Duplicating machines
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Duplicating machines were the predecessors of modern document-reproduction technology. They have now been replaced by digital duplicators, scanners, laser printers and photocopiers, but for many years they were the primary means of reproducing documents for mass distribution.
Like the typewriter, these machines were children of the second phase of the industrial revolution which started near the end of the 19th century (also called the Second Industrial Revolution)[citation needed][jargon]. This second phase brought to mass markets things like the small electric motors and the products of industrial chemistry without which the duplicating machines would not have been economical. By bringing greatly increased quantities of paperwork to life the duplicating machine and the typewriter gradually changed the forms of the office desk and transformed the nature of office work.
They were much used in schools, where cheap copying was in demand for the production of newsletters and worksheets, and self-publishers used these machines to produce fanzines.
Contents
Mechanical duplicators
The mimeo machine (mimeograph) used heavy waxed-paper "stencils" that the typewriter cut through. The stencil was wrapped around the drum of the (manual or electrical) machine, which forced ink out through the cut marks on the stencil. The paper had a surface texture (like bond paper), and the ink was black and odourless. A person could use special knives to cut stencils by hand, but handwriting was impractical, because any loop would cut a hole and thus print a black blob. If the user put the stencil on the drum wrong-side-out, the copies came out mirror-images.
The ditto machine (spirit duplicator) used two-ply "spirit masters" or "ditto masters". The first sheet could be typed, drawn, or written upon. The second sheet was coated with a layer of colored wax. The pressure of writing or typing on the top sheet transferred colored wax to its back side, producing a mirror image of the desired marks. (This acted like a reverse of carbon paper.) The two sheets were then separated, and the first sheet was fastened onto the drum of the (manual or electrical) machine, with the waxed side out.
The usual wax color was aniline purple, a cheap, durable pigment that provided good contrast, but other colors were available. Unlike mimeo, ditto had the useful ability to print multiple colors in a single pass, which made it popular with cartoonists. One well-made ditto master could at most print about 500 copies—far fewer than a mimeo stencil could manage.
The hectograph was an earlier technology in which a dye-impregnated master copy, not unlike a ditto master, was laid on top of a cake pan full of firm gelatin. After the dye soaked into the gelatin, sheets of paper could be laid on top of the gelatin to transfer the image. This was good for fifty copies at most. Hectography was slow, clunky, and weird, but it could inspire great intrepidity in its users.
Ditto machines and mimeograph machines were competing technologies. Mimeography was in general a more forgiving technology. Ditto machines required much finer operating tolerances and careful adjustments to operate correctly. Overall print quality was frequently poor, though a capable operator could overcome this with careful adjustment of feed rate, pressure, and solvent volume.
During their heyday, tabletop duplicators of both sorts were the inexpensive and convenient alternative to conventional typesetting and offset or letterpress printing. They were well suited for the short runs used for school worksheets, church newsletters, and apazines. Even the least technically-minded teachers, professors, and clergy could make use of them. They owed most of their popularity to this relative ease of use—and, in some cases, to their lack of a requirement for an external power source.
Mimeograph machines predated the spirit duplicator, had a lower cost per impression, superior print quality, finer resolution, and if properly adjusted could be used for multi-pass printing. Also, mimeographed pages didn't bleach white if exposed to sunlight, the way that dittoed pages did. As with ditto masters, mimeo stencils could be saved and reused for later print jobs. Mimeograph had a largely unwarranted reputation for being messier than spirit duplication. In truth, they weren't significantly messier; and if spilled mimeo ink was hard to get out of the operator's clothing, ditto's aniline purple dye was well-nigh impossible.
The perception may have been a side effect of their engineering. Mimeography, with its loose tolerances, absence of noxious solvents, and consequent open architecture (which put its inky pads and rollers on display), may simply have looked messier, and hence seemed more daunting. Spirit duplicators, whose demanding tolerances and constant fog of solvent fumes necessitated precisely machined metal parts and closed architecture, tended to have a deceptively clean and simple look. There are still diehard mimeography enthusiasts in the United States and Canada, and that mimeo technology is still in everyday use in the Third World.
Digital duplicators
In 1986 the RISO Kagaku Corporation introduced the Digital duplicator. It uses the duplicator technology but improves on it.
It improves upon the mimeo machine in that the operator does not have to create the stencil. The stencil, called a master is made by use of a scanner and thermal print head. Also the master is automatically removed as a new one is created and placed in a disposal box. This way the operator should not have to touch the used master material that is coated in ink.
There are also cost advantages over a copier the higher the volume. For smaller print runs the main cost is in the master material. This ranges between 40 – 80 cents per master depending on the manufacturer. When spread over 20 or more copies the cost per copy (2 to 4 cents) is close to photocopiers. But for every copy the costs decrease. At 100 prints the master cost per copy is only .4–.8 cents per copy, and the cost of the paper printed upon will start to dominate.
Other manufacturers have adapted the technology including:
How digital duplicators work
Like the mimeo machine, digital duplicators have a stencil (called a master), ink, and drum—but the process is all automated.
- The original is placed on a flat bed scanner or feed through a sheet feed scanner depending on the model.
- When the start button is pressed the image is scanned into memory by reflecting light off the original and into a CCD.
- The image is burned onto the master material that is coated on one side, in a series of small holes by the thermal print head.
- As the new master is burning it is stored while the old master is removed.
- There is a clamp plate on the drum that opens by motor. The drum turns and the old master material is feed into the disposal rollers and into the disposal box.
- The new master is fed into the clamp which closes, the drum is turned pulling the master onto the drum.
- The outside of the drum is covered in screens and the inside is coated in ink. The screens make sure the ink is regulated.
- The paper is fed to the drum and the ink only comes through the master material where there are holes.
- A pressure roller presses the paper to the drum and transfers the ink to the paper to form the image.
- The paper then exits the machine into an exit tray. The ink is still wet.
A master is capable of making 4000–5000 prints.
See also
References
- The Dead Media Project
- M P Doss, Information Processing Equipment (New York, 1955)
- Irvin A. Herrmann, Manual of Office Reproduction (New York, 1956)
- W B Proudfoot, The Origin of Stencil Duplicating (London, 1972)
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