Reproduction of Documents

the process of making copies from the originals of various documents.

Reproduction is an important stage in the preparation of documents for designing, engineering, reference, information, and administration. The choice of method depends on the number of copies needed, the time needed to make the copies, the quality required, and the cost of reproduction. The most widely used methods are diazo copying, photocopying, electrographic copying, electronic copying, and thermocopying.

Diazo copying is one of the principal means of reproducing documents for engineering. It is economical and accessible and it presents practically no limitations on the format of the original. The use of diazo materials of varying sensitivities makes it possible to make copies of any transparent original. Diazo copying is relatively inexpensive, and the process, including developing, takes only a few minutes. The quality of the images depends primarily on the diazo materials used.

The highest-quality copies are made by photocopy. Although photographic materials are relatively expensive, photocopying remains the most widely used process for preparing copies and printing forms. The process of reflex photocopying, which can produce copies of practically any type of document, is in wide use. Because the apparatus used in photocopying is so versatile, suitable for making both single copies and printing forms, reproducing the necessary quantities by this method takes up a minimum of equipment space. Photoelectronic copying is used to make printing forms and single copies on paper, tracing paper, and special electrothermal paper from an original of any color and degree of contrast. The photoelectronic process is largely automated. Electrographic copying makes it possible to obtain high-quality single copies on ordinary paper and to make printing forms for offset.

Electronic copying is very widely used in preparing rotary stencils on plastic tapes. A most important property of the electronic copier is its ability to change the reproduction ratio with relative ease. Its reader and copier can be used separately, making it possible to transmit the image of a document by longdistance channels.

Thermo copying is one of the fastest reproduction methods. Within 3 to 10 seconds it is possible to obtain a copy of a sheet with textual, numerical, or graphic information. The copies are made on thermographic or plain paper. The quality of the copies obtained by thermocopying, however, is often poor, and the image lasts only a few months.

Documents are reproduced quickly for small and medium-sized runs by the devices used in the small graphic-arts and printing industries. The equipment used includes mimeographs for stencil printing, hectographs for spirit printing, and offset machines for planographic printing. The wide variety of copying equipment is a result of the diverse conditions of use and the differences in the kind of documents copied. The term “reprography” (the facsimile preparation of document copies) was proposed in the early 1950’s for reproduction processes.