The Dictionary Of Photography

A True Historic Record Of The Art & Practice Of Photography 100 Years Ago.

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Finder                                                 Fish Glue Process
form a conical cup, is placed in a glass funnel and the liquid to be filtered is carefully poured in.
Finder. See View Finder and View Meter.
Fish Glue Process. One of the most common methods of making typographic blocks for representing photographic half-tone as a kind of quarried or lined stipple. The short account here given may not quite serve as a complete guide to the beginner in all complications and difficulties which may arise, but will be sufficient indication as to the way. In the case of a photograph to be reproduced by the fish-glue process, a new negative must be made, and not only must this negative be reversed laterally, but its texture must be broken up in the way indicated. The new negative is usually made from a print - this print being photographed by a camera provided with a reversing prism or mirror before the lens. Inside the camera, and near the plate, is a "screen" formed of a plate of glass upon which cross lines have been ruled, etched, and filled in with a black pigment, the distance of this in front of the negative plate being ordinarily between ^ of an inch and £ of an inch : the criterion of the distance being the formation of a pinhole image of the lens aperture by each window of the screen; but a certain amount of penumbra is required. The grained and reversed negative having been made, such a mixture as the following is prepared for use in coating the plate to be etched (generally copper) : -
Commercial Liquid Fish Glue ...... 2 ozs.
White of Egg          ............ 2 ..
Water           ............... 4 ..
Ammonium Bichromate ...... ...      60 grs.
These materials are agitated together by shaking in a bottle containing some pieces of glass, and the mixture is filtered through cotton wool. A carefully cleaned and highly polished copper plate is now coated by flooding it with the mixture and pouring off the excess, and it is then dried in a horizontal position. Two or three minutes in sunlight is generally a suffi-cient exposure After exposure the plate is soaked in water to