Fat Washing: What It Is, How to Do It, and Why We Use It in Our Cocktails

In the world of contemporary mixology, there is a technique that operates in the shadows of flavor: invisible to the eye, yet indelible on the palate. Fat washing —though we prefer to use its original name—allows bartenders to transform a conventional spirit into a completely new sensory experience. We’re not talking about a simple infusion or traditional maceration. We’re talking about a chemical-tactile process where fat becomes a vehicle for flavor and texture, leaving behind only its imprint: an enveloping silkiness that the customer perceives without being able to explain its origin. At Stillroom, we believe this technique represents the ultimate expression of our philosophy: The Art of the Invisible. The customer savors the complexity, but doesn’t see the 24 hours of work behind every drink.

What Is Fat Washing?

Fat washing is a mixology technique that involves infusing a spirit with an edible fat—such as butter, oil, or animal fat—to transfer aromatic compounds and flavor, and then separating the fat phase through freezing. The process takes advantage of fats’ ability to solubilize lipophilic molecules that alcohol cannot extract on its own: carotenoids, fat-soluble vitamins, phenolic compounds, and aroma molecules found in ingredients such as bacon, browned butter, or olive oil.

The magic lies in the temperature contrast. When the fat is heated alongside the distillate, the volatile compounds are released and dissolve into the fat phase. When we subsequently freeze the mixture, the fat—which has a higher melting point than water—solidifies into a layer that we can separate with surgical precision. The resulting liquid has absorbed the essence of the fat without retaining its visible oily texture. The customer gets a cocktail with body and depth, but without any perceptible oily residue. It is, quite literally, the art of the invisible applied to mixology.

How It's Done: The Step-by-Step Process

Fat washing is technically straightforward but requires precision and patience. Here is the complete process we follow at Stillroom:

• Step 1 – Choose the base spirit: The golden rule is to use a high-quality spirit that can withstand the transformation. Bourbon, vodka, white rum, or gin work particularly well. Avoid spirits that are too aromatic, as they may overpower the flavor of the fat.
• Step 2 – Choose the fat: The fat should be fresh and of premium quality. The most commonly used options are unsalted butter, toasted sesame oil, bacon fat, extra-virgin olive oil, cocoa butter, or coconut oil. The standard ratio is 30 ml of fat for every 750 ml of distilled spirit.
• Step 3 – Heat the fat: In a stainless steel bowl, heat the fat over medium-low heat until it has completely melted and reaches a temperature of about 50–60°C. Be careful not to overheat it to prevent it from burning.
• Step 4 – Mix with the distillate: Pour the distillate over the hot fat and stir vigorously for 2–3 minutes to create an unstable emulsion that facilitates the transfer of aromatic compounds.
• Step 5 – Resting: Close the container and let the mixture sit at room temperature for 4–6 hours. This allows the fatty compounds to fully blend with the alcohol.
• Step 6 – Freeze and strain: Place the mixture in the freezer for 12–24 hours. The fat will solidify into a visible layer on the surface. Carefully strain the mixture using a fine-mesh strainer lined with cheesecloth or a coffee filter to separate the solidified fat from the infused liquid.

The result is a spirit with aromatic complexity and a silky texture, ready to be used in signature cocktails. At Stillroom, we repeat this process up to three times with different fats to create increasingly sophisticated flavor profiles.

The Most Commonly Used Oils in Fat Washing

The choice of fat determines the final profile of the cocktail. Each one adds unique nuances that pair best with certain spirits:

• Brown butter: Perfect for bourbon and American whiskey. It adds notes of hazelnut and caramel, along with a subtle sweetness that rounds out the grain’s harsh edges. It’s our go-to choice for our signature Old Fashioned.
• Toasted sesame oil: Perfect for vodka and gin. It adds umami depth, toasted notes, and an oriental aroma that elevates citrus-based cocktails. Excellent in Martini variations.
• Bacon fat: A favorite among the most daring bartenders. It pairs exceptionally well with bourbon and rye whiskey, adding smoky and salty notes along with a meaty touch that defies cocktail conventions.
• Extra virgin olive oil: Especially the Arbequina variety. It adds herbal notes, vegetal undertones, and an incredibly silky texture. It transforms vodka into a cocktail with the body of olive oil, perfect for a reimagined Dirty Martini.
• Cocoa butter: The perfect companion for rum. It adds notes of chocolate and vanilla, along with a creamy touch that elevates the Daiquiri to the realm of a liquid dessert.
• Coconut oil: It works well with vodka and white rum. It adds a tropical sweetness, coconut notes, and a slightly thicker texture that’s noticeable on the palate.

