Rubylith is a red masking film, which is suited for use with orthochromatic films. It is "safe" for use with camera speed darkroom films as well as indirect gelatin stencil films and diazo, diazo acrylic, or SBQ sensitized stencil films or emulsions. Rubylith is primarily used in the camera and plate making operations for offset lithography, lexography, gravure, and screen processes where orthochromatic films and plates are used. Rubylith has a single tack level and is coated as RU3 on 3 mil (75 µm) and RU5 on 5 mil (125 µm) polyester.