Metric Coffee · Colombia Carlos Efrain Cortes

Shot 80 on the Colombia Carlos Efrain Cortes — grind 34, 15 seconds, 37g yield at ratio 2.13. You went 6 clicks finer from the first shot (grind 40) and the flow barely changed: still 15s Very Fast. The lingering sourness and thin body you noted are consistent with severe under-extraction. This light roast, high-altitude washed bean is significantly denser than Unicorn Blood and needs a much coarser starting point than your muscle memory suggests.

15s is Very Fast — well under the 25s floor for Normal. Ratio 2.13 is Normal. The mismatch between time and taste (lingering sourness, thin body) aligns perfectly: the grind is nowhere near fine enough to slow this dense bean down. Worth flagging: your lag reading of 17g this shot is higher than your established 6–10g Bambino norm — worth a quick check next session to confirm the portafilter was fully locked and the basket seated properly, though one anomalous reading isn't a concern on its own. Two shots at grind 40 and 34 both ran 15–16s — the grind range you've been working in simply doesn't apply to this bean. Light roasts at 2015m elevation resist extraction hard; the Unicorn Blood is medium-dark and extracts much more readily at grind 40.

Colombia Carlos Efrain Cortes is a light roast washed single origin at 2015m — some of the densest bean structure you've encountered in your log. At 12 days post-roast it's right at the start of its peak window (light roasts typically peak 14–42 days), so it's borderline fresh — which can contribute to slightly faster flow and less flavor development. Tasting notes are Limoncello, Blackberry, Cocoa — the lingering brightness you're tasting is partly bean character, but lingering sourness at a 15s shot is genuine under-extraction, not just acidity. Your closest reference is Coffee Lab Huila Decaf, which also choked at every grind finer than 33 before finding life at 38. The analogy isn't perfect (decaf extracts more easily, not less), but the lesson applies: dense light roasts require dramatically different grind settings than your dialed-in medium-dark beans.

Two shots, both 15–16s regardless of grind setting — this bean is telling you clearly that your entire current grind range is too coarse. The good news: you've navigated this exact situation before with Coffee Lab Huila Decaf and Brazil Cerrado. The pattern recognition is there.