Ethiopia Guji Karume — Natural
Date: 8th Feb 2026
Roaster: Gene Café CBR-301
Batch: 250 g
Set temperature: 250 °C
In / Out: 250 g → 214.8 g
Weight loss: 14.1%
Total roast time: ~18:32
Intent: Repeatability check on Ethiopian natural; confirm crack behaviour and Lazy Mode boundaries
Why this roast exists
Roast 17 exists to test repeatability, not improvement.
Earlier roasts established that Brazilian naturals often produce quiet or smeared first crack, while Ethiopian naturals can restore a clear, rolling crack without any system change. Roast 13 demonstrated this clearly. Roast 17 repeats the same coffee to confirm whether that behaviour holds and whether time and weight loss remain reliable anchors even when crack is obvious and tempting to chase.
This roast is about confidence, not novelty.
What happened
The roast progressed calmly and predictably.
First crack was clearly audible and rolling, with a noticeable rise in intensity shortly after initial onset. The peak of the crack occurred roughly 15 seconds after the moment it was first recognised, reinforcing the idea that crack onset and crack intensity are not the same event.
Cooling was initiated approximately 80 seconds after a rolling crack, based on colour and aroma rather than sound alone. The roast finished at 14.1% weight loss, landing squarely within the established Lazy Mode development band.
Colour was even and medium, with no visual signs of overdevelopment. Aroma at drop was warm and sweet, leaning toward chocolate rather than sharp or smoky notes.
What this confirms
This roast reinforces several patterns that have already begun to stabilise:
- First crack audibility on naturals is coffee-dependent, not system-dependent.
Ethiopian naturals consistently produce clearer crack behaviour than Brazilian naturals on this setup. - Audible crack does not imply deeper development.
Despite a confident, rolling crack, the roast landed cleanly in the mid-development range. - Time and weight loss remain the most reliable stop cues.
Crack was descriptive rather than decisive; the roast did not require a different strategy because it was louder. - Lazy Mode boundaries hold even when crack is clear.
This roast validates that the same stopping logic applies whether crack is obvious or ambiguous.
How this sits relative to other roasts
- Compared to Roast 13 (Ethiopian natural): behaviour is consistent; crack clarity returns without system change.
- Compared to Roasts 14–15 (Honduras Catuai naturals): similar development level, but with more pronounced crack.
- Compared to Roast 8 (Brazil Topazio natural): entirely different sound behaviour, reinforcing Roast 8 as an upper-bound contrast rather than a failure.
Roast 17 adds confidence rather than new complexity.
What this does not change
- Lazy Mode defaults remain unchanged.
- Crack is still not treated as a primary decision trigger.
- This roast does not introduce new rules or targets.
Its value lies in removing doubt, not adding technique.
Provisional takeaway
Even when first crack is clear and confident, Ethiopian naturals on this system still land cleanly when time, colour, aroma, and weight loss, not sound, define the stop.