Pre-infusion

A brief, low-pressure stage that wets the coffee bed before full brewing pressure arrives.

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How the shot starts

What it means

A brief, low-pressure stage that wets the coffee bed before full brewing pressure arrives. It gives the puck a head start — grounds expand and settle before the machine drives them under force. This often improves evenness on lighter coffees or when the shot would otherwise surge too aggressively at the start.

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Where this leads

Each one pushes this into the cup, compares it, or helps you act on it.

Before the water hits

Channeling

A gentle start is usually there to prevent uneven paths through the puck.

Treat puck prep as part of extraction, not as a ritual before it.

Before the water hits

Puck

Pre-infusion only helps if the puck can respond evenly under pressure.

Think of the puck as the extraction environment, not just the spent material left after the shot.

What you see in the shot

Flow Rate

The first visible effect of pre-infusion is how the shot begins to flow.

Watch the flow as well as the scale. Good espresso gives multiple clues at once.

What people mean when they say "extraction"

Espresso Extraction

Then connect that smoother start back to taste and balance.

Separate extraction from strength in your thinking. One asks how much was dissolved, the other how concentrated the drink feels.