Like baking or winemaking, roasting coffee is both science and art. A ham-fisted roaster can easily mess up the science and destroy the coffee. But learning how to not ruin good beans is not enough to create amazing coffee. The art dances around the edges; that is where a real artist - using time and heat and other factors - can create sublime roasts that result in a stellar cup of java. This I learned when I recently spent a day with the good folks at Valentine Coffee Roasters, 5918 W. Vliet St.