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.