Killowen Distillery: Mixed Mash Bills, Wild Fermentation, and Irish Whiskey That Remembers What It Is

This episode has been a long time coming.

I was first introduced to Brendan Carty through Alan Bishop, back when Alan may still have been at Spirits of French Lick, and Killowen quickly became one of those distilleries I knew I had to get on the podcast. Part of that was the liquid, of course. Part was the history. Most of it was Brendan’s willingness to challenge almost every neat, simplified story the modern Irish whiskey industry likes to tell about itself.

Killowen Distillery sits high in the Mourne Mountains of County Down, overlooking the Irish Sea and producing whiskey on a scale closer to an old farm distillery than a modern visitor-center cathedral. Direct-fired stills. Worm condensers. Boat paddles in the mash tun. Mixed grain mash bills measured in sacks rather than decimal points. Open fermentations exposed to the yeasts and bacteria living in the hedgerows and mountain air.

It would be easy to describe Killowen as backward-looking, but that misses the point. Brendan is deeply interested in history without wanting to embalm it. The aim is not to recreate a dead mash bill and congratulate himself for accuracy. It is to understand what made Irish whiskey extraordinary, restore the parts that were lost, and then let Killowen become its own thing.

From Architecture to a Different Kind of Construction

Before Killowen, Brendan was an architect.

That career had taken years of study, a large amount of debt, and no small amount of commitment. Walking away from it was not a whimsical leap toward a romantic life among copper stills. It was difficult, expensive, and at times brutal.

The idea had been building for years. Brendan already loved whiskey and understood its place within Irish culinary history, but he also felt the story was being told badly. Modern Irish whiskey had become dominated by large companies, simplified narratives, and a narrow definition of what Irish pot still whiskey was allowed to be.

At the same time, other voices were beginning to cut through. Fionnan O’Connor’s research, particularly A Glass Apart, helped document the mixed mash bill tradition that once defined Irish whiskey. Trips to Tasmania introduced Brendan to Peter Bignell at Belgrove, where direct fire, unusual grain, practical engineering, and place-driven distilling showed what could happen when someone ignored the accepted template.

The answer, naturally, was to abandon a stable profession and build an extremely small distillery in the mountains.

Someone had to do it.

The Killowen Doctrine

Killowen began production in 2019, but the core philosophy was established from the first day.

Brendan calls it the Killowen Doctrine. It is a physical document, now well worn, signed by everyone who has worked at the distillery. It lays out the center of gravity: protect and revive genuine Irish pot still whiskey, work sustainably, reflect the local community and region, and remember that the goal is not simply to reproduce the past.

The doctrine gives the team something firmer than a product roadmap. The portfolio has expanded beyond what appeared in the earliest plan. Killowen has released bonded whiskey, poitín, gin, liqueurs, sourced and blended projects, and tiny experimental runs alongside its own maturing spirit.

Those products help keep the business alive and create room to explore, but the central purpose has not shifted. Killowen still exists to help repair Irish whiskey’s connection to its own history.

That repair work begins with the Irish whiskey technical file.

The Irish Whiskey GI and the Mash Bills It Left Behind

Modern Irish whiskey regulations recognize pot still whiskey as a mixture of malted and unmalted barley distilled in pot stills. They also allow oats, rye, and wheat, but cap those grains at levels Brendan and many other researchers believe bear little resemblance to the category’s historical reality.

That matters because oats, rye, and wheat were not decorative flourishes in old Irish mash bills. They could make up a substantial portion of the recipe and were central to the flavor and identity of Irish pot still whiskey.

The compromise currently under discussion is often described as a 30-30-30 approach: minimum levels for malted and unmalted barley, with up to 30% of oats, rye, and wheat. It may not capture every historical mash bill, but it would make far more room for the category’s actual heritage than the current limit.

Brendan’s interest is especially focused on those adjunct grains. Unmalted barley matters, but oats, rye, and wheat bring energy, texture, flavor, and variation. Without them, pot still whiskey risks becoming a narrowly regulated version of itself, legally protected from much of its own history.

Killowen therefore makes both GI-compliant and non-GI-compliant spirit. The compliant version can legally become single pot still Irish whiskey. The others may be historically recognizable as pot still whiskey, but the current rules do not allow the name.

That contradiction sits at the center of Killowen’s work.

Mixed Mash Bills Measured in Sacks

Killowen’s mash bills are described in sacks and half-sacks rather than tidy percentages.

