Microfoam

Microfoam is steamed milk with bubbles so small they are barely visible, giving the milk a thick, glossy, paint-like texture instead of the large dry bubbles found in loosely frothed milk. It is the texture used underneath latte art and is what makes a latte or cappuccino feel silky rather than airy or watery.

Making it well means introducing air into cold milk early in the steaming process, then submerging the steam wand to spin the milk into a smooth vortex that breaks the bubbles down further as the milk heats. Milk that is too hot loses its ability to hold fine foam and can taste scalded, while milk stretched too long turns dry and foamy instead of glossy.

A pitcher with a narrow spout makes it easier to pour microfoam in a controlled stream for latte art, and a milk thermometer helps avoid overheating, since the ideal range is usually around 140 to 150 degrees Fahrenheit. A common mistake is stopping the steam wand too early, leaving large bubbles that never get broken down into true microfoam.