Page 74 - The Wellington photographic handbook

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THE SULPHIDE PROCESS.
Prints for toning by the Sulphide process should be correctly
exposed and allowed to remain in the developer until the action
of the solution is seen to stop, which, with the formulae previously
given, will occur in about two minutes. Prints which have been
over-exposed and then developed for a brief period will often
appear fairly satisfactory in the black and white stage, but will give
an unpleasant yellow tone in the sulphide bath.
Fixing and washing must be thorough. Imperfect fixing will
result in the appearance of dark stains after immersion in the
sulphide bath, and imperfect washing will give rise to patches
which refuse to darken in the sulphide, but remain a pale yellow
colour.
The following stock solutions are required for toning*
No. l.
Potassium Ferricyanide ... 400 grains 45 grammes
Potassium Bromide ... ... 600 ; , 65
Water to 10 ounces 500 c.c.
This solution keeps almost indefinitely if protected from the action of light.
No. 2.
Sodium Sulphide (pure) ... 1 ounce 30 grammes
Water to 10 ounces 300 c.c.
This solution will keep for a few months only.
To tone the print it is immersed in
Stock solution of Ferricyanide
and Bromide 1 ounce 50 c.c.
Water to 10 ounces 500 c.c.
In this the image will almost disappear in something under
five minutes. The print should be left in the solution until there
is no doubt that the action has gone as far as it will, and must then,
after a wash of about five minutes, be immersed in
Stock solution of Sodium Sulphide | ounce 25 c.c.
Water to 10 ounces 500 c.c.
In this the print gradually re-develops to a fine sepia colour.
It should be left until there is no doubt that the action of the
solution is complete, after which it should be washed in several
changes, or in running water for a quarter of an hour.
* Bejore making up any formula, read the notes on pages 125, 126 and 134.
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