Typically a polyimide coating thickness of 12 to 15?m is applied to different optical fibers mainly for various high-temperature applications. Because this coating is so thin, handleability is an issue from the point of view of mechanical damage. To protect the polyimide coating from handling-related damage, a composite coating of polyimide and acrylate is typically applied to the optical fiber. We expose such coated fiber to deionized liquid water at 85°C and to steam for durations of 100 d in water and 26 d in steam. When the strength of the fiber is measured after aging in water, there is a slight drop in strength; but, surprisingly, there is no change in strength after aging the composite-coated fibers in steam.