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When was blueprinting invented?
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Figure 1: Two techniques of representing an object. (A) Perspective drawing, suggesting that the object is cubical. (B) Orthographic top and front views, revealing that the object is not cubical.
Blueprinting was invented in 1842 by the astronomer and chemist Sir John Herschel.12
The process, originally known as the cyanotype process, utilizes paper sensitized with a mixture of ferric ammonium citrate and potassium ferricyanide. When exposed to light, the uncovered areas of the paper turn a deep blue, while the lines of a drawingâplaced on translucent materialâremain white. This method became the first economical way to duplicate engineering and architectural drawings, eventually being introduced in the United States in 1876.312