File:The American annual of photography (1912) (14762723441).jpg

Identifier: americanannualof1912newy (find matches)
Title: The American annual of photography
Year: 1912 (1910s)
Authors:
Subjects: Photography
Publisher: New York : Tennant and Ward
Contributing Library: Harold B. Lee Library
Digitizing Sponsor: Brigham Young University

View Book Page: Book Viewer
About This Book: Catalog Entry
View All Images: All Images From Book
Click here to view book online to see this illustration in context in a browseable online version of this book.

Text Appearing Before Image:
the fact of being able tomake a carbon picture from an enlarged bromide print, orto reproduce a permanent picture in any monochrome from aquestionable lasting bromide print, would have induced manyworkers in America to endeavor to overcome inevitable initialdifficulties. But not since bromide printing has become athoroughly practical method has any new printing process beenintroduced, except ozotype and ozobrome, and it is withoutdoubt the newness of the process and the inability to turn toa friend for advice when in difficulty that has limited itsadoption in America. In England there are many very en-thusiastic ozobrome workers who find the work much moresimple and convenient than carbon printing. The principle and method of working are simple. A sheetof pigment plaster or paper coated with pigmented gelatineis first soaked in the diluted ozobrome pigmenting solutionand then immersed for a few seconds in an acid bath. Theplaster after this treatment is then squeezed to a bromide 192
Text Appearing After Image:
A WINTER MORNING. CHAS. K. ARCHER. print and the act of bleaching, in the presence of the acid,causes the gelatine in contact with the silver image to becomemore or less insoluble in exact proportion to the deposit ofsilver. Now the quantity of acid present determines the de-gree of insolubility. It is a case of oxidation of the productof bleaching. A small quantity of acid will tan the gelatineonly moderately, and then we get strong color and swollengelatine in the shadows and possibly insufficiently tannedgelatine in the high lights, causing the picture to present harshcontrasts. It may seem strange that a heavier picture isobtained by a limited degree of tanning and this requiresexplanation. The ozobrome solution simply bleaches the imageand the acid reoxidizes the product resulting from the bleach-ing action, and thus the tanning effect is produced. If a small quantity of acid is present the insolubilizing actionbeing weak will proceed a comparatively long way through thegelatine

Note About Images