Blueprint

Last updated December 03, 2024

Blueprint for a Butler-class destroyer escort, 1944

A blueprint is a reproduction of a technical drawing or engineering drawing using a contact print process on light-sensitive sheets introduced by Sir John Herschel in 1842.^[1] The process allowed rapid and accurate production of an unlimited number of copies. It was widely used for over a century for the reproduction of specification drawings used in construction and industry. Blueprints were characterized by white lines on a blue background, a negative of the original. Color or shades of grey could not be reproduced.

The blueprint process

The blueprint process is based on a photosensitive ferric compound. The best known is a process using ammonium ferric citrate and potassium ferricyanide.^[6]^[7] The paper is impregnated with a solution of ammonium ferric citrate and dried. When the paper is illuminated, a photoreaction turns the trivalent ferric iron into divalent ferrous iron. The image is then developed using a solution of potassium ferricyanide forming insoluble ferroferricyanide (Prussian blue or Turnbull's blue) with the divalent iron. Excess ammonium ferric citrate and potassium ferricyanide are then washed away.^[8] The process is also known as cyanotype.

This is a simple process for the reproduction of any light transmitting document. Engineers and architects drew their designs on cartridge paper; these were then traced on to tracing paper using India ink for reproduction whenever needed. The tracing paper drawing is placed on top of the sensitized paper, and both are clamped under glass, in a daylight exposure frame, which is similar to a picture frame. The frame is put out into daylight, requiring a minute or two under a bright sun, or about ten minutes under an overcast sky to complete the exposure. Where ultra-violet light is transmitted through the tracing paper, the light-sensitive coating converts to a stable blue or black dye. Where the India ink blocks the ultra-violet light the coating does not convert and remains soluble. The image can be seen forming. When a strong image is seen the frame is brought indoors to stop the process. The unconverted coating is washed away, and the paper is then dried. The result is a copy of the original image with the clear background area rendered dark blue and the image reproduced as a white line.

This process has several features:^[9]

the image is stable
as it is a contact process, no large-field optical system is required
the reproduced document will have the same scale as the original
the paper is soaked in liquid during processing, and minor distortions can occur
the dark blue background makes it difficult to alter, thus preserving
- the approved drawing during use
- a record of the approved specifications
- the history of alterations recorded on the sheet
- the references to other drawings

Introduction of the blueprint process eliminated the expense of photolithographic reproduction or of hand-tracing of original drawings. By the later 1890s in American architectural offices, a blueprint was one-tenth the cost of a hand-traced reproduction.^[10] The blueprint process is still used for special artistic and photographic effects, on paper and fabrics.^[11]^{[ self-published source? ]}

Various base materials have been used for blueprints. Paper was a common choice; for more durable prints linen was sometimes used, but with time, the linen prints would shrink slightly. To combat this problem, printing on imitation vellum and, later, polyester film (Mylar) was implemented.

Whiteprints

Traditional blueprints became obsolete when less expensive printing methods and digital displays became available.

In the early 1940s, cyanotype blueprint began to be supplanted by diazo prints, also known as whiteprints. This technique produces blue lines on a white background. The drawings are also called blue-lines or bluelines.^[12]^[13] Other comparable dye-based prints were known as blacklines. Diazo prints remained in use until they were replaced by xerographic print processes.

Xerography is standard copy machine technology using toner on copy paper. When large size xerography machines became available, c. 1975, they replaced the older printing methods. As computer-aided design techniques came into use, the designs were printed directly using a computer printer or plotter.

Digital

In most computer-aided design of parts to be machined, paper is avoided altogether, and the finished design is an image on the computer display. The computer-aided design program generates a computer numerical control sequence from the approved design. The sequence is a computer file which will control the operation of the machine tools used to make the part.

In the case of construction plans, such as road work or erecting a building, the supervising workers may view the "blueprints" directly on displays, rather than using printed paper sheets. These displays include mobile devices, such as smartphones or tablets.^[14] Software allows users to view and annotate electronic drawing files. Construction crews use software in the field to edit, share, and view blueprint documents in real-time.^[15]

Many of the original paper blueprints are archived since they are still in use. In many situations their conversion to digital form is prohibitively expensive. Most buildings and roads constructed before c. 1990 will only have paper blueprints, not digital. These originals have significant importance to the repair and alteration of constructions still in use, e.g. bridges, buildings, sewer systems, roads, railroads, etc., and sometimes in legal matters concerning the determination of, for example, property boundaries, or who owns or is responsible for a boundary wall.

