The difference between a cyanotype, blueprint and photogram
A blueprint looks very similar to a cyanotype, but was used more for technical drawings and plans.
For botanical studies, sheets of paper were treated with a light-sensitive product and placed in the sun with plants or other natural objects on top. The bright blue print left on the paper is called a photogram.
Old cyanotypes always have heritage value. You should therefore contact your local heritage society for more info about how to preserve, store and digitise your valuable find.
Did you know …
… the blueprint process originated as early as 1842, but is still used by photographers and artists today?