Loo Roll – Idea 3

Rather than taking a photo of Loo Roll, I could use Loo Roll in my printing process. While writing my essay I came across William Henry Fox Talbot, which introduced me to Calotype which is a Photographic Process introduced in 1841 which used Paper coated with Silver Iodide, which when exposed to light, darkened. Then through browsing the internet to see whether this was do-able. I remember Cyanotypes from back in A-levels.

Cyanotype is again a Photographic process, but rather than using Silver Iodide, it uses two chemicals; Ammonium Iron(III) Citrate and Potassium Ferricyanide.

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To create the mix, equal volumes of both chemicals are mixed to create a mildly photosensitive solution. This is then applied to a surface such as paper or cloth and set to dry in a dark place. Cyanotypes can be printed onto any surface capable of soaking up the Iron solution.

A positive image can be produced by exposing it to a source of UV light (such as sunlight or UV light bulbs) as a contact print through negative or objects. The combination of UV light and the Citrate reduces the Iron(III) to Iron(II).  The result is a insoluble blue dye called Prussian Blue. The extent of the colour depends on the amount of UV light, but acceptable results are usually obtained after 10/20mins exposure on a dark, gloomy day.

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