There is a single visual test for whether milk is ready, and it is reliable.
What good looks like
Glossy. The surface reflects light. A shine is the clearest single indicator.
No visible bubbles. Not small bubbles — none. Any bubble you can see is far larger than microfoam.
It swirls as one mass. Rotating the jug, the whole contents move together. There is no separate foam layer sliding over liquid beneath.
It coats the jug wall and leaves a thin film as it swirls, like paint.
What bad looks like
Matte and dull — too much air, insufficiently sheared.
Bubbles on the surface — over-stretched, or air added too late.
A visible foam layer moving separately — the vortex phase was skipped.
Thin and flat with no body — not enough air. It will disappear into the espresso with nothing to draw.
Fixing it in the jug
Bang the jug hard on the counter two or three times to pop large bubbles.
Swirl continuously until you pour. This keeps it integrated and adds a little polish.
Neither turns stiff foam into microfoam. They are finishing touches, not rescues.
Pour immediately
Even correct microfoam separates in 60 to 90 seconds. Swirl until the moment of pouring.
The practice trick
Water with a drop of washing-up liquid textures much like milk and costs nothing.
Last reviewed 8 August 2026