Frequently Asked Questions
What is a siderotype?
A photographic method of printing images or text utilising light sensitive iron salts in combination with salts of gold, platinum, palladium, silver, or a number of other elements. Siderotypes based on gold and platinum are the most permanent photographic prints presently made.
The complete list of currently known siderotypes is as follows: amphitype, argentotype, argyrotype, aurotype, breath print, brown line, chromatic photo, chrysotype, cyanotype, ferrogallic process, haemotype, kallitype, kelaenotype, Nakahara's process, palladiotype, pellet print, Phipson's process, platinotype, printout platinum, satista print, sepia platinotype, sepiatype and vandyke.
What colour are siderotype prints?
Siderotypes range in colour: platinotype offers a deep black; chrysotype ranges from muted grey/black to blue, green, violet, red and pink; cyanotype is traditionally light/medium blue, but can be manipulated to produce deep blue or yellow; palladiotype is a deep brown.
How is a siderotype made?
All siderotype prints are contact printed and wet-processed. A silver or digital negative with the correct density is created; a piece of paper (ideally 100% cellulose) is coated with a sensitiser composed of gold, platinum, silver or other material and then dried; the negative is contact printed onto the paper using ultraviolet light; the paper is variously given humidity or chemical baths and then washed in water to remove everything but the metal or pigment constituting the image. The entire process takes from two to three days to produce a finished print.