Rubylith RM3 is a high-tack ruby film coated onto 300-gauge polyester. Each Sheet is 15 x 20-inches. As shown below, Rubylith is normally used in graphic arts and screen-printing industries, however, it is an excellent product for amateur astronomers as well. Rubylith will produce very consistent results when used to create a night-safe red light out of normal white lights, unlike most "quick-fix" materials we've tried, such as red tape, paint, and thin cellophane. Since it is bound to 300 gauge polyester, it holds it's shape well when cut and is easy to work with.
Rubylith is a red masking film, which is suited for use with orthochromatic films. Rubylith 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, flexography, gravure, and screen processes where orthochromatic films and plates are used.
Rubylith brand masking film is a light-safe knife cut film coated onto a polyester backing sheet. These films can be cut manually or on a plotter to produce masks for film contacting and plate making and film positives for photographic stencil production.