more important to have the very best casks and very best flavours,” reckons Dave McCabe, master blender at Irish Distillers. “It’s a subjective view, but we agree with this.” Is it any surprise then that almost every recent launch of Irish whiskey has been made with three, four or, five types of cask? The question really is how much is too much? Have distillers already gone too far, and is there a risk that consumers will get confused? Or worse – that quality will fall and the category will suffer?

Alex Chasko is master distiller at Dublin distiller Teeling (pictured top right). Its single malt makes use of five different casks: new American oak, ruby port, Carcavelos white port, Madeira and bourbon. More widely, he says he has used more than 200 varieties. “These include the likes of wine, beer, rum, and aquavit through our Small Batch Collaboration Series, as well as other wood species like virgin American oak, acacia and amburana, to name but a few.”

And one of the biggest names in Irish whiskey is in on the act, too. Jameson Single Pot Still makes use of five cask types: American bourbon, oloroso sherry and three typs of new oak – American, Irish, and European. “We also have our unique microdistillery which focuses on experimenting with casks, via the Method & Madness brand,” adds Kevin O’Gorman, master distiller at Midleton. “We are always working in the background, experimenting with different wood types – chestnut, acacia, cherry, hickory.”

But as Rocío Trillo Ollero, master distiller of brandy and spirits at González Byass, maker of Nomad single malt whisky, notes, not all casks are created equal. (The Nomad concept was borne out of the use of sherry casks, and the company has just launched the Irish version.) It’s all well and good playing the volume game, but if the cask-spirit partnership isn’t compatible, or the cask simply isn’t good enough, the whiskey could be ruined. “The main goal should always be to maintain balance and ensure the quality of the final product to achieve a successful whisky.”


Of course, not everyone is using a plethora of casks to shout loudly. Waterford, known for its biodynamic approach to distilling, uses four casks across all its whiskeys – first-fill American oak, new American oak, premium French oak and vin doux naturel – but they never overpower. “Our approach to oak is based on a desire for barley to be the primary driver of natural flavour in our whiskeys,” explains head distiller Ned Gahan.

“Although oak is the most expensive element of our production costs, it is a minimal aspect of how we present Waterford whisky.” Whiskeys will never be released under a “four wood” label, he says. “Importantly, all is full-term maturation, no finishes. Our feeling is that there’s no need to finish if one has started well.”

Another producer taking a fundamentally different approach is Roe & Co. The Diageo-owned producer released its inaugural whiskey back in February. Solera Single Malt First Edition uses five types (refill and first fill American oak ex-bourbon, new alligator charred American oak, and chestnut barrels with two custom toasting profiles), which all sit in a solera system, with each criadera dedicated to a different style.

“It centres people and process, and the instinctive parts of whiskey making,” says head distiller Lora Hemy. “It might involve sampling casks and tasting of increments over time then putting something together as a recipe in a lab and enacting it. This has been more of a live whisky creation process.”

She says she’s never worked in this way before, which is more akin to layering flavour over time rather than anything like finishing. “We’re actually thinking about it as a sort of early stage version of blending whiskey.” As a result it feels like the polar opposite of a fad.

For Slane Irish whiskey, which focuses on triple casking, it’s important not to take quirky cask maturations too far. “Just because it’s unusual doesn’t mean that it tastes good,” Gearóid Cahill, master distiller and distillery manager, says. “While the quest continues for rare or unusual casks for maturation or finishing, distillers and blenders must remember that delivering a whiskey with a fantastic taste is the ultimate goal.

“The marketing of a whiskey based on its unusual cask type will not get you too far if the whiskey flavour is not there.”

Alex Thomas, master blender at Bushmills and no stranger to using myriad casks, likens it to cooking. “Would you say the same thing to a chef? How many flavours can you put together to make a meal?” She says the approaches of Michelin-starred chefs and whisky makers are not all that different. “It’s more about the balance and the complexity and not just pushing it for the sake of pushing it.”


While there is a common feeling that cask experimentation in Irish whiskey isn’t going anywhere, most producers agreed that a renewed focus on toasting and charring is due – processes that influence flavour and that could never be seen as a fad. And there needs to be a move to re-centre the end drinker to keep it relevant.

“I feel the consumer will dictate the conversation as they have always been looking for new expressions,” predicts Teeling’s Chasko. “As producers our job is to have a wide range of options and to be in contact with people enough to identify trends as they become apparent.”

And if that leads to something of a fall-out in terms of myriad casks, so be it.

(Image: Teeling street art)