The Kallitype printing process (from the Greek word kalli meaning “elegant”, “beautiful”) is a member of the iron-based
photographic processes, which were first named and explained by Sir John Herschel in 1842. The Kallitype
was developed and patented in 1889 by Dr. W.W. J. Nicol.

The process starts when a high quality 100% cotton paper is coated with a mixture of ferric oxalate and
silver nitrate. Once the coating is dried,  a negative is  placed on top of it and exposed to sunlight or UV lamp.

During that exposure to UV light the ferric oxalate in the sensitizer reacts with the silver nitrate, changingthe silver metal salt into a partially realized metallic silver. This exposed kallitype is then processed in a developer, cleared and fixed. The prit can also be toned before fixing to achieve  long term archival properties.

The Kallitype is a process close to platinum/palladium in its reliance on ferric oxalate and a metallic
salt (platinum chloroplatinite or palladium chloride)to produce the image.