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20 bar is not better than 9 bar
Updated
The common standard for espresso is about 9 bar of pressure at the coffee. The 15 or 20 bar on a listing is the most the pump can produce. It is a pump rating. It is not the pressure in your cup, and more of it does not make better espresso.
Why the big number exists
- Small home machines use vibration pumps. These pumps are often rated at 15 bar or more at their peak.
- A valve or the coffee puck itself holds the working pressure lower during a shot.
- A bigger number looks better on a box, so it goes in the title. The CASABREWS CM5418 leads with 20 bar. The two Breville picks list 15 bar and barely mention it.
What too much pressure does
Water forced through coffee too hard finds weak spots in the puck and rushes through them. This is called channeling. The shot comes out thin, bitter and sour at once. So if a machine really did brew at 20 bar, that would be a flaw, not a feature.
What to look for instead
- Pre-infusion. The machine wets the coffee at low pressure first, then ramps up. Both the Barista Express and the Bambino list this.
- Temperature control. Listings call it PID. Steady water temperature matters more than peak pressure. Both Breville picks list it.
- A pressure gauge. It shows if your grind is too coarse or too fine. The Barista Express and the CASABREWS CM5418 have one.
- Basket type. See the grinder and basket guide. This changes your results far more than the pump does.
Warm-up time
Warm-up differs a lot between machines, and listings often skip it. The Bambino listing claims 3 seconds, and owners back up the fast start. Owners of the De'Longhi Stilosa say brewing takes longer than they expected. The CASABREWS listing warns that you must let the machine cool after steaming milk before you brew again. If you make two lattes every morning, that order of steps matters: brew both shots first, then steam.
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