Pre-infusion wets the coffee gently
Many machines begin with a lower-pressure or low-flow wetting stage before full extraction. The aim is to saturate the coffee bed more evenly, although machine implementations differ.
Pressure numbers need context
A pump’s maximum rating is not the same as pressure at the coffee puck. Machine design, valves, resistance and user settings all affect the brewing system.
Do not adjust internal pressure valves unless the manufacturer provides a user procedure. Espresso machines combine electricity, heat and pressure.
Use controls after the basics
Flow profiling and adjustable pre-infusion can shape extraction, particularly with difficult coffees. They are most useful after grind, dose, yield and puck preparation are repeatable.
| Control | What it can change | What it cannot replace |
|---|---|---|
| Pre-infusion | Initial saturation | Even distribution |
| Pressure profile | Force through the puck | Correct grind |
| Flow control | Water delivery rate | Fresh coffee and stable temperature |
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