What is the Cyanotype Process?

The Cyanotype process, originally created by Sir John Herschel in 1842, is also known as a "blueprint" process. The final print is characteristically blue in color. The print is typically has a short-scale tonal range, making it somewhat "contrasty." The cyanotype print is also known as a "non-silver" process, since it employs ferric (iron) salts for its photosensitivity, from a combination of two solutions, one containing ferric ammonium citrate and the other solution containing potassium ferricyanide. Combining these complete solutions in equal parts creates a sensitizing solution which is then brushed or painted onto the surface of a substrate like cloth or hot-press watercolor paper.

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