thinkwell. roaster, Erik Johnson explains coffee roasting in terms of temperature instead of the light and dark roast categories you may have seen throughout the industry. thinkwell. came to use finish temperatures as a way of explaining the unique character of each roast. Using finish roast temperatures communicates to the coffee drinker something objective about the roast development and flavor of the cup. Describing coffee in terms of roast temperatures also serves as an introduction to understanding coffee roasting.