The idea sounds like fantasy: an invisible film that can be painted on your skin and give it the elasticity of youth. Bags under the eyes vanish in seconds. Wrinkles disappear.

Scientists at Harvard and M.I.T. have discovered that it is not fantasy at all. Reporting on Monday in the journal Nature Materials on pilot studies with 170 subjects, the researchers say a “second skin” composed of commonly used chemicals deemed safe by the Food and Drug Administration can accomplish that — and in small studies of it, so far no one has reported irritation or allergic reactions.