Blue Bottle Coffee · Night Light Decaf

Shot 104, grind 38.5, ristretto target hit (28.6g yield, 20s). Balance 2, lingering sourness — same outcome as the previous grind 38.5 shot. The left-side drip note suggests distribution wasn't clean, which may be compounding the under-extraction.

Time is Fast at 20s and ratio is Short at 1.55 — both consistent with a ristretto pull. The taste doesn't match what the numbers predict: at 38.5 your last confirmed good ristretto was at 40.5 (balance 4, 17s), meaning you're already 2 clicks coarser than the dialed-in setting. Sourness with linger at 38.5 confirms the known_patterns finding — coarser is definitively worse on this bean. The left-side drip mid-shot adds a distribution variable that could be suppressing extraction further.

Night Light Decaf is 24 days off roast and still in its peak window (Swiss Water decaf, medium roast — typically good through ~day 28). Freshness isn't the issue. This bean has a clear pattern: it rewards finer grinding despite being a decaf, and its flavor profile (smoky, strong, crème brûlée) is assertive enough that any under-extraction reads as sharp sourness rather than brightness. The confirmed dialed-in ristretto grind of 40.5 is your anchor — treat 38.5 as disqualified.

The 40.5 ristretto baseline you locked earlier is holding up as the reference point — every deviation coarser has confirmed it. The work now is getting 36.5 tested clean so you have a finer-end data point and can triangulate whether 40.5 is truly the floor.