GB453042A - Improvements in and relating to the etching of metals - Google Patents

Abstract

453,042. Electrolytic etching. MALLORY PATENTS HOLDING CO., Ltd., 19, Fenchurch Street, London. Dec. 31, 1935, No. 36050. Convention date, Dec. 31, 1934. [Class 41] [See also Group XVI] A method of etching metal sheets, particularly for use as electrodes in electrolytic cells, condensers, or rectifiers, consists in treating the sheet in an etching bath while in contact with a metallic member, e.g. a screen, which touches it at a number of points distributed over its surface, the metal of the screen &c. member being lower in the electro-chemical series of metals than the metal of the plate so that the etching is assisted by galvanic action. The sheet 9, in the form of a long strip, is first cleaned in caustic soda and then rinsed in water. While still wet it is passed into the etching bath 11 between a fine metal screen 13 on a drum 12 and a second screen 18 passing round rollers 14, 15, 16. It then passes through a washing bath 19 to a winding drum. The faces of the screens not contacting with the strip 9 may be covered with cotton gauze, canvas, sponge rubber or porous semi-hard rubber. For etching aluminium a bath of hydrochloric acid, sulphuric acid, hydrofluoric acid or sodium hydroxide and screens of silver or copper may be used.