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Guarbassi's Process 1867

The paper is floated in the dark for four or five minutes on a saturated
solution of bichromate of potash. When dry, it is printed a little longer
than for silver prints and afterwards floated, face upwards, on a water
bath until all the unaltered bichromate is dissolved. It is then immersed
in the following solution, which improve by use and tones the pictures to
a reddish color:

Saturated solution 4 parts
nitrate of mercury, as
free from acid as
Saturated solution 1 part
bichromate of potash
Distilled water 28 parts

This solution should be prepared, filtered and allowed to stand for some
time before use. The print is left in the bath until it has assumed an
intense red color, the whites remaining perfectly pure. It is then washed
and put in another bath to obtain a brownish tint. This bath is thus

Conc. aqueous ammonia 2 parts
Distilled water 100 parts

The print must be immersed at once, and when, in a short time, it has
assumed the proper color, it should be washed immediately.

The picture is toned in a very diluted solution of chloride of gold,
1:7,000, in which the color passes from a light brown to a deep black or a
violet black tone, when it is washed in two changes of water.

Next: A Poitevin's Process 1870

Previous: L Liesegang's Process 1865

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