Office Printing and Reprography

"Reprography" is a category that includes copying and duplication processes. Copying, in this arena, refers to the production of a small batch of copies from an original. Duplicating, which encompasses printing processes, refers to the reproduction of virtually limitless copies. Since the emergence of digital tools, the distinction between the two has become less clear as hardware and software utilize and blend both.

Office Printing and Reprographic Processes

"Ink" on Paper

Carbon Copy (1870s – 1980s)
Stencil Copy (1880s – 1970s)
Typography (c. 1902 – c. 1970)
Offset Lithography (Office) (1906 – present) | cf. Offset Lithography (Photo) | Note: This is a different type of lithography than Gel-Lithograph.
Impact Print (1960s – present)

Carbon Copy

Carbon transfer sheet — Unused carbon transfer sheet.

Carbon copy onionskin paper — Carbon copy on onionskin paper. Note the onionskin manufacturer's watermark. Taken from an image of the ILIR Library Teamsters Contracts Vertical File, 1948-69 (35/3/415) from the University Archives. Image courtesy of the University of Illinois Board of Trustees.

Blue carbon copy paper — Blue carbon copy sheet labeled "COPY". Taken from an image of the ILIR Library Teamsters Contracts Vertical File, 1948-69 (35/3/415) from the University Archives. Image courtesy of the University of Illinois Board of Trustees.

Carbon copy on wrinkled manifold paper — Carbon copy text on wrinkled manifold paper. Taken from an image of the ILIR Library Teamsters Contracts Vertical File, 1948-69 (35/3/415) from the University Archives. Image courtesy of the University of Illinois Board of Trustees.

Carbon copy on wrinkled manifold paper in raking light — Carbon copy text on wrinkled manifold paper photographed in raking light. Taken from an image of the ILIR Library Teamsters Contracts Vertical File, 1948-69 (35/3/415) from the University Archives. Image courtesy of the University of Illinois Board of Trustees.

Adhesive damage on backside of carbon paper tissue — Back side (verso) of carbon paper with evident adhesive tape damage. Taken from an image of the ILIR Library Teamsters Contracts Vertical File, 1948-69 (35/3/415) from the University Archives. Image courtesy of the University of Illinois Board of Trustees.

Synonyms

Carbon paper
Manifold copy
Onionskin copy

Dates

Patented 1806, popular 1870s – 1980s

Prevalence

Very common

Support

Thin, semi-translucent paper (tissue, onionskin, manifold)

Paper Fibers

Visible

Paper Color

White or canary

Image/Text Tone

Monochrome (black, blue, violet, or red)

Description

Carbon copies may be typewritten or handwritten. Although it can come in nearly any color, carbon copy text will always be of a single color; and, the text will tend to be faint and dull. Black text is generally carbon pigment in a wax or oil base, and it will appear unfaded. Color text is aniline dye-based (likely blue, violet, red); these will often exhibit fading. Aniline dyes were used in both typewriter color ribbon and carbon papers (purple, blue, red inks). If the sheet bears more than one ink color and is opaque, it is likely the original top copy and thus not technically a carbon copy. Carbon copy text will lack the embossed quality of the directly typewritten top copy.

Carbon copies are usually made on crisp, semi-translucent paper. Because it is essentially a thin tissue paper, carbon copy paper wrinkles easily but is actually quite strong. This paper may either be made of durable rag-stock ("onionskin") or a low-grade wood pulp (manifold paper). It typically is a white or canary color with an unglazed, sometimes cockled surface. Image and/or text will be slightly waxy or greasy; it will appear to float on the paper surface when viewed under low magnification. Each successive layer in the copy set will be appear more blurry, with ever lessening contrast. Copies tend to smudge very easily. When carbon copies are found along with their corresponding top copy sheet, this usually indicates that it was an outgoing document.

Composition

Support	Image/Text
Paper (uncoated)	Wax- or oil-based carbon black or color ink (w/ aniline dye)

Deterioration

Copies in black are generally carbon black pigment with a wax or oil base, and they are therefore stable. Any color other than black may be water-soluble and should be considered very light sensitive. Color ink may appear faded. Smudged image and/or text is common in either case. Manifold copy papers are composed of a low-grade wood pulp, which is very thin and weak and which should be assumed acidic. Onionskin copy papers are far more stable supports because they are made from cotton fiber.

Risk Level

Low. Black ink carbon copies (carbon black pigment) are low risk; color ink (aniline dye-based) copies are at a higher risk, but still rather stable. Copies on an acidic manifold paper support is of higher preservation priority than the relatively stable onionskin paper.

Process

Carbon paper is a duplication process, as copies are created at the same time the original is drafted. The carbon sheet, which has been back-coated with "ink" (pigment and oil/wax), is placed behind the original draft, with a sheet of copy paper (onionskin or manifold) behind them. If more than one copy is desired, additional carbon sheets are sandwiched between copy papers. Through the pressure of typewriter glyphs, a pen, or stylus, the pigment-and-wax "ink" is transferred to the copy paper(s) positioned behind the carbon sheet(s).

Background

Carbon paper was patented by Ralph Wedgwood as part of his Manifold Stylographic Writer system in 1806. This system was designed to make simultaneous copies of handwritten documents. The process was later marketed as a "copy book" or Stylograph. Carbon paper was frequently used to make copies of typewritten documents. Carbon copies are among the most common reprographic formats found in 20th century paper collections.

Storage Environment

Cool storage (below 50 degrees) is recommended, and colder is generally better. Allowable Fluctuation: ±2°F; ±3% RH

Temp.	35–65°F (2–18°C)
RH	35–50% RH

Storage Enclosure(s)

Loose, unbound records should be stored in acid-free file folders. Folders should be placed in acid-free or low-lignin archival boxes. Alternatively, folders may be stored in steel filing cabinets with a baked enamel finish. Care must be taken not to overfill folders and boxes. Documents should fit easily in folders and boxes; they should not be forced into enclosures that are too small. Spacer boards, which can be created using scored and folded acid-free board, may be placed in underfilled boxes to prevent folders from slumping or bending.

Storage Orientation

Carbon copies should be stored vertically in file folders, which are placed vertically inside acid-free storage boxes or steel filing cabinets.

