| 摘要 |
966,129. Etching. KASTANNUSOSAKEYHTIO OTAVA. Feb. 22, 1963, No. 7338/63. Heading B6J. In a method of etching a printing cylinder in relief, the text and pictures are printed on pigment paper which is attached to the cylinder and developed; the thicknesses of the developed gelatine relief corresponding to the darkest and lightest tones are measured, either directly, by taking a test-piece from the relief, or by a test strip, on which the strongest and weakest densities of the toning surfaces are used, falling on a transparent strip fixed on the cylinder; a mathematical model is then calculated from the above measured data, giving the relationship between the initial specific gravity of the etching liquid, and the amount of water to be added at various times. The cylinder is then etched with ferric chloride solution according to the resulting formula. |