Why It Works: The Science Behind the Technique

Fat washing isn’t magic: it’s chemistry applied to mixology. Fats are exceptional solvents for lipophilic aromatic compounds—molecules that don’t dissolve in water but do dissolve in fats. When we heat the fat along with the distillate, the aroma molecules are released from their original matrix and dissolve into the fat phase.

Alcohol acts as a catalyst in this extraction process, breaking down the cellular barriers of the ingredients and allowing the compounds to pass into the solution. The freezing process then takes advantage of a fundamental physical property: fat has a lower density than water and a higher melting point. As it solidifies, it forms a cohesive layer that we can easily separate.

The resulting distillate retains the aromatic compounds dissolved in the fat, but loses most of the fat itself. The result is a liquid that has absorbed the flavor complexity—toasty notes of sesame, the sweetness of butter, the smokiness of bacon—without retaining the noticeable fatty texture. It is precisely this paradox—the taste of fat without the fatty texture—that makes fat washing so fascinating.

Fat Washing at Stillroom: Our Philosophy

At Stillroom, fat washing isn’t just another technique—it’s a statement of principle. Enzo Ruiz, our Head Bartender and Creative Director, has developed a fat-washing program that represents the ultimate expression of our philosophy, The Art of the Invisible. Every spirit we infuse with fat undergoes a 24-hour process that the customer never sees, but experiences with every sip.

Our bourbon, infused with toasted hazelnut butter—a process repeated three times to achieve maximum complexity—serves as the foundation for a signature Old Fashioned that redefines this classic. The drinker experiences a creamy texture, notes of caramel, and a finish that no syrup or bitters can replicate. There are no traces of the process—just the flavor.

For our version of the Dirty Martini, we use vodka infused with Arbequina olive oil. The result is a cocktail that features the silky texture of olive oil—herbal notes, subtle bitterness, and a full-bodied mouthfeel—without any visible oily residue. It’s a Martini that has been kissed by olive oil but doesn’t show it.

And our cocktail menu wouldn’t be complete without a reimagined Daiquiri: white rum infused with pure cocoa butter, which adds notes of chocolate and vanilla and a creamy finish that transforms the experience. This Daiquiri exists in a space between a cocktail and a dessert, without being either.

Each of these cocktails represents hours of behind-the-scenes work. The customer doesn’t see the butter browning, doesn’t watch the mixture rest, doesn’t witness the freezing process. They simply taste the result. And that very invisibility is at the heart of our philosophy: excellence is demonstrated through what is felt, not what is explained.

Recipes to Try at Home

Although at Stillroom we take fat washing to a level that requires professional equipment, it’s possible to try this technique at home with satisfying results. Here’s an easy recipe for an Old Fashioned made with fat-washed bourbon:

Old Fashioned with Toasted Butter

For fat-washed bourbon (prepare 24 hours in advance):

• 750 ml of good-quality bourbon
• 30 ml unsalted butter

For the cocktail:

• 60 ml of fat-washed bourbon
• 10 ml of sugar syrup (1:1)
• 2 dashes of orange bitters
• Orange zest for garnish

Procedure:

First, prepare the bourbon: melt the butter over medium-low heat until it turns golden brown and smells like toasted nuts. Pour in the hot bourbon (you can let it cool slightly first), stir vigorously, and let it sit for 4–6 hours at room temperature. Freeze for 12 hours, remove the layer of solidified butter, and strain through cheesecloth. Done.

To make the cocktail, combine the infused bourbon with the syrup and bitters in a mixing glass filled with ice. Stir for 30 seconds and serve in a rocks glass with a large ice cube. Garnish with a twist of orange peel squeezed over the surface to release the essential oils.

The result: an Old Fashioned with a silky body, notes of toasted butter, and a finish that no traditional ingredient can match.

