Mark Lewis (left), chief conservator at the Chrysler Museum of Art, recently led a fascinating behind-the-scenes tour for Rotarians. He explained the detective work that goes into discovering the history of paintings and properly repairing them, including peering through a microscope and using ultraviolet light to study what is under the top layer of paint.  Fun facts: Lewis and his team use handmade cotton swabs on chopsticks with a natural solvent to gently remove dirt from paintings. And, if they touch up a painting they always use watercolors so their work can be reversed.