Most home baristas over-correct because the symptom is misread. This guide separates taste faults so each fix is deliberate.
Sour, sharp, or salty shots
These signals often indicate under-extraction. Start by grinding finer or extending yield slightly.
Also verify brew water is hot enough and your machine is fully warmed up.
Bitter, dry, or ashy shots
These usually indicate over-extraction. Grind coarser or shorten yield.
For darker coffees, lowering brew temperature can reduce harshness.
When both sour and bitter appear
This can point to channeling. Improve distribution and tamp consistency before changing recipe again.
Use bottomless portafilter feedback if available to spot uneven flow.