What's the Purpose of Purging Steam Before Frothing Milk? Important Details to Note Before Latte Art!

Why Do Baristas Purge Steam Wands Before and After Use?

Whenever we pass by a café, besides smelling the rich aroma of coffee, we can often hear the "hissing~" sound of milk being steamed. Watching the busy baristas inside, you might have noticed this action: every time before and after using the steam wand, baristas will purge it for a few seconds, then wipe it with a cloth, and some will keep the cloth over it throughout the process.

Why do they need to purge steam before and after use? Some baristas cover it with a cloth, while others don't?

Why Purge Steam Wands Before and After Steaming Milk?

Purging steam for a few seconds before steaming milk helps raise the steam wand temperature and expel condensed water from inside the wand. This is because when the steam wand hasn't been used for a minute or two, the steam remaining in the pipes gradually cools down and condenses back into water. If this cold water isn't expelled before use and you put the wand directly into the milk pitcher, it will dilute the milk and might even create large bubbles in severe cases.

After we finish steaming milk foam, we need to turn off the steam first before removing the milk pitcher. The surface and steam holes of the steam wand will retain some milk residue. If not cleaned promptly, it will gradually dry and stick to the surface under high temperatures, and might even caramelize. Over time, it can spoil and produce unpleasant odors. Meanwhile, solidified milk will also clog the steam holes, reducing steam output over extended periods.

Therefore, after completing milk foam preparation, it's necessary to immediately wipe these residual milk foams with a clean, damp cloth, and then turn on the steam again to purge for a few seconds to expel as much remaining milk from inside the wand as possible.

Affirmative Side: You Must Cover It with a Cloth!

1. Preventing steam from spraying everywhere and causing burns

You should know that some high-volume coffee shops use commercial coffee machines with two or three boilers. These machines produce very powerful steam. FrontStreet Coffee has seen steam that can spray one or two meters away and fill the entire bar counter as soon as the knob is turned. This not only blocks vision and affects the Espresso being extracted, but also easily causes accidental burns. Therefore, they use a dedicated milk cloth to cover it, preventing steam from scattering.

2. Catching residual milk sprayed from inside the wand after steaming

As mentioned above, some milk remains in the steam wand and cannot be wiped away. If you spray it directly, these milk droplets will splash onto the drain tray below (or the bar counter). Over time, the entire drain tray becomes sticky. Frequently used items like electronic scales and shot cups will get contaminated, and then make the whole bar counter sticky. That's why some baristas cover the steam wand with a cloth when releasing steam after steaming milk.

3. Saving time by wiping and purging simultaneously

Making espresso coffee is all about achieving fast and consistent output. When there's a high volume of orders and intense production requirements, every second saved by combining or eliminating actions becomes incredibly valuable. Therefore, many baristas save time by wiping the milk from the steam wand surface while simultaneously purging steam, doing both actions together instead of wiping first and then turning the knob to purge.

4. A habit developed during initial training

Many beginners using espresso machines for the first time might try it at a friend's shop, or learn through courses... It's inevitable that someone encountering a steam wand for the first time might be startled by its steam output and不敢 touch it, or directly touch the metal surface and burn their hand. Therefore, they're advised to cover it with a dedicated cloth before purging steam. Some training institutions, having encountered such situations frequently, simply require that steam wands must be covered with a cloth when purging. Over time, everyone developed this habit.

Negative Side: No Need to Cover It

1. The milk cloth becomes increasingly damp

Although steam releases gas, it condenses into water when it cools. If you cover it with a cloth every time you purge, the entire cleaning cloth will become damp after steaming just a few pitchers of milk (each pitcher requires two purges), making it very difficult to use. Moreover, if you're not careful, it will start to smell bad over time, especially in hot summer when this happens even faster, requiring constant changing and washing of milk cloths.

2. Just be a little careful when purging

Some coffee shops with low daily output only equip single-boiler, single-wand commercial machines due to demand, and their steam isn't too powerful. As long as you're careful not to turn the steam too high and don't aim it at people, there's nothing to worry about. Therefore, they don't cover the steam wand with a cloth when purging.

3. Afraid of burns? Just don't touch the metal surface of the steam wand~

Most steam wands come with a rubber sleeve for easy handling. If yours doesn't have one, it's no problem - you can buy heat shrink tubing online and put it on yourself. A few dollars gets you five or six meters, which is cheap and effective. Of course, some baristas say they've already developed "iron palms" and don't need to worry at all.

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Important Notice :

前街咖啡 FrontStreet Coffee has moved to new addredd:

FrontStreet Coffee Address: 315,Donghua East Road,GuangZhou

Tel:020 38364473