Display Recommendations

Responsible display practices ensure the long-term preservation of collections. Facsimiles should be used whenever possible, and paper artifacts should not be displayed permanently. Light levels in the exhibition area should be kept low. Appropriate filters should be used to minimize exposure to ultraviolet light. Display cases should be enclosed and sealed to protect their contents, and their items should be securely framed or matted using preservation-quality materials that have passed the Photographic Activity Test (ISO 18916:2007).

Black ink copies are generally quite stable and may be displayed. They should not be exposed to more than 30,000+ ft-c hours (300,000 lux hours) per year, and they should have a 1-year rest between displays. Color ink copies made using aniline dyes are highly sensitive to light. They should not be exposed to more than 5,000 ft-c hours (50,000 lux hours) per year, and they should have a 3-year rest between displays.

Stencil Copy

Detail of stencil printed text. Note the blobby, inconsistent characters and oil-based ink halos. Taken from an image of the ILIR Library Teamsters Contracts Vertical File, 1948-69 (35/3/415) from the University Archives. Image courtesy of the University of Illinois Board of Trustees.

Stencil printed text exhibiting slight oil-based ink halos due to oil in the ink bleeding into the paper. Taken from an image of the ILIR Library Teamsters Contracts Vertical File, 1948-69 (35/3/415) from the University Archives. Image courtesy of the University of Illinois Board of Trustees.

Stencil print ink transferred to verso of preceding sheet. Taken from an image of the ILIR Library Teamsters Contracts Vertical File, 1948-69 (35/3/415) from the University Archives. Image courtesy of the University of Illinois Board of Trustees.

Synonyms

Cyclostyle
Mimeograph
Dermaprint
Dermatype
Gestetner
Trypograph
Papyrograph
Roneo
Edison autographic press
Edison Electric Pen

Dates

1880s – 1970s

Prevalence

Common

Support

Plain, fibrous paper

Paper Fibers

Visible

Image/Text Tone

Monochrome (carbon black, blue, violet)

Description

Stencil copies are usually printed on rough and porous plain paper with evident fibers, which provided optimal ink absorption. Image/text is often in black ink, but sometimes color dye inks (typically blue or violet) are used. Oil-based ink will cause slight toning around the printed image/text (a "halo" effect). Stencil images/text will have a clotted or stippled appearance. Closed characters (e.g. "o," "8") may appear as ink blobs due to stencil fall-out. As this is a wet ink process, ink streaking and "ghosted" reverse text may have transferred to the sheet verso from a previous (wet) print in the stack. Print quality may also bear resemblance to that of a spirit duplicate and hectograph, particularly those made with aniline color ink.

Composition

Support	Image/Text
Paper (uncoated)	Oil-based carbon black or color ink (w/ aniline dye)

Deterioration

Oil-based inks produce relatively stable image/text. The water-soluble inks of early stencil copies, which often contained ink carriers (e.g. glycerine) and aniline colorants, make for very unstable prints. Permanence will depend greatly upon the quality of the paper support.

Risk Level

Low. Color prints on poor-quality support present a higher risk. Permanence will depend greatly upon the quality of the paper support.

Process

All stencil copying/duplication processes are essentially the same. To print a positive copy, a stencil is produced by reduction and then ink is forced through this stencil using pressure applied with a squeegee, roller, flat-bed press, or drum. The means of stencil creation will vary from freehand perforation by pen in the nineteenth century to mechanical reduction (e.g. typewriter, thermal, computer-aided) in the twentieth century.

Background

Stencil duplication is a broad category encompassing all processes that involve ink-and-stencil printing. Originally a method of manuscript copying using Cyclostyle and Neostyle pens in the 1870s, stencil duplication became commercially viable in the 1880s with the introduction of the mechanized Mimeograph process, allowing typewriters to create stencil masters. From then throughout the twentieth century, stencil copy was chiefly focused on typescript, when rotary stencil machines (e.g. Mimeograph, Gestetner, Roneo) appeared. Stencil machines were a common and economical printing method for small print runs in office, school, and church settings. Early fanzines were also often printed this way. By the 1970s, stencil copying had more or less been phased out by photocopying and offset printing. In some corners of publishing, use of stencil machines still persists today, albeit prepared digitally.

Storage Environment

Cool storage (below 50 degrees) is recommended, and colder is generally better. Allowable Fluctuation: ±2°F; ±3% RH

Temp.	35–65°F (2–18°C)
RH	35–50% RH

Storage Enclosure(s)

Storage Orientation

Stencil copies should be stored vertically in file folders, which are placed vertically inside acid-free storage boxes or steel filing cabinets.

Display Recommendations

Typography

Letterpress printed notice — Letterpress typographic notice. Courtesy of the Illinois History and Lincoln Collections, University Library, UIUC, University of Illinois Board of Trustees.

Letterpress printed sign — Letterpress typographic print. Courtesy of the Illinois History and Lincoln Collections, University Library, UIUC, University of Illinois Board of Trustees.

Synonyms

Letterpress
Multigraph
Typographic copying

Dates

c. 1902 – c. 1970

Prevalence

Moderately rare

Support

Varies in color, type, and size; did not require specialized paper.

Paper Fibers

Visible

Image/Text Tone

Carbon black or color ink (blue, violet, red)

Description

Typographic copies are difficult to distinguish from typed originals, stencil copies, hectographs, lithographs, and spirit duplicates. Ink used for typographic printing was typically oil-based carbon black, but it could be any standard printer ink. The text of typographic copies appears neat, well-spaced, and crisp since it is set from type. Due to the pressure of the printing process, typographic copies will typically exhibit more visible embossment, especially of smaller characters, on their verso side. As this is a wet ink process, ink streaking and ghosted reverse text may have transferred to the sheet verso from a previous (wet) print in the stack. Oil-based ink will cause slight toning ("halo") around the printed image/text. Text will most likely be black but is possibly violet, blue, or red. Often used for forms or promotional materials, typographic copies were usually produced in large quantities.

Composition

Support	Image/Text
Paper (uncoated)	Oil-based carbon black or color ink (w/ aniline dye)

Deterioration

Carbon black text copies will present little to no preservation issues other than those of the paper support. Colored inks will likely contain aniline dyes and therefore will be prone to fading and running, in the case of water exposure.