Related Research Articles

Reprography is the reproduction of graphics through mechanical or electrical means, such as photography or xerography. Reprography is commonly used in catalogs and archives, as well as in the architectural, engineering, and construction industries.

Potassium ferricyanide is the chemical compound with the formula K₃[Fe(CN)₆]. This bright red salt contains the octahedrally coordinated [Fe(CN)₆]³⁻ ion. It is soluble in water and its solution shows some green-yellow fluorescence. It was discovered in 1822 by Leopold Gmelin.

The cyanotype is a slow-reacting, photographic printing formulation sensitive to a limited near ultraviolet and blue light spectrum, the range 300 nm to 400 nm known as UVA radiation. It produces a monochrome, blue coloured print on a range of supports, often used for art, and for reprography in the form of blueprints. For any purpose, the process usually uses two chemicals: ferric ammonium citrate or ferric ammonium oxalate, and potassium ferricyanide, and only water to develop and fix. Announced in 1842, it is still in use.

Xerography is a dry photocopying technique. Originally called electrophotography, it was renamed xerography—from the Greek roots ξηρόςxeros, meaning "dry" and -‍γραφία-‍graphia, meaning "writing"—to emphasize that unlike reproduction techniques then in use such as cyanotype, the process of xerography used no liquid chemicals.

Whiteprint describes a document reproduction produced by using the diazo chemical process. It is also known as the blue-line process since the result is blue lines on a white background. It is a contact printing process that accurately reproduces the original in size, but cannot reproduce continuous tones or colors. The light sensitivity of the chemicals used was known in the 1890s and several related printing processes were patented at that time. Whiteprinting replaced the blueprint process for reproducing architectural and engineering drawings because the process was simpler and involved fewer toxic chemicals. A blue-line print is not permanent and will fade if exposed to light for weeks or months, but a drawing print that lasts only a few months is sufficient for many purposes.

Sun printing may refer to various printing techniques which use sunlight as a developing or fixative agent.

In photography, toning is a method of altering the color of black-and-white photographs. In analog photography, it is a chemical process carried out on metal salt-based prints, such as silver prints, iron-based prints, or platinum or palladium prints. This darkroom process cannot be performed with a color photograph. The effects of this process can be emulated with software in digital photography. Sepia is considered a form of black-and-white or monochrome photography.

Gum printing is a way of making photographic reproductions without the use of silver halides. The process uses salts of dichromate in common with a number of other related processes such as sun printing.

Kallitype is a process for making photographic prints.

Chrysotype is a photographic process invented by John Herschel in 1842. Named from the Greek for "gold", it uses colloidal gold to record images on paper.

<span class="mw-page-title-main">Tracing paper</span> Paper made to have low opacity, allowing light to pass through

Tracing paper is paper made to have low opacity, allowing light to pass through. Its origins date back to at least the 1300s, when it was used by artists of the Italian Renaissance. In the 1880s, tracing paper was produced en masse, used by architects, design engineers, and artists. Tracing paper was key in creating drawings that could be copied precisely using the diazo copy process. It then found many other uses. The original use for drawing and tracing was largely superseded by technologies that do not require diazo copying or manual copying of drawings.

Ammonium ferric citrate has the formula [NH₄]y[Fex(C₆H₄O₇)]. The iron in this compound is trivalent. All three carboxyl groups and the central hydroxyl group of citric acid are deprotonated. A distinguishing feature of this compound is that it is very soluble in water, in contrast to ferric citrate which is not very soluble.

Canon Production Printing, known as Océ until the end of 2019, is a Netherlands-based subset of Canon that develops, manufactures and sells printing and copying hardware and related software. The product line includes office printing and copying machinery, production printers, and wide-format printers for both technical documentation and color display graphics.

Architectural reprography, the reprography of architectural drawings, covers a variety of technologies, media, and supports typically used to make multiple copies of original technical drawings and related records created by architects, landscape architects, engineers, surveyors, mapmakers and other professionals in building and engineering trades.

Potassium ferrioxalate, also called potassium trisoxalatoferrate or potassium tris(oxalato)ferrate(III) is a chemical compound with the formula K₃[Fe(C₂O₄)₃]. It often occurs as the trihydrate K₃[Fe(C₂O₄)₃]·3H₂O. Both are crystalline compounds, lime green in colour.

