Ask ten bartenders how to sweeten an old fashioned and you will get ten answers: a sugar cube, simple syrup, demerara syrup, muddled sugar, or a splash of something flavored. The reason the question comes up so often is that in a three-ingredient drink, the sweetener is not a detail. It is a third of the cocktail. This guide breaks down every common option, what each one does to the glass, and why a raw-cane syrup is the choice most serious home bartenders land on.
Why the Sweetener Decides the Drink
The old fashioned is whiskey, sweetener, and bitters, finished with a citrus peel. There is no mixer, no juice, nothing to hide behind. The whiskey brings the flavor and the proof. The bitters bring aromatics. The sweetener has three jobs at once: it tames the alcohol heat, it adds body and texture, and it shapes the finish. Get it wrong and even a great bourbon tastes thin or harsh. Get it right and a mid-shelf bottle tastes composed.
That is why "what sweetener" is the most important question in the drink, and why it is worth taking seriously.
The Common Options, Ranked by What They Actually Do
Sugar Cube (the traditional method)
The original build muddles a sugar cube with bitters. It is romantic and it works, but it is inconsistent: the sugar never fully dissolves, so you get grit at the bottom and uneven sweetness from sip to sip. Fine for tradition, frustrating for a reliably good drink.
Standard Simple Syrup (1:1)
Equal parts white sugar and water. It dissolves instantly and sweetens evenly, which solves the grit problem. But 1:1 syrup is thin, it adds noticeable dilution, and it brings sweetness and nothing else. The drink ends up watery at the finish.
Rich / Demerara Syrup (2:1)
Double the sugar, and use demerara or raw sugar for more flavor. This is a real step up: less dilution, more body, and a faint molasses warmth from the demerara. Most cocktail bars use some version of this. The downside is you are still making and storing syrup that spoils in a few weeks, and the flavor is a byproduct rather than the point.
Flavored Liqueurs
Some people reach for maple liqueur or an orange liqueur to sweeten and flavor at once. The problem is you are also adding more alcohol and often a lot of artificial sweetness, which throws off the careful balance of the drink.
A Raw-Cane Cocktail Syrup
This is where Proof Syrup Traditional comes in. It is made in small batches from raw cane sugar, so it has the body and warmth of a demerara syrup with a cleaner, rounder finish, and it pours and measures exactly like simple syrup. You get the richness serious bars chase without the guesswork, and it is built to last on your shelf rather than spoiling in a fortnight.
Why Raw-Cane Syrup Wins for an Old Fashioned
Proof Syrup was built for exactly this slot. Because it is made from raw cane sugar rather than refined white sugar and water, it brings genuine depth: it rounds the whiskey's edges, softens the heat, and gives the drink a finish that lingers instead of dropping off. Where 1:1 simple syrup thins out at the end of the sip, a raw-cane syrup holds. That is the single biggest quality difference most people can make in their old fashioned, and it takes zero extra technique, you just pour it where you used to pour simple syrup.
The other advantage is range. Once the sweetener can also carry flavor, it becomes a lever for the whole drink.
Matching the Syrup to the Old Fashioned You Want
Here is how the live Proof Syrup flavors map onto the drink:
- Classic and clean: Traditional โ pure raw-cane richness, lets the whiskey lead.
- Brighter and citrus-forward: Orange โ deepens the orange peel, more approachable.
- Nutty and warm: Pecan โ a Southern, dessert-leaning take.
- Earthy and sophisticated: Black Walnut โ the most grown-up, spirit-forward version.
- Smoky and savory-sweet: Maple Bacon โ a cozy fall twist that converts skeptics.
If you cannot decide, that is exactly what the Old Fashioned Mini Set is for: it puts the core flavors together so you can build a different old fashioned every night and find your house version.
The Simple Build, Whatever Syrup You Choose
Ingredients:
- 2 oz bourbon or rye
- 1/4 to 1/2 oz Proof Syrup (Traditional or a flavor)
- 2 to 3 dashes aromatic bitters
- Garnish: expressed orange peel
Instructions: Stir all ingredients over ice for 30 to 40 seconds, strain over one large cube, express the orange peel over the top, and serve. Start with 1/4 oz of syrup and adjust to taste.
The Bottom Line
You can make a fine old fashioned with a sugar cube and a lot of patience, or a good one with simple syrup. But the easiest upgrade available to any home bartender is to fix the sweetener slot with a raw-cane syrup that brings real body and flavor. It is the one change that makes the biggest difference for the least effort.
Start with Proof Syrup Traditional, or grab the Old Fashioned Mini Set to find your favorite. Browse the full lineup of Proof Syrup flavors to build your bar.
