Editing Mimeograph (section)

==Mimeography process==
The image transfer medium was originally a stencil made from [[wax]]ed [[Rice paper#Mulberry paper|mulberry paper]]. Later this became an immersion-coated long-fiber paper, with the coating being a plasticized [[nitrocellulose]].  This flexible waxed or coated sheet is backed by a sheet of stiff card stock, with the two sheets bound at the top.

Once prepared, the stencil is wrapped around the ink-filled drum of the rotary machine. When a blank sheet of paper is drawn between the rotating drum and a pressure roller, ink is forced through the holes on the stencil onto the paper. Early flatbed machines used a kind of [[squeegee]].

The ink originally had a [[lanolin]] base<ref>[http://chem.5677567.com/formula/mimeograph-ink-vehicle-formula.html Mimeograph Ink Vehicle Formula] {{webarchive|url=https://archive.today/20120709153405/http://chem.5677567.com/formula/mimeograph-ink-vehicle-formula.html |date=2012-07-09 }} Chemical Industry</ref> and later became an oil in water emulsion. This emulsion commonly uses turkey-red oil (sulfated [[castor oil]]) which gives it a distinctive and heavy scent.

===Preparing stencils===
One uses a regular typewriter, with a stencil setting, to create a stencil.  The operator loads a stencil assemblage into the typewriter like paper and uses a switch on the typewriter to put it in stencil mode.  In this mode, the part of the mechanism which lifts the [[typewriter ribbon|ribbon]] between the type element and the paper is disabled so that the bare, sharp type element strikes the stencil directly. The impact of the type element displaces the coating, making the tissue paper permeable to the [[Mineral oil|oil]]-based [[ink]]. This is called "cutting a stencil".<ref name=MimeoTypewriter>{{cite web|title=How to prepare a mimeograph stencil by using a typewriter|url=http://www.sil.org/lingualinks/literacy/implementaliteracyprogram/howtoprepareamimeographstencil2.htm|archive-url=https://archive.today/20121016144524/http://www.sil.org/lingualinks/literacy/implementaliteracyprogram/howtoprepareamimeographstencil2.htm|url-status=dead|archive-date=2012-10-16|work=LinguaLinks Library|publisher=SIL International|access-date=2011-05-10}}</ref>

A variety of specialized [[styluses]] were used on the stencil to render lettering, illustrations, or other artistic features by hand against a textured plastic backing plate.<ref name=MimeoHand>{{cite web|title=How to prepare a mimeograph stencil by hand|url=http://www.sil.org/lingualinks/literacy/implementaliteracyprogram/howtoprepareamimeographstencil1.htm|archive-url=https://archive.today/20111022224825/http://www.sil.org/lingualinks/literacy/implementaliteracyprogram/howtoprepareamimeographstencil1.htm|url-status=dead|archive-date=2011-10-22|work=LinguaLinks Library|publisher=SIL International|access-date=2011-05-10}}</ref>

Mistakes were corrected by brushing them out with a specially formulated [[correction fluid]], and retyping once it has dried. (Obliterine was a popular brand of correction fluid in Australia and the United Kingdom.)<ref name=MimeoCorrect>{{cite web|title=How to correct a mimeograph stencil|url=http://www.sil.org/lingualinks/literacy/implementaliteracyprogram/howtocorrectamimeographstencil.htm|archive-url=https://archive.today/20121016144730/http://www.sil.org/lingualinks/literacy/implementaliteracyprogram/howtocorrectamimeographstencil.htm|url-status=dead|archive-date=2012-10-16|work=LinguaLinks Library|publisher=SIL International|access-date=2011-05-10}}</ref>

Stencils were also made with a thermal process, an infrared method similar to that used by early photocopiers. The common machine was a [[Thermofax]].<ref>{{Cite web |title=Preservation Self-Assessment Program (PSAP) {{!}} Office Printing and Reprography |url=https://psap.library.illinois.edu/collection-id-guide/officeprintcopy |access-date=2023-04-17 |website=psap.library.illinois.edu}}</ref>

Another device, called an [[electrostencil]] machine, sometimes was used to make mimeo stencils from a typed or printed original. It worked by scanning the original on a rotating drum with a moving optical head and burning through the blank stencil with an [[electric spark]] in the places where the optical head detected ink. It was slow and produced [[ozone]]. Text from electrostencils had lower resolution than that from typed stencils, although the process was good for reproducing illustrations. A skilled mimeo operator using an electrostencil and a very coarse [[halftone]] screen could make acceptable printed copies of a photograph.

During the declining years of the mimeograph, some people made stencils with early computers and [[dot matrix printer|dot-matrix impact printers]].<ref name=MimeoDotMatrix>{{cite web|title=How to prepare a mimeograph stencil by using a dot matrix printer |url=http://www.sil.org/lingualinks/literacy/implementaliteracyprogram/howtoprepareamimeographstencil.htm |archive-url=https://archive.today/20080213121240/http://www.sil.org/lingualinks/literacy/implementaliteracyprogram/howtoprepareamimeographstencil.htm |url-status=dead |archive-date=2008-02-13 |work=LinguaLinks Library|publisher=SIL International|access-date=2011-05-10}}</ref>

===Limitations===
Unlike spirit duplicators (where the only ink available is depleted from the master image), mimeograph technology works by forcing a replenishable supply of ink through the stencil master. In theory, the mimeography process could be continued indefinitely, especially if a durable stencil master were used (e.g. a thin metal foil). In practice, most low-cost mimeo stencils gradually wear out over the course of producing several hundred copies. Typically the stencil deteriorates gradually, producing a characteristic degraded image quality until the stencil tears, abruptly ending the print run. If further copies are desired at this point, another stencil must be made.

Often, the stencil material covering the interiors of closed [[letterform]]s (e.g. ''a'', ''b'', ''d'', ''e'', ''g'', etc.) would fall away during continued printing, causing ink-filled letters in the copies.  The stencil would gradually stretch, starting near the top where the mechanical forces were greatest, causing a characteristic "mid-line sag" in the textual lines of the copies, that would progress until the stencil failed completely. 

The [[Gestetner]] Company (and others) devised various methods to make mimeo stencils more durable.<ref name=DupStencil>{{cite web |title=Duplicating stencil |url=http://www.patentstorm.us/patents/4535690/description.html |archive-url=https://archive.today/20130421191131/http://www.patentstorm.us/patents/4535690/description.html |url-status=dead |archive-date=2013-04-21 |work=Patentstorm |access-date=2011-05-10}}</ref>

Compared to spirit duplication, mimeography produced a darker, more legible image. Spirit duplicated images were usually tinted a light purple or lavender, which gradually became lighter over the course of some dozens of copies. Mimeography was often considered "the next step up" in quality, capable of producing hundreds of copies. Print runs beyond that level were usually produced by professional printers or, as the technology became available, [[xerography|xerographic copiers]].