The Dictionary Of Photography

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

Home | About | Photography | Contact

A. Pyrogallol Developer.
Solution of pyro (7 per cent.) ......        2 parts.
.. .. sodium acetate (20 per cent.)          6 ,,
Distilled water         ............      60 M
B. Paramidophenol Developer.
Solution of paramidophenol (7 per cent.)           2 parts.
.. ,, sodium acetate (20 per cent.)         10 ..
Citric acid ... ...... ... ... 1 ..
Distilled water ...... ... ...      50 ..
Substantial advance in this process was made by Mr. Wilson, of the Paget Prize Plate Co., when he suggested the use of a solution of potassium bromide prior to development. The follow-ing is the precise method of working this modification of the process : - The paper should be exposed in the printing frame in the ordinary way, but the insolation is only continued till there is quite a faint image. It is advisable not to print too far, and as a good guide we may suggest that the details should just be visible in the half-tones. After printing, the paper should be taken from the frame, and placed without washing into a 10 per cent, solution of potassium bromide. The action of this bath is to convert the soluble silver salts into silver bromide, and if allowed to act for some time, there is no doubt it would also replace the chlorine in the silver salt forming the image. The time of immersion in the bromide solution is not very material, and we prefer to leave it for fifteen minutes. Great care must be taken that no bubbles adhere to the paper, or else spots will appear in the development. After being in the bromising solu-tion the prints must be washed well for five or ten minutes in running water; if the washing is not pretty complete and thorough, so much bromide is left in the paper that development is enor-mously protracted, and there is a tendency to stain. The original developer recommended was -