Ultraviolet (UV)
Ultraviolet (UV) light drives the chemical reaction that makes cyanotype printing possible.
The cyanotype solution contains light-sensitive iron salts, primarily ferric ammonium citrate and potassium ferricyanide. When UV light strikes the coated surface, photons from the light provide the energy needed to reduce ferric iron (Fe³⁺) into ferrous iron (Fe²⁺). This reduction only occurs in the areas exposed to sufficient UV radiation (Light), meaning the intensity and duration of UV exposure directly control how much of the reaction takes place.
The newly formed ferrous iron then reacts with ferricyanide ions to produce insoluble iron compounds that later oxidize into Prussian blue pigment.
Areas receiving stronger or longer UV exposure create more of this pigment, resulting in darker blue tones. Regions shielded from UV light do not undergo the reaction and therefore remain uncolored after rinsing.
In essence, UV light acts as the activating energy source that selectively converts the light-sensitive coating into the permanent blue image.
STUDIO WETWARE 