The Dictionary Of Photography

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

Home | About | Photography | Contact






Intensification
negatives should be removed now ; for normal work, the negative should be left in still longer, till it turns a lighter brown. No. VII. gives a bright reddish-brown negative. Whichever darkening solution is used, it should be allowed to act till the back of the image, as seen through the glass, is dark, and then thoroughly washed.
The Uranium Intensijier. This stains the image a bright reddish-brown. It is absolutely necessary that all hypo should be eliminated.
Potassium ferridcyanide(syn., ferricyanide)...        I part.
Uranium nitrate ... ... ... ...        I ..
Acetic acid, glacial ... ... ... ...       10 parts.
Water ..................     ioo ..
The plate, after intensification, should be well rinsed and dried ; continuous washing, especially in ordinary tap water, removes the intensification bodily. This very defect makes this process useful, as by means of an alkali any part of a negative intensified with uranium can be bleached by treatment with ammonium carbonate.
The Lead Intensijier. This gives a very dense increment, and is, therefore, rarely necessary or used.
Potassium ferridcyanide ... ... ...        6 parts.
Lead nitrate... ... ... ... ...        4 ,,
Acetic acid, glacial ... .........      10 ,,
Distilled water ...... ... ...     ioo ,,
Soak the negative in this solution till bleached, then wash thoroughly, and flood with ammonium sulphydrate ; then wash well and dry.
Silver Intensifies. Whilst some operators still hold to this, the relic of old wet-plate days, it has not found its way into general practice. It is difficult to avoid the occurrence of stains, as silver nitrate so readily combines with gelatine. Several formulae have been suggested.
A.
Pyrogallol ...............         I part.
Citric acid ...............        2 parts.
Distilled water ......... ...    300 ..
411