Quite simply, a Dark Roast is a coffee that has been roasted further to have a darker color and will finish around Second Crack. A Dark Roast done right is a beautiful thing; big, heavy and bold notes of dark chocolate and toffee. But a Dark Roast gone wrong is a nightmare; bitter, aggressive, gross and notes of death. Nobody wants that. So, how can we get the former and avoid the later?

We are aiming to roast the coffee for longer after First Crack than a Medium Roast (i.e. have a higher development time) and it is personal preference as to how long that is. Our preference is to aim for the VERY beginning of Second Crack… like when we just start to hear one or two beans second cracking. Second Crack is a softer sounding popping noise and is the breaking down of the Coffees exterior. Roasting into Second Crack is where oils start to become present (which we don’t love) and beyond Second Crack is where coffee starts to turn into Carbon and then eventually burst into flame.
The longer a Coffee is roasted the more weight it loses, the more body it has on the palate, the more acidity it loses, and the less sweetness that remains (meaning it will be more bitter). So it’s a balancing act. But our recommendation is to the very start of Second Crack to avoid bitter death and retain some sweetness.
To roast our coffee longer and reach Second Crack without stalling our roast, we will need extra momentum to get to that higher end temperature. So, we will need more heat at the beginning. We suggest charging to a higher temp (not too high that beans get scorched) and keeping high heat up for slightly longer at the beginning of the roast, but nothing too crazy as we don’t want the roast to get away from us. Perhaps keep the gas higher for another 30 seconds before your first gas change, or when you make your first 2 gas changes don’t lower them quite as much. We want extra momentum to get us to that higher end temp while still maintaining our declining Rate of Rise.
Other than your higher charge temp and later or higher first 2 gas changes, your roast profile should be very similar other than letting it develop longer. Think about it like shooting an arrow in Archery. Instead of aiming for the bullseye, we are aiming for the top of the target. We aim our bow slightly higher to get a higher trajectory, but the flight path of the arrow still has the same arching downward momentum. In our opinion, a good Dark Roast is more about finesse than going at it with a sledge hammer (so to speak). Your adjustments shouldn’t be wild to get from a Medium Roast to a delicious Dark Roast.
At the end of the day, you can roast a Dark Roast how you please. There are many ways to skin a cat (as the saying goes). But if you follow these guidelines we think you’ll come up with something good. Have a crack at it and let us know your thoughts!
Tim