File:Anthony's photographic bulletin for (1896) (14595424177).jpg

Identifier: anthonysphotogr1896newy (find matches)
Title: Anthony's photographic bulletin for ..
Year: 1870 (1870s)
Authors:
Subjects: Photography
Publisher: New York : E. & H.T. Anthony & Co.
Contributing Library: University of Illinois Urbana-Champaign
Digitizing Sponsor: University of Illinois Urbana-Champaign

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s with a grainscreen, however, will be uncertain to a degree, for the size of each dotof grain cannot be controlled with the precision that is the chief meritof the regular half-tone screen. Grain screens have been made in this country by dusting a finepowder of asphalt on plate glass, as in the grain zinc etching processor in photogravure, only substituting plate glass for the zinc or copperWhen the grains of asphalt were heated sufficiently to attachto the- plate glass, the latter was copied in the camera,giving a negative with irregular transparent dots, which was used as ahalf-1 11 The drawback to the use of irregular grain screens was found, notonly in tin- ac< idental nature of the grain obtained, hut in the fact that in the high lights, where the dots should he smallest, all the small dots leaving only the largesl dots widely separated, and,equenth i bli i ffeel on prinl ing. er Shepherd has laid before the Royal Photographicll of hi i ;ueful experiments in the produclion of
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,25 irregular grain screens and in the securing of relief blocks therefrom.He has studied the subject more thoroughly than any one before him,and his conclusions cannot but be of interest. The best method ofmaking an irregular grained screen is : By flowing an aqua-tint ground over a sheet of glass, etching in with hydrofluoricacid, then repolishing the glass to insure a perfectly clean surface, and filling in withprinting ink, so that the screens are perfectly permanent. And in the event ofinjury by nitrate of silver or otherwise, the old filling can be washed out with benzoleand refilled with fresh ink. There are three kinds of screens which may be used : (i) An etched screen,which is the most generally useful ; (2) a copy of an etched screen on a dry collodionplate, which I do not recommend, as it is liable to stains and a slight veiling of thewhites ; (3) you may use a bitumen grain laid on the plate and heated, but this kindof screen is only useful for photo-lithographic work, be

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