The Dictionary Of Photography

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

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Development and Developers
avoided, as with these plates or films a considerable amount of over-exposure can be controlled in development, but if the light has not acted sufficiently on the plate no process of development can possibly make a good negative of it. For interiors and other subjects possessing great contrasts of light and shade, a weak developer should always be used. One of the best and most efficient methods of correcting over-exposure is that introduced by Mr. Edwards in 1888. This consists in using a separate strong but well-restrained developer as a redeveloper, which is substituted for the normal developer, as soon as over-exposure is recognised. When developing this redeveloper is kept ready mixed in a measure, and if the detail of the negative rushes up too quickly, indicating over-exposure, the normal developer is poured off and the redeveloper instantly substituted for it without waiting to wash the plate ; by this means very considerable over-exposure can be satisfactorily remedied, the redeveloper giving density without bringing out much more detail. This method of tentative development will be found exceedingly useful when developing a number of various or unknown exposures. The following is the formula for pyro. and ammonia redeveloper; separate formulae are given for redevelopers to be used with pyrb and soda, and hydrokinone or eikonogen : -
Pyro and Ammonia Redeveloper. No. 1.
Pyro ... ... ... ... ... ... 1 oz.
Citric acid         ...        ...        ...        ...        ... 2 drs.
Distilled water... ... ... ... ... 32 ozs.
No. 2.
Ammonia (*88o)          ...        ...        ... ... 2 ozs.
Bromide of ammonia ...        ... ...        ... 24 drs.
Distilled water... ... ... ... ... 32 ozs.
For use mix equal parts of Nos. 1 and 2.
Pyro and Soda Redeveloper. No. 1. Pyro .................. 1 oz.
Metabisulphite of soda (Boake's) ...        ...        1 ..
Distilled water...        ...        ...        ...        ... 28 ozs.
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