Is it possible no one ever taught you to split milk? That’s about to change. In this post we’re going to teach you the art of dividing up a pitcher full of steamed milk in such a way that you end up with the same amount of foam in each beverage you pour. And judging by what we saw after visiting a great many highly rated cafés across Europe on our recent trip to World of Coffee, this practice is very much a lost art in the specialty coffee scene. Don’t think technology will spare you the trouble of learning this skill in the foreseeable future. Based on our observations in Switzerland and the UK, it’s very much not the norm for cafés to be using autofoamers like La Marzocco’s Wally Milk or an Ubermilk. That’s because, whilst being quite brilliant technology, they cost almost as much as an espresso machine (+AUD10K) and, it should be said, thanks to the ‘latent heat of condensation’, the steam wand is pretty damn efficient at heating milk. 

I’ve got a pretty good theory on why milk splitting is so seldom seen in cafés now. In 2016, the World Barista Championship made some dramatic changes to the rules and made technical judges into little more than hygiene monitors. They removed almost all the attention they once placed on technical and replaced it with a very strong emphasis on flavour. That’s very nice, but baristas in the WBC were once exemplars of best practice in café service. However, that is certainly no longer the case. If you look at the rules and regs for the WBC now, the solitary technical judge (there used to be two) checks very carefully if the steam wand is wiped and purged, and between them, the sensory and technical judges do practically nothing else to evaluate the technical skill of the barista, apart from checking if they spill a bit of coffee. (If you happen to be looking for a means of testing your technical skill as a barista, try this.)

Sensory judges used to evaluate foam depth by pushing the back of a teaspoon through the foam, which sure looks quaint these days, and if there was less than 10 mm of foam, they’d each dock you a point on their sensory score sheet. The thing is, whilst sensory judges are now trained to focus on “harmonious balance of the sweetness of the milk and its espresso base”, to quote the rules and regs from the WBC, do you know who actually still pushes a spoon through their milk beverage? Virtually every customer you provide with a cup and spoon, i.e., all your dine-in customers. Of course, if you whack a lid on a take-away cup, the excess of foam or an absolute dearth of it may escape notice, but any dine-in customer will notice and care if you have got inconsistencies in the way you foam your milk. If you sell a customer a blueberry muffin one day and it has a dozen blueberries in it — and then the next day, they come back and order a muffin with only two… they’re going to notice, right? It’s the same with foam. Absolutely no one likes spilling an under textured milk-based beverage all over their saucer.

And what if you have two customers who order two lattes in glasses? If you don’t split the milk and you just pour the top half of the milk pitcher into the first latte and the bottom of the milk into the second latte, they’re gonna come out looking like this:

Here’s how to get them both looking and tasting the same. This is how we teach you to split your milk in our flagship course Barista One.

This method requires two milk pitchers: a larger one for steaming and a smaller one for pouring. Follow this protocol every time you’re making two drinks at a time:

1: Mentally divide the milk into four separate sections.

2: Pour three-quarters of your freshly steamed milk into the smaller pitcher. This will pour out most of the air bubbles into the smaller pitcher, leaving the least foamy quarter behind in the larger pitcher.

3: Return one of those quarters back to the larger pitcher. This has the effect of returning the foamiest quarter to the larger pitcher.

After pouring your lattes, the foam will be equally divided like this.

Your Latte Art Needs You to Split, Too

If you are into latte art and you’ve been noticing some inconsistencies, then milk splitting will dramatically improve your latte art, too. If you try to pour a pattern with milk that is drawn from the top of a pitcher, i.e., parts 1 and 2 from the diagram, then you will notice you are really limited in the designs you can pour because almost certainly your milk will be too foamy. The most you can hope for is a heart or a very rudimentary tulip with very few petals. 

Similarly, if you pour a pattern with parts 3 and 4, the milk will be really thin and under-aerated. Drainage will take place much more quickly and your designs will slip across the surface of the milk and each component of your design will look thin.

What’s Drainage?

When the bubbles in a freshly poured latte appear to be falling down instead of floating up, what you are actually seeing is liquid draining out of the bubbles. This is due to the process of drainage. If you’ve ever ordered a pint of Guinness or a stout beer, you will have seen very well what drainage looks like. 

From a taster’s sensory perspective, slow draining can be very pleasant, imparting a velvety texture. From a practical, latte art perspective, the 10-second rule is something to aim for, that is, begin pouring in no longer than 10 seconds after steaming is finished. Otherwise, the drainage of your foam will have advanced too far and your milk will separate into a liquid layer and a dry foam layer.

And when you’re doing two drinks at a time — which you should in a café where possible, because it’s so much faster than steaming individually — then you need to begin splitting your milk within ten seconds of steaming, before too much drainage has taken place.

Counteracting Drainage

Foams can be stiff, runny, or some form in-between. In physics terminology, these qualities are called either ‘elasticity’ or ‘plasticity’. What changes along this continuum from stiff to runny is the amount of elastic and plastic strain. After a material reaches its yield point, it no longer just flexes; it elongates (plastically) and begins to be permanently deformed. The level of stress needed to trigger this change is the yield stress. For good latte foams, we want a low yield stress.

Around 60 seconds after steaming has finished, the yield stress of the milk increases via the process of drainage. The more that time passes and drainage occurs, the closer your foam gets to being unusably ‘elastic’. You have seen baristas spinning milk jugs to create a whirlpool before they pour. This process is not strictly necessary if you steam and pour immediately, but if there is a delay in your workflow, such spinning can help to restore milk back into a usable condition. If, perhaps, you steamed enough milk for two drinks, and the milk for the second drink has been set aside for some time, then it is necessary to undo the drainage process. Spinning your milk jug around or transferring your milk into a new jug will restore the liquid around the bubbles and will take your foam further from the yield point, to ensure your bubbles can slide past each other again. The term in surfactant science for how readily bubbles can slide past each other is their sliding friction.

If you want to follow up on your milk science, or advance your knowledge of latte art further, then check out for these two online courses and certifications — Milk Science, and Latte Art, both included in our monthly BH Education subscription.