Understading Flow Convection

I believe many people seen Master Junichi’s Latte art and questioned, “How is he doing this?”

I am here to explain that, this is no magic, is all “Physics”. One needs to have deep understanding of how liquid flows naturally for this sort of latte art.

I believe most people realize that this sort of art is everywhere in Japan and only in Japan. But Mr.Cabell Tice from USA had won multiples Latte Art championship in Coffee Fest over the Japanese. Mr. Huan Lin from Taiwan manage to fight his way to the semi-finals against these talents. So let me emphasize this. Everybody can do it! Country has nothing to do with it. It is up to you to do it.

Coffee and Crema

Firstly I have to explain why their milk seems to flow so well. The coffee plays into account. If you realize the crema of their coffee seems to be flat, silky, shiny and almost slippery.

Only this sort of crema allows milk foam to flow freely on the surface. Most of us are unable to do what they do mainly because of the coffee. Not all coffee produces the same sort of crema. For example, Catimor and Robusta tends to have thick rough looking crema.

This sort of rough crema will stop milk from flowing in everyway. So what are they using? Brazilian coffees. Most Brazilian coffees are bourbon. Bourbon tends to have thin and silky crema no matter light or dark roasted. Catimor and robusta on the other hand almost always produces thick and rough crema. However, this will also varies on roast level.

There are many brewing/roasting methods to manipulate the crema of your espresso. The hard part is to make a perfect looking crema while not disrupting the taste of your coffee. You will need a deep understanding of espresso to achieve this. That is why using the right coffee just makes life so much easier

Pitcher

There is no coincidence almost every barista in Japan uses Rattleware milk jugs aka RW.

Shape of the base, the wall, the beak and the weight of the pitcher affects every aspect of how milk flows. RW pitchers are deemed to be ideal for natural flowing. I have no clear explanation for this. The best way to explain will be Kalita/Takahiro’s pour over kettle versus Hario’s kettle. So to be able to pour the Wing Tulip, you NEED a RW, or atleast something similar like Yami or Timemore.

Milk Steaming

To maximize natural flowing, the milk foam should be as thing as possible. When the milk flows out from the beak of your milk jug, it should be running almost like water, not whipped cream. As thin as it is, you need to make sure it still creamy, or else pouring any art will be impossible and at the same time, your cappuccino will taste awful. The quality of milk foam has to be PERFECT. NO EXCUSES. If you still cannot do it, practice! Practice makes perfect. Just keep trying until you get it.

The Pouring

Now if you already got the crema you desire and had already mastered your milk steaming techniques. We can finally move on to pouring.

BLACK LINE the base of the cup, GREEN LINE is the end of the curved zone of the cup. Beyond the green line I will called it the SAFE ZONE. This will come in play later on.

WHITE ARROWS = water flows direction

RED ARROWS = obstacles redirects flow

Note: the closer you are to the obstacle, the stronger it will redirect. The further you are away from the obstacle, the less effect it will give. We call this, flow convection. The speed of pouring will have a direct effect on the flow convection too. Hence, the faster you pour, or the closer you get to the obstacle point, the stronger the flow.

Slowly swing your milk jug through. You want the milk to flow out on its own, so be gentle.

Keep swinging your milk jug until you are close to the safe zone. As you swing, lines should slowly move outwards.

As your cup is filled closer to the safe zone, slowly push your milk jug forward while lifting it up. This will redirect the lines back to where it started. Doing this will create a gap between the lines.

This is very important, if you do not make a gap between the lines, you will just get random line for the base of your tulip. The lines will not wrap around your tulip and your tulip will not look like it had a pair of wings.

Then pour a circle right into the gap. This will push the lines outwards, forming the “Wing”.

Then you may proceed to finish up your tulip in whatever shape you like!

Few end notes. Why do I mention the SAFE ZONE .

Because at the point, is where the flow convection is at its lowest. If you stop swinging mid-way before hitting the safe zone, there is a high-chance your lines will be deformed and the base of the lines will be flat instead of perfect round shape.

If you stop at this point of the pouring, the walls of the cup are still in play. Unless your hand stay still before you pour again, any hand movement should affect the pattern of the lines.

Most common ones are what I called FLAT BASE.

We tend to tilt the cup into a horizontal position as we pour. But if we do that while not pouring

The bottom wall will push the flow upwards, and distort the shape of the lines.

Other way to prevent this is start pouring your lines when your cup is more filled for lesser flow convection. This will give you better contrast, thicker lines, and less likely to make mistakes .

Starting early better flow convection, wings warp around the tulip better, finer lines, and much more beautiful. In exchange, you are more likely to make mistakes.

Here is a picture of my own work, took me a year from knowing how to pour a basic tulip into this. I know it sounds really long, but I had to figure out all these details by myself by experimenting.

Practice makes perfect. I don’t expect anyone to be able to do it right off the bat from reading this. But this guide should at least help cut your progression speed by half.

The main reason I made this guide is that I see too many barista are blaming their local milk for not being capable of doing the Wing Tulip. Well, me and my friends made it here; with the same milk everyone else is using. If we can do it, so can you. It takes time, but definitely worth it. So good luck folks.

Pictures are taken from Master Junichi’s video and edited by Han Wang,

Author,

Han Wang

DOWNLOAD : How to Wing.pdf