Risk Level

Low. Black copies made with carbon black pigment are a low preservation risk. Color copies are a moderate preservation risk, due to the light and water sensitivities of aniline dyes.

Process

Typographic copies were produced on flat-bed or rotary machines. In flat-bed machines, individual letters of type were composed and locked into a flat plate, which was then inked. Paper placed against the inked plate would produce a copy of the set type. Rotary presses worked in the same manner, but with the type set around the outer surface of a drum rather than a plate. Rotary presses were turned by a crank or electric motor. Some typographic copy machines like the Addressograph and Addressing Multigraph were designed specifically for addressing correspondence. These machines used embossed metal plates rather than moveable type.

Background

Typographic copying, or letterpress printing, had limited office applications from about 1902 to 1970. Typographic copy machines designed for office use were small-scale letterpress machines that made small runs of copies. The Multigraph was the earliest typographic copy machine; it made copies using moveable type and carbon paper. Later typographic copy machines include the Roneotype, Printograph, and Planotype.

Storage Environment

Cool storage (below 50 degrees) is recommended, and colder is generally better. Allowable Fluctuation: ±2°F; ±3% RH

Temp.	35–65°F (2–18°C)
RH	35–50% RH

Storage Enclosure(s)

Loose, unbound records should be stored in acid-free file folders. Folders should be placed in acid-free or low-lignin archival boxes. Alkaline storage enclosures are not advised for typographic copies, which may contain aniline dyes. Alternatively, folders may be stored in steel filing cabinets with a baked enamel finish. Care must be taken not to overfill folders and boxes. Documents should fit easily in folders and boxes; they should not be forced into enclosures that are too small. Spacer boards, which can be created using scored and folded acid-free board, may be placed in underfilled boxes to prevent folders from slumping or bending.

Storage Orientation

Letterpress prints should be stored vertically in file folders, which are placed vertically inside acid-free storage boxes or steel filing cabinets.

Display Recommendations

Offset Lithography (Office)

Synonyms

Offset litho
Multilithing
Rotaprinting
Offset duplication
Offset printing
Photo-offset

Dates

1906 – present; office use declines after 1960s

Prevalence

Common in general printing applications. Moderately rare in office applications.

Support

Plain paper

Paper Fibers

Visible

Image/Text Tone

Monochrome (carbon black or numerous other color inks)

Description

Lithographic copies may include handwriting, typescript, or graphic material. Oil-based inks will cause slight toning around the printed image/text (a "halo" effect). Lithography, or some derivative form, is the process by which most commercial and widely distributed textual material was printed in the twentieth century. Since its use as an office printing process was modest, its identification as such, in terms of preservation, is not essential. Early forms of office lithographic copies (text) are difficult to differentiate from stencil copies. They will be qualitatively identical to most oil-based carbon black inks, and they are therefore stable.

Composition

Support	Image/Text
Paper (uncoated)	Oil-based carbon black or color ink (w/ aniline dye)

Deterioration

Oil-based ink is fairly stable and is water insoluble. Carbon black ink will be resistant to fading. Other colors will likely contain aniline dyes (water-soluble); they will therefore be prone to light-fading and running if exposed to either water or extremely high humidity.

Risk Level

Moderately low. Low (black ink) to moderate (color inks). Permanence will depend greatly upon the quality of the paper support.

Process

Lithographic printing is based on the principle that water and oil do not mix. All lithographic processes involve a printing plate that is treated such that oil-based ink adheres to the image/text areas and is repelled by the non-image/ text areas. The plate may be paper or plastic (for making just a few copies), or aluminum or zinc (most common; for larger runs of copies). The surface of the plate was then treated to make it attract water, such as by applying gum. The image/text was applied in a variety of ways using oil-based ink, such as by typing directly onto the plate or using a prepared stencil master to stencil the image. A blank piece of paper applied to the plate with some pressure then yields a copy.

Background

Early lithography was invented by Alois Senefelder in 1798 and was done on metal. While lithography is most synonymous with fine art reproduction, offset paper lithography has been used in commercial and office settings for over 100 years. Offset lithography on paper was introduced around 1906 and was popular for industrial-level printing and the rapid production of large runs of material. Compared to other printing processes, offset lithography is best suited for producing large volumes of high-quality prints. However, offset copying machines like the Autocopyist and the Roneo-Litho were also produced for use in offices in the early twentieth century.

Storage Environment

Cool storage (below 50 degrees) is recommended, and colder is generally better. Allowable Fluctuation: ±2°F; ±3% RH

	Ideal
Temp.	35–65°F (2–18°C)
RH	35–50% RH

Storage Enclosure(s)

Storage Orientation

Offset lithographic prints should be stored vertically in file folders, which are placed vertically inside acid-free storage boxes or steel filing cabinets.

Display Recommendations

Impact Print

Synonyms

Dot-matrix print
Daisy wheel print
Line print

Dates

1960s – present

Prevalence

Fairly common

Support

Plain copy paper

Paper Fibers

Highly visible

Image/Text Tone

Monochrome (black [most common], blue, violet, red)

Description

Impact prints are qualitatively (and often chemically) similar to any typewritten document, although they often come from a digital source. In fact, daisy wheel technology was used in both computer printers and electronic typewriters of the 1970s and 1980s. Characters from an impact printer will either appear as: crisp, well-defined glyphs (if from a daisy wheel printer), oddly-aligned rows (if from a line print), or comprised of evenly spaced, fuzzy dots (if from a dot-matrix printer). On close inspection, the ink appears penetrate the paper and the paper fibers are visible through the ink. "Black" text will likely appear gray-black. Color text is less common, but text using blue, violet, or red ink can be found. Color impact printing generally looks faded, streaky, and sometimes smeared. Dot-matrix printers are still used for tickets or receipts. Daisy wheel printers, which are now obsolete, were generally used for high-quality print applications where presentation was a consideration (i.e. in offices).

Composition

Support	Image/Text
Paper (uncoated)	Wax- or oil-based carbon black or color ink (will contain aniline dyes)

Deterioration

Stability will vary depending on the ink. Oil-based or wax-based ink carrying a black pigment will be relatively stable, whereas water-based ink carrying a colored aniline dye will be far less stable. Continuous feed paper stock used in dot-matrix and line printers were often wood-free, meaning that the lignin had been removed; yellowing and/or embrittlement of the paper is therefore rare.

