What is cyanotype?
Cyanotype is an early photographic process that continues to be popular with fine artists today. The process works by treating paper with iron salts that react with light to create a Prussian Blue color. The process is especially valued for its ability to pick up a great amount of detail in the resulting print. You can see the veins in the leaves of Anna Atkins' print, for example.
So the prints are always blue?
Yes! The process can only produce shades of blue.