NPR interviewed David Hockney who has been using his iPhone and iPad to create drawings with the help of a painting app called Brushes. The 73-year-old artist recently held an exhibit of his new artwork in the Pierre Berge-Yves St. Laurent Foundation in Paris. Hundreds of digital works were displayed on 40 screens (20 iPhones and 20 iPads) during the “Fresh Flowers” exhibition that ran through January 30.

Hockney initially became intrigued by the process while observing the morning sun enter his bedroom in Yorkshire, England. He would dip his fingers into the virtual paintbox on the phone’s screen, “paint” some flowers digitally in the morning light, and email to friends. “Incredible little thing, really, because it was like a sketchbook and a paintbox all in one,” the artist says. “No cleaning up. No mess.”

When he made the switch from the iPhone to the larger iPad, Hockney was able to expand upon his work and found he could use more fingers to create his art. Now he travels with the iPad as a substitute for the sketchbooks he always had with him. Old habits die hard, though. “He says he sometimes gets so obsessed that when he’s going, he rubs his finger on his clothes to, like, clean his finger — as if he was using real paint.”