Risk Level

Low. Black ink is a carbon-based pigment and is fairly permanent. Color inks should be assumed water-soluble and not stable. Dot-matrix and line prints will often hold up well, having avoided yellowing and embrittlement due to the lack of wood in their paper stock.

Process

Impact prints are copies produced from an electronic file rather than a hard-copy original. Impact prints may be created using one of three types of prints: dot-matrix, daisy wheel, or line printers. Similar to typewriters, all use an inked ribbon that transfers ink to paper via impact on the ribbon. The resulting prints are generally of a lower quality than those produced using inkjet or laser printers, but they are also cheaper.

Background

Impact printers were commonly used in offices in the 1960s and 1970s, and they continued to be popular as use of personal computers increased in the 1980s. Impact prints were an inexpensive method of printing from an electronic file. Throughout the 1990s, impact printers became less popular as the use of laser and inkjet printers increased. Use of dot-matrix printing persists in many forms, although it is primarily now used for compact, low-end applications like printing tickets and receipts. Full-size dot-matrix printers utilizing tractor feed paper are also still used to print multi-part stationery for businesses like banks and auto repair shops.

Storage Environment

Cool storage (below 50 degrees) is recommended, and colder is generally better. Allowable Fluctuation: ±2°F; ±3% RH

Temp.	35–65°F (2–18°C)
RH	35–50% RH

Storage Enclosure(s)

Storage Orientation

Impact prints should be stored vertically in file folders, which are placed vertically inside acid-free storage boxes or steel filing cabinets.

Display Recommendations

Hectograph Copy (Office)

Synonyms

Gelatin duplication
Jellygraph
Anilin process (sic)
Chromograph (in UK)
Composition pad
Copygraph
Gelatine pad
Dry copy
Hektograph
Polygraph

Dates

1878 - 1970s

Prevalence

Fairly common

Support

Plain paper, often with gelatin or alum/rosin sizing agent.

Paper Fibers

May or may not be visible, depends on paper coating

Image/Text Tone

Monochrome (violet or blue, sometimes other colors)

Description

Hectograph image/text is commonly a violet or blue color that is made from aniline dyes. The paper is often bright white with a smooth, heavily finished surface to control ink use. Hectography was used for both handwritten and typewritten documents, and it was often used to duplicate course materials and publications for small clubs and churches. Technical drawings and graphic art were seldom duplicated in this fashion. Hectographs are nearly indistinguishable and chemically similar (aniline ink) to diazos and spirit duplicates.

Composition

Support	Image/Text
Paper with gelatin or alum/rosin sizing	Aniline dye ink

Deterioration

An image/text composed of aniline dye ink is light sensitive and to some extent water soluble. Alkaline enclosures and treatments will cause discoloration due to the pH sensitivity of aniline dye. Residual acidic processing chemicals on the copy paper could accelerate breakdown. Alum/rosin sizing, which is impregnated in most copy papers, will lead to embrittlement and yellowing of the paper support; high temperature and relative humidity will accelerate deterioration. Permanence will depend greatly upon the quality of the paper support.

Risk Level

Moderate. Aniline dyes are sensitive to light and water. Alkaline enclosures should be avoided. Permanence will depend greatly upon the quality of the paper support.

Process

Hectographic duplication involved typing or writing a master document in hectographic (aniline) ink. Once dry, the master would be pressed face down onto the gelatin-and-glycerin pad surface and left to allow the ink to transfer as a negative image. An alternate method for applying ink to the pad involved the use of a stencil. In either case, the pad was then pressed in contact with copy paper, which absorbed the aniline ink, resulting in a final positive copy. Hectographs could typically produce 40 to 60 copies, each successively lower contrast than the preceding copy.

Background

The hectographic process emerged as a result of the introduction of aniline inks. It became common as an office duplication process around 1878. Hectographs at that time were regarded as the most practical method of office reprography and rose in public favor quickly. By the mid-twentieth century, hectography was a common and economical printing method for an array of limited run applications (i.e. office copies, classroom materials, and church ephemera). Early fanzines were also printed this way. Hectography was gradually displaced by spirit and stencil duplication beginning in the 1950s and altogether phased out by photocopying in the 1970s.

Storage Environment

Cool storage (below 50 degrees) is recommended, and colder is generally better. Allowable Fluctuation: ±2°F; ±3% RH

Temp.	35–65°F (2–18°C)
RH	35–50% RH

Storage Enclosure(s)

Loose, unbound records should be stored in acid-free file folders. Folders should be placed in acid-free or low-lignin archival boxes. Alkaline storage enclosures are not advised for hectographs. Alternatively, folders may be stored in steel filing cabinets with a baked enamel finish. Care must be taken not to overfill folders and boxes. Documents should fit easily in folders and boxes; they should not be forced into enclosures that are too small. Spacer boards, which can be created using scored and folded acid-free board, may be placed in underfilled boxes to prevent folders from slumping or bending.

Storage Orientation

Hectographs should be stored vertically in file folders, which are placed vertically inside acid-free storage boxes or steel filing cabinets.

Display Recommendations

Hectographs were made using aniline dyes that are highly sensitive to light. They should not be exposed to more than 5,000 ft-c hours (50,000 lux hours) per year, and they should have a 3-year rest between displays.

Spirit Duplicate

Spirit duplicate in bound volume — Spirit duplicate in a bound volume. Image courtesy of Ian Batterham.

Spirit duplicate in bound volume on yellowing paper — Spirit duplicate in a bound volume on yellowing paper. Image courtesy of Ian Batterham.

Spirit duplicate master for classroom worksheets — Spirit duplication master for printing classroom worksheets.

Synonyms

Ditto copy
Liquid hectograph
Hectograph spirit duplicating
Roneo

Dates

1923 – 1970s

Prevalence

Fairly common

Support

Plain paper, often with gelatin or alum/rosin sizing agent

Paper Fibers

May or may not be visible depending on support paper

Image/Text Tone

Monochrome (violet, blue, or black)

Description

Image/text color most often purple ("crystal violet") but may be blue or black. The image/text was formed using aniline dye in wax (soluble in a hydrocarbon spirit). Background is white or slightly tinted, with a heavily finished, glossy surface (to control ink use) and visible paper fibers. Spirit duplication was mostly used to copy typewritten documents; handwriting and drawings are common, but less so. "Dittos" were used for both handwritten and typewritten documents, often used to duplicate course materials and small-run church and club organizational publications. Copied text lacks the embossed quality of original typescript; characters will lack crisp edges, and they can appear alternatively blotted or ghostly. Spirit duplicates bear strong resemblance to hectographs, including the "crystal violet" color and tendency of characters to appear fuzzy.

