Blueprint
From Free net encyclopedia
- For the 2003 film of the same title, see Blueprint (film).
A blueprint is, conceptually, a plan or design documenting an architecture or an engineering design. While this may be as simple as a quick sketch or outline using pencil and paper, a blueprint is traditionally reflected as the contact printing process of cyanotype. It is cyanotype which produces the familiar white lines on blue background. The term is often used metaphorically to mean any detailed plan.
Invention
The blueprint process was developed by the British astronomer Sir John Herschel in 1840. The photosensitive compound, a solution of ammonium ferric 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 similar process was used to produce printing proofs for offset printing.
Replacements for blueprints
Blueprints have mostly been replaced by Diazo prints or whiteprints, which have blue lines on a white background; thus these drawings are called blue-lines or bluelines. These are sometimes also known, incorrectly, as blueprints. Other comparable prints are known as Blacklines.
Revision control was done in contrasting color on the blueprints, for example red markup of a blueprint copy by the engineer, then yellow markup on the copy by the draftsman who implemented the changes on the original drawing, then brown markup by the checker, on a check-print (a brown-line) or Sepias. Finally, the architect or engineer, draftsman, checker and supervisor would sign the original drawing, thus making it a legal document.
Diazo prints have been replaced by a digital process using toner on bond paper, files are electronically introduced or scanned in.
In the past, linen was also used to produce blueprints, but with time, the prints would shrink slightly. To combat this problem, printing on mylar was implemented.de:Blaupause id:Cetak biru nl:Blauwdruk