Since we are measure a combo of air and coffee in the roaster, a different ET at FC should yeild a different BT even if the actual temp of the coffee is the same in both cases.

This is so complicated

More complicated than that... We're measuring the temperature of a chunk of metal suspended in a slurry of hot air and beans that's being randomly agitated. But it's better than not measuring.

But don't different coffees crack at different times?

1 crack is always subjective judgement and for every bean in a batch it happens at different time point. It's for sure is not first crack of first bean. Even "1c start " event should be counted when some substantial crackers were observed.

For general 1c need to pick some intermediate point that will be known when 1c will be ended for all beans But here is another problem that some beans could enter to 2crack when others are still finishing 1c

borrik wrote:1 crack is always subjective judgement ...

Agree on subjective. I count 5 cracks and as long as they continue, I count and mark at 5 cracks.

Keep In mind; some roasts have weak cracks at 1st and you may not hear ANY or just a few. Use time, temps (385*), visuals, and smells on those occasions.

Marcelnl wrote:isn't that momentum simply the delay of the measurement, a higher temp increase per minute will have more impact than a lower?

Got it in one.

Since "heat momentum" doesn't exist, the explanation must lie elsewhere. In this case it's the thermal time constant of the roasting setup plus the measurement delay.

Like everyone else said , 1C depends on the beans.... And how much heat you've been putting in and how fast it's approaching. Even the ambient temperature.

You can get a vigorous rolling first crack or you can get virtually no pops at all.

Obviously, you want pops.... And if you have heat to reach 1C in about 8 minutes you will most likely have a good first crack. If your heat is so low you don't reach it till 10 to 12 minutes you may not have any pops at all... Or just a few sporadic. When that happens you need to be prepared to go based on time and temperature..... You might be waiting waiting waiting for the pops and they just don't come.... In which case I might call it at 384 anyway and calculating development time from that. But you got to do that by hand because you already passed the point to market on artisan. So have the chart of development time based on first crack time and write down the time you reach that Target Temp .... In case it doesn't pop. This might happen with changing beans the first time or on a cold day or something like that. .....or... Maybe you goofed the heat in the first part of the batch.... And now the batch ror is proceeding slower than normal...... And it's going to crack late and slower. I've done that a few times. Forgot to turn the heat back on at the right time after charge, etc...

Typically I expect it about 384 F , and it usually lasts up to 2 minutes or so.

Mbb wrote:But you got to do that by hand because you already passed the point to market on artisan.

I believe recent Artisan versions let you right click on a point in the graph and move the first crack point (among other things). So if you think you missed it you can adjust it after the fact.

That would be awesome because not marking the drop or first crack is a not infrequent problem of my version for me. I sometimes I miss it and sometimes it doesn't register when I click it and I don't notice right away.