Composition

Support	Image/Text
Paper treated w/ gelatin or alum/rosin sizing	Aniline dye in wax

Deterioration

Aniline dye ink is very light sensitive and therefore prone to fading over time. Aniline dyes, even in a wax-based ink, may run when exposed to water. Alkaline enclosures and treatments should be avoided as they might cause discoloration due to the pH sensitivity of aniline dye. Paper discoloration is common and may also result in an overall lower contrast.

Risk Level

Moderate. Under intense UV light, spirit duplicates can fade to illegibility in less than a month. The common paper support is of low quality, and will yellow and become brittle due to residual acid. At its worst, these copies can literally crumble into small particles when handled.

Process

The negative master is produced by writing or typewriting on a sheet backed with carbon pigment and aniline dye suspended in a wax binder. The dye component is soluble in alcohol-based fluid and is transferrable by pressure. The master is then a reverse image of the text, which is fastened to the cylinder of a rotary printing surface, with the the ink image facing outward. Copy papers wetted with the duplication fluid ("spirit") are then run under the cylinder, at once dissolving and transferring the ink to their surface.

Background

A spirit duplicate is typically referred to as a "ditto" copy. The process is considered the evolution of the hectographic process and was invented by Wilhelm Ritzerfeld in 1923. By the mid-twentieth century, spirit duplication was a common and economical printing method for small organizations printing in limited quantities (i.e. office copies, classroom materials, club newsletters, and church ephemera). Early fanzines were also produced this way. Instead of an ink-transmitting gelatin pad, spirit duplication incorporates a waxy, paste-like ink that is partially dissolved with the application of a hydrocarbon spirit solvent. Over time, some of the chemicals involved were understood to be very unsafe. By the 1970s, spirit duplication was replaced by photocopying and offset printing.

Storage Environment

Cool storage (below 50 degrees) is recommended, and colder is generally better. Allowable Fluctuation: ±2°F; ±3% RH

Temp.	35–65°F (2–18°C)
RH	35–50% RH

Storage Enclosure(s)

Loose, unbound records should be stored in acid-free file folders. Folders should be placed in acid-free or low-lignin archival boxes. Alkaline storage enclosures are not advised for spirit duplicates. Alternatively, folders may be stored in steel filing cabinets with a baked enamel finish. Care must be taken not to overfill folders and boxes. Documents should fit easily in folders and boxes; they should not be forced into enclosures that are too small. Spacer boards, which can be created using scored and folded acid-free board, may be placed in underfilled boxes to prevent folders from slumping or bending.

Storage Orientation

Spirit duplicate prints should be stored vertically in file folders, which are placed vertically inside acid-free storage boxes or steel filing cabinets.

Display Recommendations

Spirit duplicates were made using aniline dyes that are highly sensitive to light. They should not be exposed to more than 5,000 ft-c hours (50,000 lux hours) per year, and they should have a 3-year rest between displays.

Photostat Copy (Office)

Office photostat copy black ground white text — Photostat office copy - negative image. Courtesy of the Illinois History and Lincoln Collections, University Library, UIUC, University of Illinois Board of Trustees.

Office photostat copy white ground black text — Photostat office copy - positive image. Courtesy of the Illinois History and Lincoln Collections, University Library, UIUC, University of Illinois Board of Trustees.

Synonyms

Photostatic Print
Rectigraph

Dates

1909 – 1970s; use declines after 1950

Prevalence

Fairly common

Support

Sensitized photographic paper (without baryta layer)

Paper Fibers

Not visible

Image/Text Tone

Monochromatic white text on black background (negative image) or black text with white background (positive image)

Description

The image may be negative or positive, although negatives (white image/text on black background) are more common. Similar to silver gelatin prints, the image/text is comprised of silver particles. Copies are qualitatively similar to silver gelatin black-and-white photographs, including the tendency to exhibit silver mirroring. The paper is thinner than most photographic paper, since it lacks a baryta layer and has thinner emulsion. Copies may have rough edges and occasionally odd dimensions because they were cut from rolls.

Composition

Support	Binder	Image/Text
Paper (specially coated)	Gelatin	Silver

Deterioration

Preservation of photostatic prints is nearly identical to the preservation properties of silver gelatin DOP prints. For more information, see Silver Gelatin (DOP)Print. Like other silver images, photostats are very sensitive to light and will fade through prolonged exposure. Similarly, they are prone to silver mirroring and may yellow significantly, especially if they were not properly processed or washed.

Risk Level

Moderately low. Protect photostats from prolonged light exposure as they are as photosensitive as any silver gelatin print.

Process

Photostat copy machines were basically large cameras that used a prism to produce a right-reading image. Each exposure produced one print, usually a negative (black background with white text). In 1953, Kodak released a direct-positive paper, allowing for the production of positive copies from a positive original. A positive image could also be produced by creating a negative copy and copying the negative again to create a positive copy. After exposure, the paper was cut from the roll and placed in a developing bath beneath the camera, then a fixer bath. The print was then washed in water, with excess water removed using a squeegee after taking the print out of the final bath. The print was finally dried by pressing between blotters, passing through a set of heated rollers, or dried face-down on glass (this would result in a glossy finish).

Background

Photostatic prints mark the beginning of true copies made through photographic methods. The Rectigraph, which was manufactured in Rochester, NY beginning in 1909, was the first commercially produced photostatic copy machine. The Rectigraph company later became the Rectigraph Division of Haloid in 1937, and later still Haloid-Xerox in 1958. The company was merged into the Xerox Corporation in 1961. The Photostat copy machine was developed by Photostat Ltd. shortly after the Rectigraph. Two other photostatic copy machines, produced specifically for the reproduction of library catalog cards, were the Photoclerk (Anken Chemical and Film Corporation) and Dexigraph (Remington Rand). Photostatic copy machines were large and required a specialist operator. The Photostat was so popular during the height of its use that the name became a common noun to refer to all copies produced by a photostatic copying process.

