Like many, I've been experimenting with the roasting guidelines proposed in "Coffee Roaster's Companion." For me, this is producing good results at light roast levels.

I am interested in going a little darker for some beans, but I'm not sure how. Assuming I want to keep a declining ROR throughout the roast, and that I want to keep my development time (post 1C) ratio at 25%, I see two approaches. First, I could charge at a lower temperature, thereby lengthening the total roast time but keeping a similar ROR curve. Second, I could keep the same charge temp, and try to manage the heat input such that the ROR curve is a little flatter, thereby squeezing a higher final temp out of the same total roast time.

I am going to try both, but I thought I'd ask the group: which of these approaches are most likely to work best? Am I missing something else to try?

For reference, I'm on a Quest M3 roasting 225g batches. I am interesting in going to FC+.

Thanks for your thoughts!

I would not flatten out the curve. Instead, I would shorten the time to FC, using slightly less airflow, and cut back somewhere toward the middle of FC and ride the temperature steadily down to finish. Slowing down too much and going darker will just make your roast ashy.

While this is good advice in general (I too have had good luck accelerating the mid phase), it doesn't help acheive this particular goal. Getting to 1C faster will surely increase my time time ratio after 1C to be higher than 25%.

Is anyone using Rao's "rules" and doing dark roasts?

I recently did a roast of the blend of Central coffees I roast often with 25% development phase. That was 10 minutes to first crack and finish roast by 13:20 at FC+ which is exactly 25% development. This roast was inferior to roasts of same coffee where I get to first at 10 minutes and finish roast between 14:30-15:00 minutes for FC+...

I wanted to post a quick follow-up for those who may be interested, and for future forum searchers.

For me, the best results came by lowering the charge temperature. This lets me use the same power adjustments and the same overall ROR curve, while giving the whole roast a little more time to develop.