Hectograph(redirected from Copygraph)
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a simplified printing apparatus for reproducing text and illustrations. The hectograph is a flat box filled with an even layer of a jellylike mass (a mixture of gelatin, glycerine, and water). The text and illustrations are put on paper by means of a special ink containing an aniline dye, glycerine, and alcohol. The resulting original copy is pressed against the surface of the gelatinous mass in the hectograph, resulting in the transfer of the print from the paper to the layer of gelatin. Subsequently, when blank paper is pressed against the surface of the gelatin, a copy of the text and illustrations is left on the paper. The hectograph makes it possible to obtain up to 100 copies. It was invented in Russia by M. I. Alisov in 1869. The hectograph is being replaced by more efficient devices, including mimeographs and rotaprinters.