Storage Environment

Cool storage (below 50 degrees) is recommended, and colder is generally better. Allowable Fluctuation: ±2°F; ±3% RH

Temp.	35–65°F (2–18°C)
RH	35–50% RH

Storage Enclosure(s)

Storage Orientation

Photostatic prints should be stored vertically in file folders, which are placed vertically inside acid-free storage boxes or steel filing cabinets.

Display Recommendations

If the print appears well-processed and stable, it may be displayed for up to 30,000+ ft-c hours (300,000 lux hours) per year with a 1-year rest between displays. Photostat prints were often poorly processed, however, so a more conservative approach to display may be required (5,000 ft-c hours [50,000 lux hours] per year with a 3-year rest between displays).

Diffusion Transfer

Verso (back side) of diffusion transfer paper showing Gevaert brand name.

Splotchy diffusion transfer — Diffusion transfer with overall brown discoloration (front).

Diffusion transfer back side — Diffusion transfer (back).

Diffusion transfer recto and verso views — Diffusion transfer (front). Image courtesy of Ian Batterham.

Diffusion transfer verso (back). Image courtesy of Ian Batterham.

Diffusion transfers exhibiting silvering effect, much like silver gelatin photographic prints. Image courtesy of Ian Batterham.

Synonyms

Diffusion transfer reversal
Chemical transfer
Reflex transfer Copyrapid (Agfa)
Gevacopy (Gevaert)
Verifax (Kodak)
Diaversal
Copyproof

Dates

1940 – c. 1970

Prevalence

Moderately rare

Support

Specially-coated paper

Paper Fibers

May or may not be visible, depends on support paper

Image/Text Tone

Monochrome (black or brown)

Paper Tone

Light brown or gray/buff

Description

Gelatin layer sits on top of the paper with the dye components slightly penetrating the fibers, which is evident under low magnification (10x–30x). Sheets may bear the paper type or manufacturer’s backprint (e.g. Kodak, Gevaert, Agfa). Cut corners are also an identifier for Kodak papers, both for the positive and negative papers. Blotchy water staining and fingerprinting may also be apparent on the back. Image/text contrast may be low, especially for faded inks on a brown background. Diffusion transfers are bi-tonal and cannot reproduce continuous tone or halftone images well. Although a positive copy is considered the end product and focus of this profile, the intermediate negative may also sometimes be found among collections. Sheets have tendency to curl slightly. Diffusion transfer sheets are thicker than most thermally processed copies.

Composition

Support	Binder/Emulsion	Image/Text
Paper (specially coated)	Gelatin	Silver sulfide, silver halide, elemental silver

Deterioration

Final copy is chemically similar to black-and-white gelatin silver photographs, therefore preservation aspects are also similar. What sets diffusion transfers apart is that they will often contain many residual chemicals, precipitating advanced staining, embrittlement, and silver mirroring. Sheets will have a tendency to curl slightly.

Risk Level

Moderate. Protect diffusion transfer prints from prolonged light exposure as they are as photosensitive as any silver gelatin print.

Process

Diffusion transfer copy process is a reflex method based on silver halide chemistry, similar to that of black & white gelatin silver photographs. Two sheets are used in the copy process: a photosensitive sheet with a silver gelatin emulsion and a sheet coated with a gelatin emulsion containing an image-fixing solution (sodium thiosulfate). In the process, light is reflected from an original sheet to make a negative image on the silver gelatin photo emulsion of another sheet. Once exposed to light, the negative copy is developed in an alkaline activator solution to develop/tan the emulsion, resulting in a differential hardening of the gelatin layer between the image and non-image areas. The image is then transferred through pressure to a special copy paper. This is the final copy: a positive image composed of alkaline gelatin, silver salts, reduced silver, thiosulfate and a dye.

Background

The diffusion transfer process was first developed in 1940 but was not popularly adopted until the 1950s. The three most popular brands of diffusion transfer products were Copyrapid (Agfa), Gevacopy (Gevaert), and Kodak, although other companies also produced diffusion transfer products. The process was closely related to direct photocopying and reflex photocopying, and it was an important precursor to the development of instant photography and the Polaroid land camera, which was first sold in 1949. By the end of the 1960s, the diffusion transfer process was rarely used in the document copying realm.

Storage Environment

Cool storage (below 50 degrees) is recommended, and colder is generally better. Allowable Fluctuation: ±2°F; ±3% RH

Temp.	35–65°F (2–18°C)
RH	35–50% RH

Storage Enclosure(s)

Storage Orientation

Diffusion transfer prints should be stored vertically in file folders, which are placed vertically inside acid-free storage boxes or steel filing cabinets.

Display Recommendations

Although similar to silver gelatin photographs, diffusion transfer prints frequently contain residual chemicals, making them particularly sensitive to light. As a result, a conservative approach to display may be required of 5,000 ft-c hours [50,000 lux hours] per year with a 3-year rest between displays.

Dual Spectrum

Unused Dual Spectrum sheets — Unused dual spectrum sheets. Image courtesy of Ian Batterham.

"Blue flame" dual spectrum manufacturer logo, which is often found on verso (back) of sheet.

Dates

1963 – early 1970s

Prevalence

Fairly common

Support

Paper with acrylic coating

Paper Fibers

Not visible

Paper Tone

Pastel pink or cream colored

Image/Text Tone

Monochrome (dark red-brown or black)

Description

Dual spectrum copies can be identified by a distinctive flame emblem (usually light blue) on the verso of the final copy. Image/text is clear and sharp, ranging from dark red brown to black. The image/text could be copied from any original document, including those that were handwritten or typed by various methods. As a result, there is no uniform appearance to the text of dual spectrum copies, other than sharp quality of the image reproduction (unless it was produced from an original document of poor quality) and the text color. The paper ground may be pinkish or cream. The special coated paper used to create dual spectrum copies was available in a range of weights and varies from flimsy to bond weight.

