technological drawings of architectural or technology purpose always seem to consist of white images and text edition on blue paper . Why ?
It ’s because of how those documents are made . The blueprinting process was developed in the mid-1800s , when scientist reveal thatammonium atomic number 26 citrateandpotassium ferrocyanidecreated a light-sensitive solution that could be used for reproducing documents .
The mental process goes like this : Someone creates a drawing on semitransparent trace paper or cloth . The drawing is placed over a piece of blueprinting paper , which has been cake with a commixture of ammonium ion iron citrate and potassium ferrocyanide from an aqueous result and dried . When the two newspaper publisher are exposed to a bright luminosity , the two chemicals react to work an indissoluble blue compound call blue ferrous ferrocyanide ( also known as Prussian Blue),exceptwhere the blueprinting paper was hide , and the light block , by the personal line of credit of the original drafting . After the paper is washed and dry out to keep those line of work from exposing , you ’re left with a negative look-alike of white ( or whatever color the blueprint paper originally was ) against a benighted downhearted background .
The technique was faster and more toll - in force than hand - hunt original document , and capture on as an easy , inexpensive means to procreate drawings and texts . After carbon copy copying and copier machines took on that line for smaller text file , architects , engineers and ship builder continued to apply blueprinting to copy their large - musical scale drawings . More recently , the diazo whiteprint process and bombastic - format xerographic photocopier have largely replaced blueprinting even for these specialized purposes , and many “ blueprints ” are now black-market or grey lines on a white background . Xerograph just does n’t have the same halo asblueprintfor a stenography verbal description for a master plan , though .
