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Columbia Encyclopedia entry: blueprint
Blueprint, white-on-blue photographic print, commonly of a working drawing used during building or manufacturing. The plan is first drawn to scale on a special paper or tracing cloth through which light can penetrate. The drawing is then placed over blueprint paper, prepared with a mixture of potassium ferricyanide and ammonium ferric citrate. When the attached drawing and the blueprint paper are exposed to a strong light, the unprotected ferric salt not lying beneath the lines of the drawing is changed to a ferrous salt that reacts with the ferricyanide to form Turnbull's blue. This blue is the background of the finished print. The ferric salt under the lines of the drawing, protected from the light, remains and is dissolved during the washing in water that follows exposure. As a result, the lines of the original drawing appear white in the finished blueprint.

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Wikipedia search results for: Blueprint
From Wikipedia, the free encyclopedia
A blueprint is a type of paper-based reproduction usually of a technical drawing, documenting an architecture or an engineering design. More generally, the term "blueprint" has come to be used to refer to any detailed plan. The blueprint process is essentially the cyanotype process developed by the British astronomer John Herschel in 1842. The photosensitive compound, a solution of ferric ammonium citrate and potassium ferricyanide, is coated onto paper. Areas of the compound exposed to strong light are converted to insoluble blue ferric ferrocyanide, or Prussian blue. The soluble chemicals are washed off with water leaving a light-stable print. A...more »
Columbia Encyclopedia search results: blueprint
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    Citric acid or 2-hydroxy-1,2,3-propanetricarboxylic acid, HO2CCH2C(OH)(CO2H)CH2CO2H, an organic carboxylic acid containing three carboxyl groups; it is a solid at room temperature, melts at 15...

  • photocopying

    Photocopying, process whereby written or printed matter is directly copied by photographic techniques. Generally, photocopying is practical when just a few copies of an original are needed. Wh...

  • gene

    Gene, the structural unit of inheritance in living organisms. A gene is, in essence, a segment of DNA that has a particular purpose, i.e., that codes for (contains the chemical information nec...

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    Sailing, as a sport, the art of navigating a sailboat for recreational or competitive purposes. There is no single yacht type of boat, rather many types that include sloops, yawls, catamarans,...

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