A spirit duplicator was a printing method invented in 1923 by Wilhelm
Ritzerfeld and commonly used for much of the rest of the 20th century. The term
"spirit duplicator" refers to the alcohols which were a major component of
the solvents used as "inks" in these machines. The device coexisted alongside
the mimeograph. Spirit duplicators were used mainly by
schools, churches, clubs, and other small organizations, such as in the
production of fanzines, because of the limited number of copies one could make
from an original, along with the low cost and correspondingly low quality of
copying. History
The spirit duplicator was invented in 1923 by Wilhelm Ritzerfeld. The
best-known manufacturer in the US and the world was Ditto Corporation of
Illinois, while copiers available in the UK 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. Spirit duplicator technology gradually
fell into disuse starting in the 1970s after the availability of low-cost,
high-volume xerographic copiers. By the turn of the 21st century, 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. Tattoo artists use the master copies
these machines produce as the transferred design makes a very durable
print on the skin that resists smudging as excess ink is wiped off during the
process. It is perhaps the only modern-day usage of such a device;
industry-specific machines that produce the prints are now available as artists
in the past have coveted and exhausted the supply of older models leftover.
The faintly sweet aroma of pages fresh off the duplicator was a memorable
feature of school life in the spirit-duplicator era. A pop culture
reference to the aroma can be found in the 1982 film Fast Times At Ridgemont
High. At one point a teacher distributes a duplicated schedule of class quizzes,
and every student immediately lifts it to his or her nose and inhales. The
blues band Saffire - The Uppity Blues Women has another perspective in their
song "School Teacher's Blues," which has the lines, "My fingers have turned
purple, My master's like I chewed it, my mind is getting warped from inhaling
Ditto fluid." Design
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 first sheet transferred the colored wax from the
second sheet to the shiny/coated back side of the first sheet, producing a
mirror image. This produced the same result of a sheet of carbon paper put in
backwards. The two sheets were then separated, and the first sheet was
fastened onto the drum of the machine, with the back side facing out, acting as
a printing plate. There is no separate ink used in spirit
duplication, as the wax transferred to the back side of the first sheet
contained the ink. As the paper to be printed moved through the printer, the
solvent was spread across each sheet by an absorbent wick. When the
solvent-impregnated paper came into contact with the back side of the first
sheet, it dissolved just enough of the pigmented wax to print the image onto
the paper as it went under the printing drum.
= Colors = The usual wax color was aniline purple,
a cheap, moderately 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, and so on. Spirit duplicators had the useful
ability to print multiple colors in a single pass, which made them 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 duplicating fluid was not ink, but a clear solvent.
The duplicating fluid typically consisted of a 50/50 mix of isopropanol
and methanol, both of which were inexpensive, readily available in
quantity, evaporated quickly, and would not wrinkle the paper.
In 1938 a nonflammable solvent was invented by Johan Bjorksten to allow the
possibility of using electrically driven machines without the concern of the
flammability of pure methyl/ethyl alcohol. "A composition composed of 10%
of monofluoro tri-chloro methane and 90% of a mixture of 50% methyl alcohol, 40%
ethyl alcohol, 5% water and 5% of ethylene glycol mono-ethyl ether. This
solvent mixture is non-flammable in the closed space of the reservoir and has a
flash point of 100°F. when fully exposed to air. The solvent mixture has a
pleasant odor, reduced toxicity and gives at least as good copies as the
duplication liquid before the addition of the mono-fluoro tri-chloro methane.
It is believed that the high efficiency of mono-fluoro tri-chloro methane as a
flame reducing agent is due to the fact that its boiling point is sufficiently
low as to cause the formation of a non-flammable vapor, film on the surface
of the organic solvent, with sufficiently high boiling point as to be
substantially retained by the solvents even at high summer temperatures."
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 print about 500
copies before the pigment was exhausted and the print became illegible. If fewer
copies were required, the master could be removed from the printing drum and
saved for future use. Durability
Dittoed copies now pose a serious challenge to archivists responsible for
historic document and artistic preservation. Dittoed images gradually
fade with exposure to ultraviolet light, limiting their usability for permanent
labels and signage. When exposed to direct sunlight, ditto copies can fade
to illegibility in less than a month. The low-quality paper often used would
yellow and degrade due to residual acid in the untreated pulp. In the worst
case, old copies can literally crumble into small particles when handled.
See also Duplicating machines
Hectograph Fordigraph
List of duplicating processes References
Further reading Information Processing Equipment. Edited
by M.P. Doss ... Contributors: Hubbard W. Ballou [and Others], Etc. New York.
1955. Irvin Albert Herrmann. Manual of Office
Reproduction: Reproduction Processes, Systems Duplicating. Office Publishing
Company.