| 摘要 |
633,899. Photo-mechanical printing-surfaces. ERARD, A. Aug. 1, 1947, No. 21036. Convention date, April 25, 1945. [Class 98 (ii)] To obtain fine detail on a photo-mechanical etched intaglio metallic printing-surface, or in the production of die-stamps or of scale graduations on metallic parts, the negative from which is copied a positive used to expose a lighthardenable enamel applied to the metallic surface which after exposure is etched, for example with ferric chloride, is produced by employing a camera having a focal distance not greater than 80 mms. If the object to be photographed is small an enlarged photograph may be made, corrected by hand and then copied at a reduced size by means of such a short focus camera. |