Composition

Support	Binder/Emulsion	Image/Text
Specially coated paper	Acrylic	Metallic silver

Deterioration

Dual spectrum prints are relatively stable and deteriorate in a manner similar to silver gelatin photographic prints. They may exhibit silver mirroring as a result of oxidation. The silver salts contained in the paper coating are somewhat acidic and may cause the paper support to deteriorate over time.

Risk Level

Moderate. Protect dual spectrums from prolonged light exposure as they are as photosensitive as any silver gelatin print.

Process

The dual spectrum process involves the use of two sheets. The first sheet is used to create a photographic copy of the original document. This intermediate sheet was made of thin Mylar or tissue paper and was coated with an oxidant and coupler. The sheet was placed in contact with the image side of the original and placed into the copy machine that exposed the composite from the film side to a powerful tungsten light. The coating on the sheet reacted with the light to produce an inert product, leaving a pattern of unreacted material corresponding to the original image. The exposed intermediate sheet was then placed in contact with a receptor sheet of paper with a coating of acrylic containing silver salt. The sheets were run past an infrared source (e.g. Thermofax copy machine). The unreacted areas of the intermediate sheet would heat up causing the oxidant to vaporise. The vaporized oxidant reacted to the silver salt in the receptor paper, producing a metallic silver image.

Background

3M introduced the dual spectrum process in 1963. Although other companies marketed dual spectrum-style products, 3M was the primary manufacturer of dual spectrum copy machines and papers. The process was popular through the early 1970s and even overshadowed the Thermofax for some time. The dual spectrum process improved on the Thermofax process by making it possible to copy original written or printed material that had been made using non-metallic and carbon-based inks. However, the dual spectrum process was more complex and required two processing steps as well as an intermediate sheet to transfer the image.

Storage Environment

Cool storage (below 50 degrees) is recommended, and colder is generally better. Allowable Fluctuation: ±2°F; ±3% RH

Temp.	35–65°F (2–18°C)
RH	35–50% RH

Storage Enclosure(s)

Storage Orientation

Dual spectrum prints should be stored vertically in file folders, which are placed vertically inside acid-free storage boxes or steel filing cabinets.

Display Recommendations

If the print appears well-processed and stable, it may be displayed up to 30,000+ ft-c hours (300,000 lux hours) per year with a 1-year rest between displays.

Electrostatic Xerox Copy (Office)

Electrostatic Xerox copies. Image courtesy of Ian Batterham.

Electrostatic Xeroxed copy of a photograph — Electrostatic Xerox copy of a photograph. Image courtesy of the Chicago History Museum.

Synonyms

Photocopy
Xerographic copy
Electrophotography
Plain paper electrostatic copy

Dates

1949 – present; oversized copies from c. 1960 – present

Prevalence

Very common

Support

Plain copy paper; polyester transparency film also possible

Paper Fibers

Visible

Image/Text Tone

Monochrome (black)

Description

Electrostatic office copies like Xeroxs are nearly indistinguishable from other plain paper processes. Sometimes, the edges of the original scanned document can be seen in the electrostatic copy if not aligned exactly. Other image noise and artifacts can be picked up through subsequent copying at high contrast. The toner is made up of an inert resin and carbon black pigment. This is one of the most prevalent copy formats of the late twentieth century and at present. Photocopying is a commonly recommended, low-cost reformatting method for other at-risk documents in archival collections. Electrostatic copying and printing technology has also been implemented to produce oversized technical and architectural drawings. This application of indirect electrostatic copying began in the 1960s and persists today.

Composition

Support	Image/Text
Paper (uncoated) or polyester transparency	Black toner (carbon black pigment in resin)

Deterioration

Electrostatic Xerox copies tend to be very stable and image permanent since the toner is black carbon pigment in a resin carrier—both inert materials. Proper processing will ensure permanence but is dependent upon the quality of the paper.

Electrostatic copies should be stored at moderate temperature and relative humidity. Because the resin binders are thermoplastic polymers with low softening temperatures, avoid storage under conditions of heat and/or pressure. Experience has shown that the binder resins in xerographic copies are vulnerable to blocking to adjacent surfaces with heat or pressure. Contact with polyvinyl chloride plastic can cause softening and transfer to adjacent surfaces because of plasticizer migration from the plastic. A black Xerox copy can be expected to have good to excellent light stability, depending on the quality of the paper support.

Risk Level

Low. Store in a moderate environment. Avoid exposure to heat and pressure, in addition to polyester storage materials, as any one of them could cause toner loss and transfer to adjacent materials.

Process

Electrostatic copies are made through a five step process. First, a photoconductive selenium plate or drum is charged. The plate or drum is then exposed to a pattern of light from the original document, leaving only the image areas charged. A powdered toner is then applied over the plate or drum which only adheres to the electrostatically charged areas. The sheet of copy paper, which is given an electrical charge of opposite polarity to the plate or drum, is then brought in contact with the plate or drum thus transferring the image. The toner is fused to the paper with heat.

Background

The first commercial xerographic machines were produced by the Haloid Company (now Xerox Corporation) in 1949. The first machines were manual, with the first semi-automatic machine, the Copyflo, being released in 1955. Xerox released the first all-in-one copier, the Xerox 914, in 1959; and after that point, monochromatic electrostatic copying began to dominate the office copying market. Although additional single color toners were produced in the late 1950s, it was not until the Xerox 6500 color copier’s introduction in 1973 that full-color xerography arrived (see Color Photocopy). Since the 1960s, electrostatic copiers have remained the most popular office copying machine due to their simplicity and speed. Speaking to the prevalence of the copy process throughout the latter half of the twentieth century, Xerox'ed photographs are commonly found among paper documents.

Storage Environment

Cool storage (below 50 degrees) is recommended, and colder is generally better. Allowable Fluctuation: ±2°F; ±3% RH

Temp.	35–65°F (2–18°C)
RH	35–50% RH

Storage Enclosure(s)

Electrostatic Xerox prints should not be encapsulated or placed in polyester sleeves. Loose, unbound records should be stored in acid-free file folders. Folders should be placed in acid-free or low-lignin archival boxes. Alternatively, folders may be stored in steel filing cabinets with a baked enamel finish. Care must be taken not to overfill folders and boxes. Documents should fit easily in folders and boxes; they should not be forced into enclosures that are too small. Spacer boards, which can be created using scored and folded acid-free board, may be placed in underfilled boxes to prevent folders from slumping or bending.

