Spirit duplicator
Encyclopedia
A spirit duplicator was a low-volume printing method used mainly by schools and churches. It was also used by members of science fiction fandom
and early comic book fandom to produce fanzines. Sheets printed on such a machine were sometimes called ditto sheets, or just dittos in the U. S. (an example of a genericized trademark
). The term "spirit duplicator" refers to the alcohols which were a major component of the solvents used as "inks" in these machines. They are sometimes confused with the mimeograph, which is actually a different technology.
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 very poor but the machines were popular because of their convenience.
Spirit duplicator technology gradually fell into disuse starting in the 1970s after the availability of low-cost, high-volume xerographic copiers
; by the mid 1990s, the use of the technology was rare. The technology remains useful where electrical power is unavailable or where the only remaining originals of legacy documents requiring duplication are in "spirit master" form.
.) 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.
There is no ink used in spirit duplication. As the paper moves through the printer, the solvent is spread across each sheet by an absorbent wick. When the solvent-impregnated paper comes into contact with the waxed original, it dissolves just enough of the pigmented wax to print the image onto the sheet as it goes under the printing drum.
, a cheap, durable pigment that provided good contrast, but 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.
. At one point a teacher hands out a duplicated exam paper and every student in the class immediately lifts it to his or her nose and inhales.
Science fiction fandom
Science fiction fandom or SF fandom is a community or "fandom" of people actively interested in science fiction and fantasy and in contact with one another based upon that interest...
and early comic book fandom to produce fanzines. Sheets printed on such a machine were sometimes called ditto sheets, or just dittos in the U. S. (an example of a genericized trademark
Genericized trademark
A genericized trademark is a trademark or brand name that has become the colloquial or generic description for, or synonymous with, a general class of product or service, rather than as an indicator of source or affiliation as intended by the trademark's holder...
). The term "spirit duplicator" refers to the alcohols which were a major component of the solvents used as "inks" in these machines. They are sometimes confused with the mimeograph, which is actually a different technology.
History
The spirit duplicator was invented in 1923 by Wilhelm Ritzerfeld. The best-known manufacturer in the United States and the world was Ditto Corporation of Illinois, while copiers available in the United Kingdom were commonly manufactured by the Block & Anderson company, under their "Banda" brand. In both cases the trademark became a generic name for both the copiers and the process in their respective markets.The thermofax
Thermofax
Thermo-Fax is 3M's trademarked name for a photocopying technology which it introduced in 1950. It was a form of thermographic printing and an example of a dry silver process. It was a significant advance as no chemicals were required, other than those contained in the copy paper itself...
machine was introduced by 3M
3M
3M Company , formerly known as the Minnesota Mining and Manufacturing Company, is an American multinational conglomerate corporation based in Maplewood, Minnesota, United States....
in the late 1960s and could make a spirit master from an ordinary typewritten or handwritten sheet. The resulting print quality was very poor but the machines were popular because of their convenience.
Spirit duplicator technology gradually fell into disuse starting in the 1970s after the availability of low-cost, high-volume xerographic copiers
Xerography
Xerography is a dry photocopying technique invented by Chester Carlson in 1938, for which he was awarded on October 6, 1942. Carlson originally called his invention electrophotography...
; by the mid 1990s, the use of the technology was rare. The technology remains useful where electrical power is unavailable or where the only remaining originals of legacy documents requiring duplication are in "spirit master" form.
Operation
The duplicator used two-ply "spirit 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 paperCarbon paper
Carbon paper is paper coated on one side with a layer of a loosely bound dry ink or pigmented coating, usually bound with wax. It is used for making one or more copies simultaneous with the creation of an original document...
.) 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.
There is no ink used in spirit duplication. As the paper moves through the printer, the solvent is spread across each sheet by an absorbent wick. When the solvent-impregnated paper comes into contact with the waxed original, it dissolves just enough of the pigmented wax to print the image onto the sheet as it goes under the printing drum.
Colors
The usual wax color was aniline purpleMauveine
Mauveine, also known as aniline purple and Perkin's mauve, was the first synthetic organic chemical dye.Its chemical name is3-amino-2,±9-dimethyl-5-phenyl-7-phenazinium acetate...
, a cheap, durable pigment that provided good contrast, but masters were also manufactured in red
Red
Red is any of a number of similar colors evoked by light consisting predominantly of the longest wavelengths of light discernible by the human eye, in the wavelength range of roughly 630–740 nm. Longer wavelengths than this are called infrared , and cannot be seen by the naked eye...
, green
Green
Green is a color, the perception of which is evoked by light having a spectrum dominated by energy with a wavelength of roughly 520–570 nanometres. In the subtractive color system, it is not a primary color, but is created out of a mixture of yellow and blue, or yellow and cyan; it is considered...
, blue
Blue
Blue is a colour, the perception of which is evoked by light having a spectrum dominated by energy with a wavelength of roughly 440–490 nm. It is considered one of the additive primary colours. On the HSV Colour Wheel, the complement of blue is yellow; that is, a colour corresponding to an equal...
, black
Black
Black is the color of objects that do not emit or reflect light in any part of the visible spectrum; they absorb all such frequencies of light...
, and the hard-to-find orange
Orange (colour)
The colour orange occurs between red and yellow in the visible spectrum at a wavelength of about 585–620 nm, and has a hue of 30° in HSV colour space. It is numerically halfway between red and yellow in a gamma-compressed RGB colour space, the expression of which is the RGB colour wheel. The...
, yellow
Yellow
Yellow is the color evoked by light that stimulates both the L and M cone cells of the retina about equally, with no significant stimulation of the S cone cells. Light with a wavelength of 570–590 nm is yellow, as is light with a suitable mixture of red and green...
, and brown
Brown
Brown is a color term, denoting a range of composite colors produced by a mixture of orange, red, rose, or yellow with black or gray. The term is from Old English brún, in origin for any dusky or dark shade of color....
. All except black reproduced in pastel shades: pink
Pink
Pink is a mixture of red and white. Commonly used for Valentine's Day and Easter, pink is sometimes referred to as "the color of love." The use of the word for the color known today as pink was first recorded in the late 17th century....
, 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
Methanol
Methanol, also known as methyl alcohol, wood alcohol, wood naphtha or wood spirits, is a chemical with the formula CH3OH . It is the simplest alcohol, and is a light, volatile, colorless, flammable liquid with a distinctive odor very similar to, but slightly sweeter than, ethanol...
) was not ink, but a clear solvent.
Paper
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 master could at most print about 500 copies before the pigment was exhausted and the print quality became illegibly faint. If fewer copies were required, the master could be removed from the printing drum and saved for future use.Smell
The aroma of pages fresh off the duplicator combined with the cool touch from the evaporating alcohol was a memorable feature of school life for those who attended in the spirit duplicator era. A pop culture reference to this is to be found in the film Fast Times At Ridgemont HighFast Times at Ridgemont High
Fast Times at Ridgemont High is a 1982 American coming-of-age teen comedy film written by Cameron Crowe and adapted from his 1981 book of the same name...
. At one point a teacher hands out a duplicated exam paper and every student in the class immediately lifts it to his or her nose and inhales.
See also
- Duplicating machinesDuplicating machinesDuplicating 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 limited-run distribution.Like the...
- Fordigraph - historical spirit duplicator supplier
- List of duplicating processes
Further reading
- M P Doss, Information Processing Equipment (New York, 1955)
- Irvin A. Herrmann, Manual of Office Reproduction (New York, 1956)