| 摘要 |
850,047. Photographic screens and graticules. GRATICULES Ltd. June 18, 1959 [Sept. 15, 1958], No. 29436/58. Classes 97(1) and 98(2) Screens of the kind comprising a glass base and a pattern thereon as of a half-tone or gravure screen or a graticule are made by forming a photographic image thereof of a metal of the platinum group in a collodion emulsion on a glass support, treating it with an aquous solution of a soluble salt of tin, bismuth or lead, and then burning off the collodion to leave the image firmly adherent to the glass. As more particularly described and exemplified a glass plate is subbed with albumen, sensitised with silver nitrate and green ferric ammonium citrate in the collodion with methyl alcohol as solvent, exposed, developed in water, immersed in a solution of potassium chloroplatinite or chloropalladite, washed, transferred to a solution of silver nitrate with hydroquinone for intensification, retreated with the platinum metal salt and then treated in an acidified bismuth or lead nitrate solution, bathed in dilute aqua regia, washed and heated briefly as to 500-600‹C. to burn off the collodion and the subbing layer before the glass is unduly heated.
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