A photocopier is a machine that makes copies of documents and other visual images onto paper or plastic film quickly and cheaply. Most modern photocopiers use a technology called xerography, a dry process that uses electrostatic charges on a light-sensitive photoreceptor to first attract and then transfer toner particles onto paper in the form of an image. The toner is then fused onto the paper using heat, pressure, or a combination of both. Copiers can also use other technologies, such as inkjet, but xerography is standard for office copying.

A heliographic copier or heliographic duplicator is an apparatus used in the world of reprography for making contact prints on paper from original drawings made with that purpose on tracing paper, parchment paper or any other transparent or translucent material using different procedures. In general terms some type of heliographic copier is used for making: Hectographic prints, Ferrogallic prints, Gel-lithographs or Silver halide prints. All of them, until a certain size, can be achieved using a contact printer with an appropriate lamp but for big engineering and architectural plans, the heliographic copiers used with the cyanotype and the diazotype technologies, are of the roller type, which makes them completely different from contact printers.

A contact copier is a device used to copy an image by illuminating a film negative with the image in direct contact with a photosensitive surface. The more common processes are negative, where clear areas in the original produce an opaque or hardened photosensitive surface, but positive processes are available. The light source is usually an actinic bulb internal or external to the device

References

↑ Go., F. E. (1970). "Blueprint". Encyclopædia Britannica. Vol. 3 (Expo'70 ed.). Chicago: William Benton, Encyclopædia Britannica Inc. p. 816. ISBN 0-85229-135-3.
↑ Shorter Oxford English Dictionary (6th ed.), Oxford University Press, 2007, ISBN 978-0-19-920687-2
↑ "Blueprint". Dictionary.com. Retrieved February 6, 2016.
↑ "Blueprint". Merriam-Webster Dictionary. Retrieved February 6, 2016.
↑ C. Brown, Walter; K. Brown, Ryan (2011). Print Reading for Industry, 10th edition. The Goodheart-Wilcox Company, Inc. p. 4. ISBN 978-1-63126-051-3.
↑ Blue, WS: PSLC.
↑ C. Brown, Walter; K. Brown, Ryan (2011). Print Reading for Industry, 10th edition. The Goodheart-Wilcox Company, Inc. p. 7. ISBN 978-1-63126-051-3.
↑ Bridgwater, William; Sherwood, Elizabeth J., eds. (1950). "blueprint". The Columbia Encyclopedia in One Volume (hardbound) (Second ed.). Morningside Heights, New York City: Columbia University Press. p. 214.
↑ Ralph W. Liebing Architectural Working Drawings, John Wiley & Sons, 1999 ISBN 0471348767 page 576
↑ Mary N. Woods From Craft to Profession: The Practice of Architecture in Nineteenth-Century America University of California Press, 1999 ISBN 0520214943, pages 239–240
↑ Gary Fabbri, Malin Fabbri Blueprint to Cyanotypes – Exploring a Historical Alternative Photographic Process Lulu.com, 2006 ISBN 141169838X page 7^{[ self-published source ]}
↑ Pai, Damodar M.; Melnyk, Andrew R.; Weiss, David S.; Hann, Richard; Crooks, Walter; Pennington, Keith S.; Lee, Francis C.; Jaeger, C. Wayne; Titterington, Don R.; Lutz, Walter; Bräuninger, Arno; De Brabandere, Luc; Claes, Frans; De Keyzer, Rene; Janssens, Wilhelmus; Potts, Rod. "Imaging Technology, 2. Copying and Nonimpact Printing Processes". Ullmann's Encyclopedia of Industrial Chemistry . Weinheim: Wiley-VCH. pp. 1–53. doi:10.1002/14356007.o13_o08.pub2. ISBN 9783527306732.
↑ Blueprints replaced by whiteprints
↑ Singer, Michael. "Crain Construction grows its 80-year-old business with iOS, Android tablets". tabtimes.com. Archived from the original on 22 May 2014. Retrieved 21 May 2014.
↑ "Construction Blueprint App". HCSS. 15 December 2021. Retrieved 9 June 2022.

Blueprint

Contents

The blueprint process

Whiteprints

Digital

See also

Related Research Articles

References

Further reading