This will be a short post, because while I found this fact to be a revelation, I suspect most people already know this intuitively, and to them, I sound pretty goddamn stupid.

It’s against policy to sound stupid in the public sphere, but I risk broadcasting my density here for the benefit of those who, like me, have always insisted on shaking the batches before every use.

Batching:

In a busy bar, you’ll often batch liqueurs, syrups, or even base spirits together to make service more efficient, turning a 5 pour drink into a 2 or 3 pour drink. Thus, for something like the Mane of Needles, say:
2oz Rye                                 — becomes —          2oz Rye
0.75oz Carpano Antica                                        1.75oz batch
0.5oz Campari                                                        dash orange bitters
0.25oz Benedictine
0.25oz Fernet
dash orange bitters

Easier, no? I’ve been a fan of batching for a long time, but I’ve always warned my bartenders: agitate the batches if it’s the first time you’re touching them that day. It only made sense to me that the constituent ingredients would settle out over time, the way juice does.

My intention was to figure how quickly they separated, not whether they did at all, so I set up a couple experiments. I made 5 cocktails with ingredients of dramatically different sugar levels, ABV, and colors (all that data is at the bottom. if you’re curious) sealed them in glass bottles, and tucked them away.

The general idea was to check every few hours to see how quickly the colors separated. My hypothesis was that it would happen within 6-8 hours.

First few hours: nothing. First few days: nothing. After two weeks, they still looked like this:

Convinced I was missing some minute but crucial gradient, I held it up to bright light and looked harder:

Zero color variation.

“Ok,” I thought, “maybe whatever accounts for color completely mixes in but something must settle out, right?” So I took a siphon, and siphoned off each bottle into three glasses: top 1/3rd, middle 1/3rd, bottom 1/3rd. And tasted them all side by side. And nothing. They’re exactly the same.

Do the ingredients really not separate over time?

Obvious Answer:

Of course they don’t separate over time.

If alcohol and water settled out, a bottle of vodka would be stronger on top than it is on the bottom. If sugar settled out of alcohol and water, a bottle of Campari would be sweeter on the bottom than on top.

When you first add things together, they’re not completely mixed, and you see sugary wisps in the liquid. But shake or stir it a couple times, and once those wisps go away — once it’s all fully mixed together — your job is done. The liquid doesn’t know it used to be 3 different things. All it knows is that is has a certain amount of water, sugar, and alcohol, and because of Brownian Motion, the levels thereof will be constant, throughout the liquid, until the end of time.

Again, this may be obvious to you. It may seem like I’m urgently tapping you on the shoulder to tell you that giraffes are tall. And in hindsight, yeah, of course. But it took me 2 weeks of experiments and a long text conversation with a friend who has a Ph.D. in chemistry (thanks, Addison) to work it out. So, you know. There’s that.

Bonus Fact:

Solids, of course, settle in the bottom of the bottle. In bottled citrus juice, the pulp starts to settle within the hour. But what about bitters?

Angostura bitters does indeed have tiny solid particulate matter that settles out over time. Look closely to the bottom of the bottle:

Clearer still is a brief close-up video to see them dancing about:

 

I couldn’t possibly tell you how much of an effect those little particles have on flavor. I have no idea. But it’s probably a good idea to not batch your bitters, and to add them à la minute to each drink.

Added Bonus Fact:

This principle has an appealing corollary, which is that if you, say, found an ideal gin and sweet vermouth for a Negroni, you could just pre-batch a bottle of negroni and keep it at home for easy cocktails after long shifts. Food for thought.

Experiment Data:

This wasn’t interesting enough to put in the body, but in case your curious, these are the cocktails I chose because the ingredients had widely disparate sugar & alcohol levels, and were of different colors. Sugar levels are taken from educated guesses by smarter people than myself, most notably Dave Arnold in Liquid Intelligence and this random, helpful little website.