Updated: Jan 20, 2022
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FINAL IMAGE AFTER SEPIA TONING PROCESS
The sepia toning is a procedure of ancient photography: in addition to making a very characteristic image, it is used to stop the oxidation of silver with the sulphurization method; this allows the image to last much longer; practically, metallic silver, instead of combining with the oxygen in the air, combines with sulfur. The procedure consists of two successive baths:
It bleaches it, which prepares for the next bath (it is similar to Farmer's weakener, but much more concentrated);
The sulphurisation, with which the sulfur is fixed to the metallic silver, giving a brownish-brown tone.
Changing the proportions of the ingredients produces more or less pronounced effects.