Only use stainless steel jugs when attempting to foam milk. Never use plastic, glass or china jugs. Stainless steel offers good heat transfer which is an essential part of the process.

Always use chilled fresh milk - milk will take in air easier if it is cold. Full fat milk produces a denser, longer lasting foam than low fat milk, but this is personal preference.

As the volume of the milk foam mixture will expand to nearly double its original size, make sure you only half fill the jug to begin with.

The first thing to do is to purge the steam wand of any water residue, making sure that none of the steam jets are blocked and position the wand so that it will allow the jug to easily pass under the tip.

The tip of the steam wand should be placed about 1 cm below the surface of the milk and in the centre.

Turn the steam valve fully on.

Holding the jug in both hands, gently adjust the depth of the wand tip until you hear a distinct "tssss tssss" sound which indicates that air is being drawn into the milk. As the milk is 'stretched' or expanded the milk level in the jug will rise swiftly. As this happens, lower the jug slowly, keeping the tip just below the surface at all times.

If the milk bubbles too fiercely and spits then the tip is too high and you should raise the jug slightly, however if you hear a screech then there is insufficient volume of steam so you should lower the jug slightly.

During this process try to avoid breaking the surface of the milk with the tip as this can introduce large bubbles into the mixture and spoil its texture.

To complete the process, lower the tip of the steam wand (by raising the jug) towards the bottom of the jug and at the same time move the wand to one side of the jug. The milk should start to swirl and you should here a high pitched growl. This adds texture to the mixture as many tiny bubbles are formed.

Continue to swirl the milk in this way until the side of the jug is too hot to touch comfortably and the growl becomes a low purr. Turn off the steam quickly with the wand tip still submerged.

The wand should be removed from the mixture and cleaned.

Tap the jug on the counter and swirl the jug around gently. You should have a jug of firm, velvety foam over hot steamed milk.

Pour the mixture over an espresso by gently rocking the jug from side to side to ensure the right combination of hot milk and foam is delivered into the cup.

Enjoy.