codzienność: Cyanotype

Evidence: 100 • authority: 72

The cyanotype (from Ancient Greek: κυάνεος, kyáneos 'dark blue' and τύπος, týpos 'mark, impression, type') is a slow-reacting, photographic printing formulation sensitive to a limited near-ultraviolet and blue light spectrum, the range of 300 nm to 400 nm, known as UVA radiation. It produces a monochrome, blue-coloured print on a range of supports, and is often used for art and reprography in the form of blueprints. For any purpose, the process usually uses two chemicals – ferric ammonium citrate or ferric ammonium oxalate, and potassium ferricyanide, and only water to develop and fix. Announced in 1842, it is still in use.

Evidence: 43 • authority: 72

Ammonium ferric citrate (also known as ferric ammonium citrate or ammoniacal ferrous citrate) has the formula [NH4]{y}[Fe{x}(C6H4O7)]. The iron in this compound is trivalent. All three carboxyl groups and the central hydroxyl group of citric acid are deprotonated. A distinguishing feature of this compound is that it is very soluble in water, in contrast to ferric citrate which is not very soluble. In its crystal structure each moiety of citric acid has lost four protons. The deprotonated hydroxyl group and two of the carboxylate groups ligate to the ferric center, while the third carboxylate group coordinates with the ammonium.

Evidence: 37 • authority: 72

A heliographic copier or heliographic duplicator is an apparatus used in the world of reprography for making contact prints on paper from original drawings made with that purpose on tracing paper, parchment paper or any other transparent or translucent material using different procedures. In general terms some type of heliographic copier is used for making: Hectographic prints, Ferrogallic prints, Gel-lithographs or Silver halide prints. All of them, until a certain size, can be achieved using a contact printer with an appropriate lamp (ultraviolet, etc...) but for big engineering and architectural plans, the heliographic copiers used with the cyanotype and the diazotype technologies, are o…

Evidence: — • authority: 72

The history of photography began with the discovery of two critical principles: The first is camera obscura image projection; the second is the discovery that some substances are visibly altered by exposure to light. There are no artifacts or descriptions that indicate any attempt to capture images with light sensitive materials prior to the 18th century. Around 1718, Johann Heinrich Schulze used a light-sensitive slurry to capture images of cut-out letters on a bottle. However, he did not pursue making these results permanent. Around 1800, Thomas Wedgwood made the first reliably documented, although unsuccessful attempt at capturing camera images in permanent form. His experiments did prod…