There is something charming about that, but it is not just presentation. The mash tun holds a fixed number of bags, and the recipes are built around the physical work of emptying them into the tun. It keeps the process on a human scale.

Percentages matter to regulators. Bags matter to the people stirring the mash.

Killowen works with several core recipes, including a GI-compliant mash bill and evolving non-compliant mixed mash bills. Poitín recipes change more freely depending on the release, and experiments can involve anything from heavy oat content to rye and heritage barley.

The grain itself is only part of the challenge. Someone still has to move it around the mash tun, usually with a boat paddle.

That becomes particularly memorable with rye.

The Paddle Breaker

Killowen once attempted what began as a 100% rye mash. The rye drank water, clumped together, turned into glue, and began consuming paddles like a small wooden predator.

Barley was eventually added to loosen the mash, bringing the final recipe closer to 90% rye. The finished release was appropriately named Paddle Breaker.

Brendan finds oats far easier to work with, which may surprise American distillers who have sworn blood oaths against them. Part of the difference is the grain itself. Local oats retain their husks, which help keep the mash buoyant and create channels for liquid to move through. Remove the husks and the oats become a far more miserable proposition.

Rye, meanwhile, remains rye. Delicious, expressive, and occasionally capable of turning the mash tun into masonry adhesive.

Oats, Texture, and Custard in the Glass

Oats have a special place at Killowen.

Their value goes beyond texture, though they bring plenty of that. Brendan compares them to fat in cooking, an ingredient that carries flavor and gives the whiskey body. When malted, they can produce deep creamy and custard-like notes that differ from the yogurt, fruit, and cereal character of malted barley.

They are also difficult to malt.

The grain is wrapped in a thick husk, making it harder to see how germination is progressing. Oats hold moisture and take longer to dry, increasing the risk of mold. Kilning requires enough heat to reach the kernel, sometimes to the point that portions begin to toast or caramelize.

That difficulty is exactly why large-scale production tends to move away from grains like oats. Lower yield, more labor, more energy, and less alcohol per ton are terrible arguments on a spreadsheet.

They can be excellent arguments in a glass.

Killowen has also peated oats, finding that their oils hold smoke particularly well. The resulting spirit combines creamy weight, custard-like malt character, and turf smoke in a way malted barley alone cannot reproduce.

Whiskey Made by People and Place

Killowen sits within the Mourne Gullion Strangford UNESCO Global Geopark, high in the mountains and exposed to the Irish Sea.

The location is beautiful. It is also inconvenient.

Large lorries cannot reach the distillery, so deliveries may have to be met lower down the mountain. Drivers who ignore instructions can find themselves stuck for hours, occasionally leaving pieces of walls or vehicles behind. Local farmers and trusted delivery partners help bridge the gap.

That difficulty is not incidental to Killowen’s identity. The distillery exists where it does because Brendan believes whiskey should come from people and place.

He is cautious with the word terroir. Grain is not a century-old grapevine, and whiskey does not emerge untouched from a field. The farmer, maltster, distiller, fermenter, still, cask, warehouse, and community all intervene.

“Sense of place” leaves room for those people.

Killowen’s place includes the mountain weather, the Irish Sea, tiny surrounding farms, local animals eating the draff, hedgerows carrying yeast and bacteria, and a distillery compact enough that every batch still passes directly through someone’s hands.

Open Fermentation and the Mountain in the Wash

Killowen ferments in open-topped IBC containers, allowing the local environment to participate.

The wort can spend time exposed before cultured yeast is added. Wild bacteria and native yeasts enter from the air, hedgerows, fruit, animals, and the broader mountain environment. The microbial balance changes with the seasons. Autumn decomposition brings different activity from winter cold or summer warmth.

This is not an accidental infection that Killowen tolerates. It is part of the process.

The bacteria can lower the pH and prevent the cultured yeast from consuming every available sugar. That reduces yield and sends residual sugars into the still, exactly the sort of inefficiency a large distillery would normally eliminate.

Those sugars then meet direct flame.

Killowen has run cleaner, more controlled fermentations and achieved better yields. The resulting spirit was less interesting. The numbers improved while the whiskey lost part of its voice.

That is an easy decision when flavor is the governing metric, although accountants may experience a small twitch.

Direct Fire and the Flavor of Hot Spots

Killowen uses direct-fired stills, a method Brendan considered non-negotiable from the beginning.

