Today blueprints are becoming widely digitized; architects are switching to computer rendering software. Prior to this, blueprints came from a process created in 1842 known as the cyanotype. Architects would create the original drawing on a semitransparent paper, then place it on a paper or cloth coated in photosensitive material which responds to light. The two items would then be exposed to light, creating a blueprint or a copy. The lines drawn on the original would block the light when exposed and this left white lines on a blue background. Invented by John Herschel, the cyanotype process gave architects inexpensive and efficient copies of their original architectural drawings.
The blueprint process has gone through several changes, such as aniline prints, diazotype, hectographs, and many others. The diazo process may be the most recognizable, as it took the place of the cyanotype for much of the 20th century. Diazotypes would create the reverse effect of a cyanotype and instead have blue lines on a white background, commonly called a “blue line”. These thin, small blue lines have helped create big parts of our world.
The evolution of blueprints parallels the evolution of architectural design stages in this exhibit. The design process is continually building and changing on itself.