The muralist, vehicle painter and graffiti maestro Javier Cordova has a core specialty: lettering. Cordova, who grew up in South Phoenix and goes by “Spawk,” sprays and brushes scripts around Phoenix, often tagging his curvaceous letters on murals and vehicles with gold leaf. His work appears in skate parks, bars, barbershop windows and even Phoenix Suns murals. But you’d never know it. Spawk doesn’t sign his work. “I’m doing it for me,” he says. “If...