Steam and electric heat can be efficient and controllable, but they produce a more even heat. Direct flame creates hot spots at the base of the still, encouraging Maillard reactions and caramelization as proteins and sugars cook against the copper.

Brendan compares the difference to boiling a steak versus searing it in a pan. Both methods apply heat. Only one creates the crust.

The effect is not subtle to him. Direct-fired spirit carries a burnt, savory, cooked dimension that can be as significant as the distinction between peated and unpeated whiskey.

The stills require more work. The bases need cleaning, though Brendan does not want to polish away every trace of use. A seasoned still is closer to a cast-iron pan or barbecue than a piece of laboratory glassware. Clean enough to function, dirty enough to remember what it does.

The fire has also become more efficient over time. Jackets around the stills retain heat and shorten winter distilling days that could otherwise stretch well beyond 12 hours. The technology is accepted because it makes the process more practical without removing the flavor Killowen is built around.

The same logic applies to the forklift. History is important. Hernias are optional.

Worm Condensers and Whiskey That Takes Its Time

Killowen also uses large worm condensers, making it unusual even among small Irish distilleries.

The vapor travels through serpentine copper coils submerged in cooling water, condensing slowly. That pace extends the distillation and gives the spirit more time in contact with copper and heat.

The worms are not efficient. That is the attraction.

Longer distillation means more time over direct flame, more development at the base of the still, and a heavier, more textural spirit. Brendan is not pursuing “smoothness,” a word he considers closer to an insult than a compliment.

He wants complexity and balance. A whiskey that tastes of what happened to it.

Cuts by Nose, Taste, and a Little Boot Rubber

Killowen’s spirit changes from batch to batch because the grain, fermentation, weather, and microbial environment change. Fixed cut points would impose a false consistency over a living process.

Cuts are therefore made by nose and taste, with formal measurements taken as required for HMRC.

Brendan does not want the cleanest possible heart cut. A touch of acetone, rubber boot, heavier oils, and transitional character can make the final whiskey more compelling. Remove every rough edge and you may also remove the pieces that grow into complexity during maturation.

That approach requires attention. It is also one of the reasons Killowen cannot be reduced to a recipe card.

The distillery shares mash bills and process information openly because no one can truly duplicate it. The equipment, wild fermentation, people, location, sensory cuts, and accumulation of tiny decisions are part of the recipe too.

Triple Distillation and the Three Great Irish Whiskey Myths

Irish whiskey is frequently summarized through a handful of phrases: triple distilled, unpeated, and smooth.

Brendan pushes back against all three.

Irish whiskey was not historically all triple distilled. It was not universally unpeated. Pot still whiskey was not one rigid recipe. Those ideas became useful marketing shortcuts and were eventually repeated until they sounded like ancient truths.

Triple distillation can make excellent whiskey, but it also requires more energy and can remove flavor. Killowen’s goal is not maximum purity. It is character.

The distillery draws from both Irish and global tradition, including the thumper concept Brendan encountered through American and Caribbean distilling. It is an appropriately circular exchange. Irish mixed mash bill culture influenced American whiskey, survived more strongly there, and is now returning home with a few American tools in its luggage.

Peat, Turf, and the Missing Kiln

Killowen’s early spirit included peated and turf-smoked grain, some of it sourced from Donegal and some from the Mourne Mountains.

The different turf sources brought different profiles. Donegal could lean sootier, while local turf carried a more familiar earthy smoke. Killowen built a small smoking and malting setup to work directly with barley and oats, integrating smoke before distillation rather than treating it as a purchased specification.

Then the peating shed burned down.

The irony is almost too neat, but the loss was real. Rebuilding remains on the priority list, though difficult market conditions mean other projects have to come first. As a result, the whiskey made over the past few years has been predominantly unpeated.

That may delight some drinkers, but the goal is to return to smoking and peating grain. The work was too central to Killowen’s ideas about historical Irish whiskey, regional flavor, and the difference between simply buying peated malt and making it yourself.

Poitín as Ireland’s Living Spirit

Poitín is not a side category for Killowen. It is part of the foundation.

Often described abroad as Irish moonshine, poitín survived centuries of prohibition after being driven underground largely through excise policy. It was made regionally, often with oats, barley, mixed grains, and smoke. It carried local variation because it was produced by communities rather than standardized corporations.

That is exactly what makes it important now.

