Page 40 - The Wellington photographic handbook

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Too long an immersion in this bath causes the image to
bleach, which should be avoided if it is desired to retain the
original gradation. In the time prescribed there is no apparent
change, but the clearing agent has done its work.
The negative
should now be rinsed for a few minutes and then intensified in
the following :
STOCK SOLUTIONS.
A.
Silver Nitrate 800 grains 91-2 grammes
Distilled water to 20 ounces 1 litre
B.
Ammonium Sulphocyanide ... 1400 grains 160 grammes
Hypo 1400 „ 160
Water to 20 ounces 1 litre
(Both solutions keep indefinitely.)
Half an ounce of A should be taken and added to half an
ounce of B, stirring vigorously with a glass rod. The solution
should be quite clear ; if the stirring is omitted it is apt to be
turbid. To this solution should be added 1 dram of a 10 per cent,
solution of Pyro preserved with Sulphite, and 2 drams of a 10 per
cent, solution of Ammonia. The negative should be placed in a
In a
chemically clean dish and the silver solution poured over it.
minute or two the deposition of the silver begins to take place,
and as soon as sufficient density has been acquired the negative
should be placed in an acid fixing bath until the slight pyro stain
is removed. After this bath the negative should be well washed
;
during washing it is as well to rub the surface of the film with a
tuft of cotton wool to remove the slight surface deposit which will
be found upon it.
It is important that the negative to be intensified should
have been thoroughly fixed in a clean fresh hypo bath, and not
merely have been left for some indefinite period in a stale or dirty
solution of hypo that has been used on other occasions.

It the original negative is flat from over-exposure, greater
contrast may be obtained by over-intensification and subsequent
reduction with Farmer's reducer (see next page).
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