A drum, a thermocouple and a notebook. These are the terms I keep having
to pin down when comparing one batch against another.
First crack
An audible snapping around 196 °C as steam forces its way out of
the bean. Everything before it is drying; everything after it is the
part that actually decides the cup.
Development time
The share of the roast that happens after first crack. Short keeps the
acidity sharp and the body thin, long trades both away for sweetness
and, past a point, for ash.
Degassing
Two or three days of rest while carbon dioxide leaves the bean. Brew
too early and the bed keeps lifting in the filter, and the extraction
comes out uneven no matter how the grind is set.
Charge temperature
How hot the drum is when the beans go in. Sets how much heat the batch
carries through drying, so changing it changes everything downstream.