Page 41 - The Wellington photographic handbook

*

It is not an everyday occurrence that a negative requires
strengthening, but when the necessity does arise, with the above
stock solutions at hand it is only a matter of a very few minutes
to carry out the desired improvement. The work may be done
on the lines indicated with the certainty that the solutions used
have not deteriorated and without any risk of failure from staining.

THE CHROMIUM INTENSIFIED
This intensifier is simple in use and is a favourite with many
workers. Two solutions are required.
A.
Potassium bichromate ... ... ... ... 1 oz.
Water to ... ... ... ... ... ... 25 oz.
B.
Hydrochloric acid ... ... ... ... ... £ oz.
Water to ... ... ... ... ... ... 25 oz.
For use mix equal parts of A and B.
The negative is bleached in the mixture, washed until the yellow
bichromate stain has disappeared and is then darkened in a strong
developer containing no bromide. The amidol formula given on
page 67, with the bromide omitted, will be found very suitable. If
still more density is required the operation may be repeated.
After darkening the negative should be washed for ten minutes.

REDUCTION.
Negatives which are unduly dense may be reduced in what
:—
is known as Farmer's Reducer. This is made as follows
Potassium Ferricyanide ... 120 grains 7 grammes
Water to 20 ozs. 500 c.c.
A dram or two of this is added just before use to each ounce
of ordinary hypo solution. The negative is immersed in the reducer
until it is seen to be nearly sufficiently reduced in density and is
then well washed. Negatives that have been dried must be well
soaked before treatment. During the process of reduction the
dish must be steadily rocked.

* Before making up any formula, read the notes on pages 125, 126 and 134.
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