Brendan sees poitín as Ireland’s answer to mezcal, a category that should express regions, producers, grains, methods, and traditions rather than collapse into neutral spirit with an Irish label. He believes the rules need to protect it before larger companies strip away the character that makes it worth preserving.

Killowen’s poitín recipes can change, reflecting the freedom of the category. Some are lightly aged, some peated, some built around mixed grain, and some tied to collaborative projects such as those connected with Fionnan O’Connor’s research.

Poitín does not necessarily make Killowen much money. It does something more important.

It keeps the older language of Irish distilling alive.

Bonded Whiskey, Transparency, and Keeping the Lights On

Killowen’s own mature stock is tiny, and building a distillery around small-batch spirit requires financial creativity.

Bonded and sourced whiskey gave the company a way to reach drinkers while its own spirit matured. Releases have included blends, finishes, single malts, poitín, and projects built from liquid sourced from other Irish distilleries.

Brendan has pushed for transparency in those releases, at times drawing complaints from people who seemed more upset by honest labeling than by vague industry practices. The intention is not to confuse consumers. It is to tell them what is actually in the bottle.

That willingness to use sourced whiskey does not weaken Killowen’s identity. The blending, finishing, cask selection, and product ideas still express the people behind the distillery.

More importantly, those releases funded the slower work: direct-fired spirit, mixed mash bills, wild fermentation, turf-smoked oats, and tiny volumes of whiskey that could never support the company alone at the beginning.

KD 186 and the Arrival of Killowen Whiskey

Killowen’s own mature whiskey is finally beginning to emerge.

I tasted KD 186, a traditional mixed mash bill distilled in November 2022 and matured in a full, proper oloroso sherry cask. At a little over three years old, the color alone suggested a whiskey with something to say, and the palate delivered.

The cask brought depth without erasing the spirit. Leather, cigar leaf, dark fruit, and sherry character sat over a whiskey that still carried the texture and mixed-grain identity Brendan has spent years trying to protect.

The release sold out quickly, which means there is little point hunting that exact bottle now. What matters is what it represents.

Killowen is no longer only a promise, a poitín producer, a bonded whiskey house, or a campaign for better Irish whiskey rules. The distillery’s own whiskey is here, and it tastes like the ideas behind it were worth the trouble.

Small by Design

Killowen has never been built around the idea of becoming enormous.

The physical site would fight that ambition even if Brendan wanted it. The distillery is compact, the road is difficult, the stills are small, and production is measured in tiny runs rather than tanker loads.

If Killowen expands, Brendan has often imagined another small distillery elsewhere rather than turning the existing site into something industrial. Growth through breadth, not bloat.

That idea aligns with his belief in regionalism. A second distillery should belong to its own place rather than becoming a larger clone of Killowen. The model is less a factory network and more a family of individual voices.

In an industry where success is often measured by how quickly a distillery can erase its original scale, choosing to remain close to the process feels almost radical.

The Culture Inside the Whiskey

Toward the end of the conversation, we moved away from equipment and mash bills and toward something more personal.

Brendan has spoken about Ireland needing greater pride in its language, mythology, regional culture, and culinary traditions. Whiskey is part of that larger cultural inheritance.

He did not necessarily imagine when he was younger that he would become one of its ambassadors. Yet Killowen now gives him that opportunity.

The distillery represents the Mournes, County Down, Northern Ireland, the border region, and the wider island without reducing any of those identities into a tidy tourism slogan. Ireland is intensely regional. Killowen’s whiskey should not taste like a generic national product with a mountain printed on the label.

It should carry the people who made it, the place where it fermented, the grains that fought the paddles, the fire that cooked it, the worm that slowed it, and the history that refuses to stay neatly in the past.

What Killowen Is Trying to Restore

Killowen’s story can be framed as a revival of old Irish whiskey, but “revival” only gets part of it.

Brendan is not recreating a museum recipe. He is restoring permission.

Permission for Irish pot still whiskey to use meaningful amounts of oats, rye, and wheat. Permission for spirit to be smoky, oily, dirty, seasonal, and regionally distinct. Permission for poitín to be treated as a serious cultural spirit. Permission for small distilleries to build something different from the multinational model.

The machinery matters. The GI matters. The grain matters. The research matters.

But the larger argument is simpler.

Whiskey becomes extraordinary when people and place are allowed to remain inside it.

Killowen Distillery