Come Discover the Invisible

Fat washing embodies everything we believe in at Stillroom: excellence isn’t seen—it’s experienced. Every cocktail on our menu hides hours of behind-the-scenes work and techniques that operate beneath the surface of flavor. We invite you to visit us at 9 Calle Moreto, in the heart of the Jerónimos neighborhood in Madrid. Come and discover what it truly means to taste the difference. The process is our secret; the pleasure is yours.

The History of Fat Washing: From PDT to Contemporary Mixology

In 2007, Don Lee, a bartender at Please Don’t Tell (PDT) in New York’s East Village, revolutionized mixology with a technique that would forever change the way we think about cocktails: fat washing. His most iconic creation, the Benton’s Old Fashioned, combined Four Roses bourbon with bacon fat from Benton’s, an artisanal Tennessee cure. He drew inspiration from the modernist salts David Arnold was experimenting with at Booker and Dax, applying culinary chemistry to the world of mixology.

The technique quickly spread to legendary venues like Empellón and Death & Co, reaching Madrid in the years that followed. Fat washing marked a turning point: wild mixology versus molecular cuisine, textures and flavors that once seemed impossible in a glass. At STILLROOM, we have integrated this technique as the foundation of our philosophy, “The Art of the Invisible,” where every element of the cocktail works silently to create memorable experiences.

Trends for 2026: Fat Washing in Spanish Signature Cocktails

The year 2026 marks the consolidation of “liquid umami” as a dominant trend in signature mixology. While bacon dominated bars a decade ago, today vegetable fats take center stage: avocado oil, cocoa butter, and pistachio paste are redefining the boundaries of flavor. In Spain, this evolution intersects with our rich charcuterie tradition, incorporating fats such as Colonnata lardo, Mallorcan sobrasada, and Iberian pancetta. Fat washing now coexists with lacto-fermentation and sous-vide in the most prestigious bars.

At STILLROOM, we’ve been exploring these techniques for years: toasted butter, sesame, pistachio, and Iberian pancetta are transformed into flavor infusers that add depth to the palate. To learn more about these methods, check out our section on advanced techniques and consult our mixology glossary.

Is it safe to drink a cocktail made using the fat-washing method?

Yes, it’s completely safe. The fat-washing process involves mixing fat with the distillate, gently heating it, and then cooling it. By separating the solid phase, impurities and most unwanted components are removed. The result is a liquid with a unique texture and flavor, but it poses no health risks. That said, it should always be prepared with high-quality ingredients and stored properly.

How long does a fat-washed spirit last before it goes bad?

A fat-washed spirit can last several weeks in the refrigerator, provided it is stored in an airtight container. Since it has been heated and then filtered, the risk of bacterial growth is significantly reduced. However, we recommend consuming it within the first 3–4 weeks to fully appreciate its aromatic nuances at their peak.

Can I do fat washing at home without professional equipment?

Absolutely. Homemade fat washing requires only a spirit (whiskey, rum, brandy), your chosen fat (butter, coconut oil, bacon), a glass bowl, a fine-mesh strainer, and patience. The basic process involves mixing, heating in a double boiler, cooling, and straining. With basic ingredients and the right proportions, any cocktail enthusiast can experiment in their own kitchen.

Which cocktails on the STILLROOM menu use fat washing?

On our current menu, you’ll find several drinks that use this technique. The Super Fashion (€16) is a brandy Old Fashioned with tamarind fat washing that balances sweetness and depth. The Green Margarita (€15) features cilantro fat washing for a vibrant, herbal experience. We also serve a house Old Fashioned with toasted butter, where the fat adds a unique creamy texture that envelops the bourbon.

Can you do fat washing with vegetable fats, or only with animal fats?

Fat washing works with virtually any type of fat, whether animal or plant-based. The most popular plant-based options include olive oil, avocado, coconut, cocoa, sesame, and pistachio. Each offers distinct flavor profiles: avocado oil provides a creamy subtlety, coconut adds tropical sweetness, and sesame brings a toasty, nutty note. The choice depends on the profile of the cocktail you want to create and the customer’s dietary preferences.

¿Quieres dominar la fat washing con tus propias manos?

El fat washing infunde sabores grasos en un destilado sin enturbiarlo: una de las técnicas más golosas de la coctelería moderna. En Stillroom Academy la enseñamos en directo, en nuestra barra de Moreto 9, dentro del curso Técnicas avanzadas de mixología.

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