What tastes wrong?
Bad cups usually come from extraction balance, not "bad beans." Choose the taste problem and method; the tool gives one controlled next change so the next brew is comparable.
What the tool fixes first
| Taste note | Likely direction | First useful change | Keep steady |
|---|---|---|---|
| Sour, sharp, hollow | Under-extracted | Grind one step finer or extend contact time | Same ratio |
| Bitter, dry, harsh | Over-extracted | Grind one step coarser or shorten contact time | Same dose |
| Weak, flat | Too little extraction or too much water | Check grind first, then tighten ratio | Same water amount |
| Watery | Too much water for the dose | Use more coffee or less water | Same method |
| Muddy, silty | Too many fines or too much agitation | Coarser grind, gentler pour/stir | Same ratio |
After the next brew, save the method, ratio, grind, time, and taste note in the journal. Pair this with the grind size chart and ratio guide.
Method examples
| Method | Bad cup | Change next brew |
|---|---|---|
| V60 | Sour and finished under 2:00 | Grind finer; keep 1:16 |
| French press | Bitter and silty | Grind coarser; press gently; pour off the grounds |
| AeroPress | Weak after dilution | Dilute less first; then tighten ratio |
| Cold brew | Heavy and bitter | Shorten steep or grind extra coarse |
| Moka pot | Burnt and sputtering | Lower heat and remove earlier |
Change only one row at a time. If you change grind, ratio, and temperature together, the next cup will not tell you what worked.