Spirit duplicator
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A spirit duplicator (also referred to as ditto machine or Banda machine) was a low-volume printing method used mainly by schools and churches, and by the science fiction community for the production of fanzines.
The term "spirit duplicator" comes from the old term for alcohols, which is "spirits." Alcohols were a major component of the solvents used as "inks" in these machines.
The spirit duplicator was invented in 1923 by Wilhelm Ritzerfeld.
The 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.
Ditto machines and mimeograph machines were always 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.
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 unflavored 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.
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. It should be noted that 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.
The thermofax machine was introduced by 3M in the late 1960s and could make a spirit master from an ordinary typewritten or handwritten sheet. The resulting print quality was abominable but the machines were still popular because of their convenience.
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.
Ironically, both the isopropanol and the methanol found in ditto solvents as well as the aniline, which produced the purple color most commonly used in spirit duplicators, are highly toxic substances. These chemicals can cause a host of medical problems. All three substances are suspected carcinogens (cancer-causing agents). Current Material Safety Data Sheet (MSDS) guidelines recommend the use of personal protective equipment during exposure to these chemicals, including gloves, goggles, and respirators.
Spirit duplicator technology fell into disuse with the availability of low-cost, high-volume xerographic copiers starting in the 1970s. Few spirit duplicators remained in use by 1985, although they remained popular through the early 1990s in applications such as use during events where no electrical power was available.
[edit] See also
[edit] 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)
