Duplicating machines
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[edit] Mechanical Duplicators
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 They have now been replaced by Digital Duplicators, scanners, laser printers and photocopiers, but for many years they were the primary means of reproducing documents for mass distribution.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. The second phase of the industrial revolution is also called the Second Industrial Revolution. 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.
Self-publishers used these machines to produce fanzines, and they were also much used in schools, where cheap copying was in demand for the production of newsletters and worksheets.
stencil duplicator
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. You 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 you put the stencil on the drum wrong-side-out, your 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 wax that had been impregnated with one of a variety of colorants. 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 ditto masters were also manufactured in red, green, blue, black, and the hard-to-find orange, yellow, and brown. All except black reproduced in pastel shades: pink, mint, sky blue, etc. Ditto had the useful ability to print multiple colors in a single pass, which made it popular with cartoonists. Multi-colored designs could be made by swapping out the waxed second sheets; for instance, shading in only the red portion of an illustration while the top sheet was positioned over a red-waxed second sheet. This was possible because the pungent-smelling duplicating fluid (typically a 50/50 mix of isopropanol and methanol) was not ink, but a clear solvent.
There is no ink used in spirit duplication. As the paper moved through the printer, the solvent would be spread across each sheet by an absorbent wick. When the solvent-impregnated paper came into contact with the waxed original, it would dissolve just enough of the pigmented wax to print the image onto the sheet as it went under the printing drum.
This process worked best with cheap, lightweight paper stocks, but when the sheets of paper were impregnated with the solvent they could easily crease or crumple, jamming the machine. One well-made ditto master could at most print about 500 copies--far fewer than a mimeo stencil could manage--before the pigment was exhausted and the print quality became unreadably faint. If fewer copies were required, the master could be removed from the printing drum and saved for future use.
The aroma of pages fresh off the Ditto machine was a memorable feature of school life for those who attended in the ditto machine era. A pop culture reference to this is to be found in the film Fast Times At Ridgemont High. At one point a teacher hands out a dittoed exam paper and every student in the class immediately lifts it to his or her nose and inhales.
[edit] 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 dose 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. 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 1000 prints the master cost per copy is only .0004-.0008 cents per copy.
Other manufacturers have adapted the technology including.
[edit] 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.
- 1. The original is placed on a flat bed scanner or feed through a sheet feed scanner depending on the model.
- 2. When the start button is pressed the image is scanned into memory by reflecting light off the orignal and into a CCD.
- 3. 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.
- 4. As the new master is burning it is stored while the old master is removed.
- 5. 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.
- 6. The new master is fed into the clamp which closes, the drum is turned pulling the master onto the drum.
- 7. The outside of the drum is covered in screens and the inside is coated in ink. The screens make sure the ink is regulated.
- 8. The paper is fed to the drum and the ink only comes through the master material where there are holes.
- 9. A pressure roller presses the paper to the drum and transfers the ink to the paper to form the image.
- 10. The paper then exits the machine into a exit tray. The ink is still wet.
A master is capible of making 4000-5000 prints.
[edit] See also
- List of duplicating processes
- hectograph
- thermofax machine
- Cyclostyle
- Duplicator
- Gestetner
[edit] External links
- "Duplicating in the year B.C. - Before (xerographic) Copies"
- Repeat-O-Type Corporation still sells supplies (ink, stencils, etc.) for mimeograph and ditto machines.
