so I finally met in person a local roaster I get most my green from. He is an awesome guy and I have a lot of respect for him and has won a few various roasting competitions. He told me that he waits until first crack and then almost cuts all heat off for about 45-50 seconds to switch from exothermic to endothermic (I may be remembering slightly wrong). And then he urns the heat back on and finishes. I was surprised as this would seem like it would cause the ror to dip And then increase which would seem opposed to common wisdom here. He has a new roaster coming next week that will plot the data similar to artisan, but that was how he was trained and he doesn't know if it ever has a higher ror than the original pre drop ror or not at this point. Any thoughts or clarification for me you could provide?

He even suggested that I might try a light misting at the onset of first crack coupled with a major reduction in heat input, followed by increase in heat, in order to counter the limitations of my stovetop and achieve similar results (said it might not work but something to try)

Without data all anyone can do is speculate, particularly without knowing the specific roasting appliance. Some have such thermal momentum that shutting down the heat for that period may just slow things down a bit with little effect on BT ROR. Hopefully we will be able to see a graph of his method (and ID the new roaster).

My brother in law at 7th Ave roasting told me that they turned their 12k down during first also.

day wrote:He told me that he waits until first crack and then almost cuts all heat off for about 45-50 seconds to switch from exothermic to endothermic (I may be remembering slightly wrong). And then he urns the heat back on and finishes. I was surprised as this would seem like it would cause the ror to dip And then increase which would seem opposed to common wisdom here.

I've been trying to find a reference to this style of roasting but am coming up empty. I believe that I read of a roasting style cutting the heat at first in the article linked from the Nordic Style - What is meant by this for coffee roasting? thread back in 2011, but the article link no longer works. I believe that the article was written by or was an interview with Phillip Search, maybe of Dalis Coffee in Roaster's Realm or the August 2011 Fresh Cup magazine.

Anyway, I remember reading this and also trying this myself in my Behmor for a while. I've since updated my Behmor to the Plus and moved away from dropping the heat precipitously at first crack and from readings of interviews with Tim Wendleboe he's also changed his roasting style as well, but this does sound familiar to me.

Dropping the gas at (or just prior to) FC is pretty common from what I've seen. I don't drop my gas to off on my IR-12 unless I'm only doing a 5# load (6# green in, 5 out).

Keep in mind that larger commercial roasters are charged with a lot of heat already and the idea of shutting off the gas might not translate to a home roaster, especially one that is mostly convection heat. Dropping the gas flow isn't the whole picture when it comes to the heat being applied to the beans. Lots of hot metal is still involved.

A declining ROR BT can be managed this way, but I'm always skeptical about believing probe temps as being ACUTAL BT. I mean, it takes about 1.5 minutes for a probe to start reading BT after 'charging.'

So while the BT probe might not be actual BT the data is still useful and gives you the ability to repeat results pretty well.

day wrote:He told me that he waits until first crack and then almost cuts all heat off for about 45-50 seconds to switch from exothermic to endothermic (I may be remembering slightly wrong). And then he urns the heat back on and finishes. I was surprised as this would seem like it would cause the ror to dip And then increase which would seem opposed to common wisdom here.

First crack is an exothermic reaction, meaning the chemical processes going about inside the beans are releasing energy in the form of heat. He's probably cutting the heat because he does not need the heat provided my the gas to keep the ror consistent. I you are applying the same amount of heat as dry/ramp stages, the beans are now releasing heat, and you have a big commercial roaster with all its thermal mass, your ror would rise, in a worse case scenerio, possibly causing the roast to blow thru 1C into 2C.

Prescott CR wrote:...
Keep in mind that larger commercial roasters are charged with a lot of heat already and the idea of shutting off the gas might not translate to a home roaster, especially one that is mostly convection heat. . .

+1.

As Randy pointed out above, we just don't have enough data to go on here. I reduce heat about 45 seconds in anticipation of first crack. By using Artisan, I can literally see when the steady BTUs are causing a rise in bean mass temp on the graph and I curtail the gas at that time and pick up airflow, as needed.

I am roasting on a North 1K. Too many variables, roasting machine to roasting machine, to take the OP's roaster friend's information as gospel.

With wet process coffees, I lower the gas about 10f before I expect to hit first crack, then I taper it off more after the initial exothermic reaction to continue to slow the ROR, but I would imagine that turning it off altogether would risk baking or insufficient energy to have good development time. Large cast iron drum roasters do store a lot more energy to carry a roast compared to home roasters though....

I k my have one second as I have to get back to work. I understand cutting it down, but cranking it back up?

That stumped me too. I honestly can't think how/why that would be beneficial. Coffee is sensitive while going thru the developmental stage, seems bad.