I have read roasting tips given as "first crack + 30", "second crack + 10", or "beginning of 2C" ...etc. But when do we decide the exact start of a first crack or second crack and begin the counting? Is it when we heard the first "pop" or when the "pops" are starting to be more frequent?

There could be anywhere between seconds to half a minute or even longer before the popping increase in frequency. In some cases, a few pops are all that we get. I personally decide when a crack (first or second) starts and count the seconds from the moment I heard the first "pop" but I have heard others say that they wait until it becomes more frequent then start counting the seconds.

Generally, We consider 1st crack as just after the outliers crack. Oh course a lot about sharing roasting instructions is very subjective and need to be considered as such. There are so many variables that must always be considered. 20secs in a fast heat transfer roaster will be very different than 20secs in a slower roaster.

Ending roasts on time does not lead to consistent results, unless you have the roaster automated. Use the appearance of the beans, their smell, and thermometer readings as the mile stones for adjusting the heat and ending the roast.

The cracks work like an alarm bell, in case you are snoozing

uranium wrote:...I personally decide when a crack (first or second) starts and count the seconds from the moment I heard the first "pop" but I have heard others say that they wait until it becomes more frequent then start counting the seconds.

HI UT
I'm in the latter category - not the first odd pop or two, but at onset of more frequent...the same applies to the question ''When does 1st crack end?'' I have been logging it as the last group-cracks not an odd one or two stragglers.

Thank you all for the very helpful insights.

Not sure how helpful we were, and a thought I had later about this was that the purpose of watching for 1st and 2nd is to understand the process better, shape the roast better, and end our roasts at the moments we choose to produces better and better coffee.

I think the key would be to be consistent no matter which method you employ. My method wasn't arrived at by other's opinions, but by experience, and learning to read the symptoms of the roast.

Hope you find what you need...