I’d like to humbly begin by tipping my hat to a man that fueled my coffee obsession half a decade ago, when I had either fatefully or coincidentally stumbled into the world of coffee and found myself in a city that was starved for a quality expression of it.
There was, without exaggeration, only one cafe that knew what a real cappuccino or ristretto espresso was. This was back when ristretto was still the ‘in thing’ to say and do. Oh, the good ‘ol days. Mr. Delazzer, thanks for inspiring me then, and for continuing to do so…
For all of you who have not read Aaron’s famous Milk Frothing Guide, you should do so at some point; it is a necessary feat for anyone aspiring to a black-belt in coffee. While that article was in many ways the predecessor to this one, I will take a more elementary approach; and therefore, this article will appropriately serve as a something of a preliminary to that one. This is, after all, The Basics. Once you crave more, follow this link.
There are probably many strongly held opinions about whether making espresso or steaming milk is more difficult. I will say this, I think that milk is the hardest skill to learn, yet the easiest to master. Once you have it, you have it forever, unless you get sloppy. Conversely with espresso, the skills required to pull a shot properly are quite straightforward (even tamp, even dose…), but I don’t think one can ever master espresso. There are simply too many factors that one must be in constant evaluation of. Each day is a new day, coffee 10 days off roast is so much different than 3 days off roast. I’ve never heard a barista say, “I can’t work with this milk, it’s 9 days old and I need 6 days.” Still, milk is very tricky. There are far too many baristas satisfied with sub-par milk that lacks proper texture and sweetness. Dare I say that what truly distinguishes a quality cafe is the quality of its milk? Think about it. Although espresso is so frustrating in that we can’t perfect it, we are quite able to get a decent shot. It may not be perfect every time, but when you dilute it by a 5:1 ratio (or more) with milk, a lot of the subtleties becomes subdued. Furthermore, milk is something that almost everyone experiences when they order a bar drink. No one is contemplating whether the 30% Yirgacheffe component in the espresso is too aggressive when they order a mocha. But if that same person spends over 4 bucks for a drink and they scald their tongue, or the foam looks so light and pillow that it would float away if the front door is opened, I should hope that that customer-cafe relationship is quickly put on thin-ice. People deserve better than that, and baristas can and should produce better drinks.
So how does one achieve amazing steamed milk? I think the whole process can be broken down into three very basic but incredibly essential principles. Rule No. 1) The uppermost surface of the milk must be constantly forced downwards. Rule No. 2) When injecting air (making foam) try to do so without actually making milk bubbles. In other words, you should be introducing the air so evenly that you cannot see the bubbles, as opposed to making dish-soap like froth for a few seconds and then trying to distribute it evenly. Rule No. 3) Stop injecting air once the milk is above body temperature (i.e. feels warm at all).
Rule No. 1: It is incredibly important to have constant motion in the pitcher; but not just any agitation will suffice. Air is lighter than milk. So it wants to migrate to the top of the pitcher. The only way to get homogenous micro-foam, which is a very fickle and temporary coexistence of both steamed milk and foam, is to force its coexistence. You must prevent ‘dead spots’ from forming; these are zones on the surface of the milk that are not circulated with the entirety of the pitcher. The result is stiff, dry, foam. This is particularly noticeable with lower fat milks, especially skim milk. The surface may appear smooth, but when you attempt the pour, the milk pours out in a nasty blob. This blob is your enemy. A common habit that some baristas have when they start out is to tip the pitcher towards the machine. Though you can still get great foam this way, I think it’s the hardest way to steam. Instead, I would recommend tilting the pitcher towards yourself, and just slightly to either the right or the left. This asymmetry is very conducive to a good whirlpool effect in the pitcher. That whirlpool is what will properly circulate the milk.
Rule No. 2: This should be fairly obvious. If you don’t want big, frothy bubbles at the end of steaming, don’t put them there in the first place. Keep in mind rule No. 3, though; act quickly. You must steam the milk as forcefully as possible, without producing big bubbles. Try to allow the steam tip to just barely break the surface of the milk. Also, keep it relatively close to the center; if you keep the tip at the side of the pitcher, you lessen its effectiveness to force the milk down, and produce the proper amount of foam quickly.
Rule No. 3: Cold milk is your friend, and your time with it is short; don’t waste it. The proteins and fats are most capable of forming the super-small bonds that allow for micro-foam when the milk is cold. A good rule of thumb (or hand?) is to ensure that you inject all the air you need before the pitcher feels warm. The next 10 seconds or so are strictly about making that smooth foam even smoother. And please, don’t shove the pitcher up and cause the steam tip to be suffocated at the bottom of the pitcher. Don’t forget rule No. 1! It applies through the entirety of the process. The steam tip should always be near the surface of the milk, this is the only way to keep the whirlpool going and to draw the surface of the milk to the bottom of the pitcher.
Hope that helps. Like I said, in my opinion, this is the hardest thing to learn. While this article might help, the best way to learn is to watch someone do it properly, practice until you either have it mastered or are ready to quit, then go back and watch them again, and keep practicing until you get it.