| 摘要 |
<p>446,777. Printing-snrfaces. BOEKELMAN, W. A., 11, Prins Hendrildaan, Bilthoven, and ELFERS, A., 5, Hyacinthlaan, Haarlem, both in Holland. Jan. 26, 1935, No. 2654. Convention date, Feb. 15, 1934. [Class 100 (ii)] [See also Group XX] A printing-plate for offset printing comprises a thin upper layer of ink-retaining metal applied over a naturally water-retaining surface of lead or of a lead alloy, the upper layer being etched through to expose the under layer with an agent which does not affect the latter. In carrying out the process, a layer of lead or lead alloy is coated with a skin-thin layer of copper, e.g. of thickness of the order of À005 mm., by electroplating. A design is then applied to the copper, e.g. by the albumen or cold enamel process and the copper etched through to the underlayer. Re-etching to modify the tone values may be applied locally, the parts which it is not required to treat being protected with paint and grease chalk which is afterwards removed with turpentine. The whole plate may be treated with gasoline, sulphuric acid, or phosphoric acid before printing. A base of copper or iron may be used as a support for the layers. Specification 446,775 is referred to.</p> |
