GB373194A - Process of producing autographic original printing plates or blocks - Google Patents

Abstract

373,194. Printing-surfaces. WEISS, P., Bischwiller, Bas-Rhin, France. Feb. 17, 1931, No. 5014. [Class 100 (ii).] Transfers; transferring designs; etching.- Printing-plates are prepared from original drawings without the use of photography, by producing the original with a special ink on prepared paper, the original being then applied directly to the metal plate to form the printing- surface, which is subsequently grained, burnt, and etched. The original is prepared with a colour consisting of fatty, asphaltic, and alcoholic materials obtained by mixing a greasy autographic writing ink with turpentine oil asphalt, and pigment, a mixture of stearine, talc, and starch, a solution of wax in turpentine oil, and a solution of resin in alcohol being successively added ; finally, a mixture of powdered talc, asphalt and turpentine oil is added. The paper is of fine texture and absorbent and is coated with layers of gum arabic, cellulose lacquer, and gum arabic. The prepared picture is rubbed with a pad of cotton wool soaked in glycerine and the back is moistened with spirit, the picture being then pressed on to the zinc plate which has been rendered adhesive by a solution of resin in turpentine. The paper backing is then removed after moistening and the supporting layers for the picture are respectively removed by rubbing with water, dissolving in spirit and rinsing without rubbing with water. The plate is dried, washed with spirit again, dried and degreased and grained by placing for a short time in acetone. The grains of talc absorb the asphalt and grease of the colour and the spirit varnish is dissolved out, so that the colour is formed into a series of small dots. The plate is removed from the acetone, dried and burnt, and is then etched with dilute nitric acid. The picture is then removed with turpentine and, if necessary, the plate can be further etched with dilute nitric acid, and is finally deep etched.