What to Put in a Hip Flask Besides Whiskey
Any straight, high-proof spirit belongs in a hip flask. Rum, tequila, brandy, gin, mezcal and amaro all travel as well as whiskey does. What causes trouble is sugar, dairy or citrus – all three change while they sit. The 8 oz body on the Leatherius Personalized Leather Hip Flask is 316 stainless, which is the grade that copes best with a spirit sitting against it for days at a time.
What holds up, and for how long
| What you put in it | How it holds | Verdict |
|---|---|---|
| Bourbon, rye, scotch or Irish | Unchanged over days | The obvious answer |
| Rum, dark or aged | Unchanged over days | Excellent |
| Tequila and mezcal | Unchanged over days | Excellent |
| Brandy and cognac | Unchanged over days | Excellent, and the cold-weather pick |
| Gin | Botanical notes flatten slightly over a long sit | Fine for a day out |
| Amaro and bitter liqueurs | Sugar content means a proper rinse afterwards | Fine, clean it promptly |
| Cask strength whiskey | Unchanged, and it goes further | Arguably the best use of 8 oz |
| Wine | Oxidizes quickly once poured | Same day only |
| Pre-batched cocktails | Depends entirely on the ingredients | Same day, no citrus |
| Anything with citrus juice | Acidic, and it can pick up a metallic edge | Avoid |
| Cream liqueurs | Dairy spoils without refrigeration | Avoid |
| Sugary mixers and soda | Leaves residue, and carbonation builds pressure | Avoid |
The rule underneath the table
High-proof spirits are stable. Alcohol at 40% and above is inhospitable to almost everything, which is why a bottle of bourbon sits on a shelf for a decade and a carton of juice does not last a week. A flask filled with a straight spirit is closer to a small bottle than to a water bottle.
Everything on the avoid list breaks that condition. Citrus brings acid and cream brings dairy, while soda brings sugar along with pressure. None of these will destroy a 316 stainless flask in an afternoon. What they do is leave a residue you then have to clean out properly, and give you a drink that tastes worse than it did going in.
The other half of the answer is time. Nothing should live in a flask for a month, spirits included. That is a cleaning problem more than a chemistry one, and it is covered in How Long Can You Keep Whiskey in a Stainless Flask.
Coffee, tea and the non-alcoholic question
Cold brew coffee works for a day. It is dark and unsweetened, and it will not hurt anything, though it needs a thorough rinse afterwards because coffee oils cling. Hot tea is a bad idea in a flask of this kind – there is no insulation, so it will be lukewarm within the hour, and the cap gasket is not designed around heat.
For someone who does not drink, a flask still works as a gift. Non-alcoholic spirits behave like a cordial rather than like whiskey, which means sugar, which means clean it the same day. Cold brew is the better answer for a non-drinker who wants to carry something in a flask that gets used.
How much actually fits in 8 oz
Eight ounces is a little over five standard 1.5 oz pours, or eight generous one-ounce sips. In practice that is enough for two people over a long afternoon, or one person over a whole day without ever feeling short.
If you are filling flasks for a wedding party, a 750 ml bottle fills about three flasks with a splash left over. Eight flasks takes roughly two and a half bottles, or a 1.75 L handle plus a little more. Buy one extra bottle beyond your arithmetic, because someone always spills one. The shot-by-shot version of this math is in How Many Shots Are in an 8 oz Flask.
Cold weather and what to carry in it
Brandy is the traditional cold-weather fill and it earns the reputation, because the sweetness reads better at low temperature than a dry spirit does. Aged rum works the same way. A heavily peated scotch is the other direction and suits standing still in the wind.
Nothing you put in a flask stays warm. The steel takes the temperature around it, and the leather wrap is a comfort layer for your hand rather than insulation. Plan for the drink to be the temperature of the day.
What to fill a groomsman flask with
Fill it with what the groom drinks, and fill it on the morning rather than the night before. A wedding-day flask is a single toast for most of the party, so quality matters more than quantity – a bottle that would be extravagant for a night out is reasonable across eight flasks holding one round each.
Give the flasks empty when you hand them over, then fill them on the day. Rules for traveling with one are in Can You Bring a Hip Flask on a Plane?, and the ordering logistics for a whole party are in Matching Groomsmen Flasks With Different Initials.
Cleaning up after anything sweet
If you have carried amaro or a batched cocktail, rinse the flask with hot water the same day rather than the following week. Two or three rinses, then leave the cap off until it is dry inside. The full routine, including what to keep away from the leather, is in How to Clean and Care for a Leather-Wrapped Hip Flask.
Frequently asked questions
Can you put tequila in a stainless flask?
Yes. Tequila and mezcal both sit in 316 stainless as well as whiskey does, since a straight high-proof spirit is stable over days. Rinse the flask out afterwards as you would with anything else.
Is it safe to put citrus juice in a stainless flask?
Keep citrus out of a flask. It is acidic enough to pick up a metallic edge as it sits, and a margarita left in a flask overnight will taste noticeably worse than it did when you poured it.
How many ounces of whiskey fit in an 8 oz flask?
Eight, which works out at a little over five standard 1.5 oz pours. A 750 ml bottle fills about three flasks with a small amount left over.
Can you put hot tea in a hip flask?
You can, though there is little point. A flask of this kind has no insulation, so hot tea will be lukewarm within the hour, and the cap gasket is not built around repeated heat.
