Give Us A Blue Print
Did you know?
The term blue print, derives from cyano type printing which was invented in the 1900s as a cheap form of photographic printing to be used by engineers. It proved so useful it went on to be used in all kinds of industries including the architectural and design industries.
The process of making cyanotype photographic paper was first invented by the English scientist and astronomer Sir John Herschel, who discovered the procedure in 1842 and used it primarily as a means of reproducing notes and diagrams, and so the term blueprint was coined.
Later Anna Atkins, the well renown early photographer and botanist used cyanotype printing to make exquisite images of fern leaves, which she published in a limited edition book. Atkins placed fern leaves and other plant specimens directly onto the surface of the coated and allowed the action of light to create a silhouette effect. The use of this photogram method and the publishing of her early book has earned Anna Atkins the title of first known female photographer.
Cyanotype photography was popular in Victorian England, but its popularity waned with improvements in photography. Today cyanotype papers are used widely for arts and crafts activities resulting in some stunning art pieces. It can also be used for non quantitative science experiments with children to assess the efficacy of sun blocking skin lotions.
How Cyanotype Paper Is Made
Cyanotype paper is relatively easy, if a little messy and slow to make. Solutions of potassium ferricyanide and ferric ammonium citrate are mixed together. The depth of reaction to sunlight can be enhanced by the addition of a sensitizer chemical called potassium dichromate.
This photosensitive solution is then applied to a paper surface and allowed to dry in a dark place.
It is the Ultraviolet rays in sunlight that cause the photographic image to be formed after the paper has been exposed to light. The UV light in the presence of the citrate reduces the Iron III to Iron II, this is then followed by a complex reaction between the Iron II and the ferricyanide. The end result of this chemical reaction is the synthesis of an insoluble, blue pigment, ferric ferrocyanide, commonly known as Prussian blue.
The length of exposure time needed to catalyse the reaction vary widely, from a few seconds in strong direct sunlight, to 10–20 minute exposures on a dull day. The reaction will not work successfully using artificial lighting where UV light is absent.
After exposure to sunlight, the sun print (cyanotype) paper is then developed (fixed) by washing the paper in cold running water to wash away the water-soluble iron(III) salts are leaving the insoluble Prussian blue pigment behind on the paper giving the very typical images of strong blue background with white silhouette of the objects such as plant leaves. As the paper dries, the blue colour will deepen and darken.
Ta Dah! We've taken The Hassle Out Of It With Our Sun Print Paper!
Our sun print paper is a simple form of photographic paper that is great fun and can be used to make some stunning 'sun art' using hands, feet, leaves, flowers, shells or any other object you choose. The object or objects are placed on the photo-sensitive paper and left in place in the sun for a few minutes. Remove the objects and rinse the paper in water to 'fix' it. You can admire your beautiful sun art! Each pack contains 10 x sheets 18x13cm of light sensitive sun print paper.