Why it matters in the cup.
Coffee glossary
Boiler Pressure
The internal steam-side pressure built inside the machine's boiler.
Filed under
What the machine does
What the machine does
What it means
The internal steam-side pressure built inside the machine's boiler. It supports milk steaming and reflects the thermal state of heat-based espresso systems. Confusing boiler pressure with brew pressure leads to pointless diagnosis — they are related but not the same variable.
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Where this leads
Each one pushes this into the cup, compares it, or helps you act on it.
How the shot starts
Pre-infusion
Machine settings matter most once the shot begins to move.
Use pre-infusion to smooth the beginning of the shot, not to compensate for careless preparation.
The numbers that define the shot
Dose
Pressure diagnosis gets clearer when the puck is loaded consistently.
Use a scale for every dose when dialing in. Precision here saves time everywhere else.
What people mean when they say "extraction"
Espresso Extraction
Move from machine behavior to cup effect.
Separate extraction from strength in your thinking. One asks how much was dissolved, the other how concentrated the drink feels.
How you read the result
Yield
Confirm the change with output, not feeling.
Think of yield as the result you are aiming for and brewed weight as the way you verify you hit it.