|The kallitype is, like cyanotype, platinum and palladium, a printing process based on the light sensitivity of ferric iron salts. Here the reduced iron compound is used to form an image made of silver.
Kallitype was known as 'the poor man's platinum' and can be used to produce images impossible to distinguish visibly from platinum prints at a small fraction of the cost. Kallitypes can also be gold or platinum toned, which can also make them difficult to distinguish from platinum prints. ||
One mistake often made in processing kallitypes is to use normal fixers; kallitypes do not generally require fixing, and a short immersion in very dilute neutral sodium thiosulphate solution is adequate.
There are many variations to the basic iron/silver kallitype process.
The water-developing kallitype is
sometimes known as a van dyke or sepia print. Traditional kallitypes use a ferric oxalate based sensitiser and require the use of a suitable developer.