Storage Orientation

Electrostatic Xerox prints should be stored vertically in file folders, which are placed vertically inside acid-free storage boxes or steel filing cabinets. If oversized, store flat (preferred) or rolled.

Display Recommendations

Light exposure during exhibition should be restricted, especially for dye-based copies and copies on zinc oxide coated paper. Electrostatic Xerox copies may be displayed up to 30,000+ ft-c hours (300,000 lux hours) per year with a 1-year rest between displays.

Color Photocopy

Various color photocopies. Image courtesy of Ian Batterham.

Synonyms

Color Xerox
Electrostatic color copy

Dates

1973 – present

Prevalence

Moderately rare

Support

Plain office copy paper or paper with polymer coating

Paper Fibers

Visible

Image/Text Tone

Color (CMYK)

Description

Cyan, magenta, and yellow toner layers may be noticeable under magnification. Like black-and-white electrostatic copies, color photocopies do not necessarily require specialized paper and can be printed on plain office copy paper. However, in order to optimize color and image clarity, papers with a polymer coating are often used for color photocopies. Polymer-coated paper may mimic photographic paper finishes, such as glossy, satin, and matte.

Composition

Support	Image/Text
Paper (uncoated or coated)	CMYK toner (inert resin, colored pigments—cyan, magenta, yellow, and black carbon pigment)

Deterioration

The preservation issues of color photocopies are largely dependent on the type of paper used. Paper with a polymer coating can be easily damaged through abrasion or flexing, and it commonly yellows. Due to the colored pigments used in CMYK toner/ink, the image will fade on light or water exposure. Xerox 6500 color copies appear to have a fairly good light stability.

Risk Level

Moderately low. Stability depends upon the ink quality, which varied greatly across manufacture lines and era.

Process

Color photocopies are produced using CMYK toners, the same process as xerography. Color photocopy machines use a drum that is reactive to the full visible spectrum. Early color copiers used multiple copy cycles, requiring multiple passes to be made for each color and using separate color filters and toners for each. Modern copiers perform a single scan to four miniature process units (CMYK) that operate simultaneously.

Background

The first electrostatic color copier was released by Xerox in 1973, although single color toner arrays were available as early as the late 1950s. Color copiers are still in use to the present day, but are very rare due to the rise of inkjet and laser color printing.

Storage Environment

Cool storage (below 50 degrees) is recommended, and colder is generally better. Allowable Fluctuation: ±2°F; ±3% RH

Temp.	35–65°F (2–18°C)
RH	35–50% RH

Storage Enclosure(s)

Electrostatic color prints should not be encapsulated or placed in polyester sleeves. Loose, unbound records should be stored in acid-free file folders. Folders should be placed in acid-free or low-lignin archival boxes. Alternatively, folders may be stored in steel filing cabinets with a baked enamel finish. Care must be taken not to overfill folders and boxes. Documents should fit easily in folders and boxes; they should not be forced into enclosures that are too small. Spacer boards, which can be created using scored and folded acid-free board, may be placed in underfilled boxes to prevent folders from slumping or bending.

Storage Orientation

Electrostatic color prints should be stored vertically in file folders, which are placed vertically inside acid-free storage boxes or steel filing cabinets.

Display Recommendations

Color pigments are sensitive to light. Use of facsimiles for display is recommended. If color photocopies are displayed, they should be exposed to no more than 5,000 ft-c hours (50,000 lux hours) per year with a 3-year rest between displays.

Laser Print (Office)

Electrostatic laser print toner noise — Laser print (electrostatic) toner offsetting and image loss due to high heat.

Laser print document. Note the absence of imaging/scanning artifacts.

Electrostatic laser print toner image surface — Laser print (electrostatic) toner surface lustre observed in raking light.

Dates

c. 1978 – present

Prevalence

Common

Support

Plain copy paper or polyester transparency film

Fibers (if paper)

Visible

Image/Text Tone

Monochrome (carbon black) or color (CMYK)

Description

Laser printing is an electrostatic printing process that is nearly identical to the xerographic copy process—the difference being that laser prints come from a digital source (i.e. printed from a computer). Unlike the electrostatic photocopying processes, there are no visual artifacts or edges of an original document visible, and the text/image is square on the page. Laser prints can be made using the same toners as plain paper electrostatic copies. Prints may be black-and-white (black toner contains resin and black carbon pigment) or color (CMYK toner containing resin and four colored pigments—cyan, magenta, yellow, and black carbon pigment). Laser printing may also be used to produce oversized technical and architectural drawings.

Composition

Support	Image/Text
Paper (uncoated) or polyester transparency	Pigment-based toner (CMYK)

Deterioration

Black-and-white laser prints tend to be very stable and permanent since the toner is essentially black carbon pigment in a resin carrier. Proper processing will ensure permanence, but is dependent upon the quality of the paper. Color laser prints may fade on light or water exposure due to the colored pigments used in CMYK toner/ink.

Risk Level

Low. Color prints are a higher preservation risk.

Process

The laser printing process is similar to electrostatic copying, but instead of copying an image from a hardcopy document, the image is transferred from an electronic file via laser. A drum is electrostatically charged with a laser that transfers the image to be printed. The charged areas of the drum picks up toner, which is then transferred to the paper and set with heat.

Background

In the late 1970s, laser printers became common for printing from mainframe computers in offices. Color laser printers and copiers emerged in the late 1980s, becoming common with desktops in the early to mid-1990s. At the same time, laser printing became economical for use with personal computers, and it had become widely used by the end of the twentieth century. The HP Laserjet printer product line is often associated with consumer-grade laser printing technology today. Along with inkjet and impact printing, laser printing is one of the three main processes accounting for all copies from electronic files at the end of the twentieth century.

Storage Environment

Cool storage (below 50 degrees) is recommended, and colder is generally better. Allowable Fluctuation: ±2°F; ±3% RH

Temp.	35–65°F (2–18°C)
RH	35–50% RH

Storage Enclosure(s)

Laser prints should not be encapsulated or placed in polyester sleeves. Loose, unbound records should be stored in acid-free file folders. Folders should be placed in acid-free or low-lignin archival boxes. Alternatively, folders may be stored in steel filing cabinets with a baked enamel finish. Care must be taken not to overfill folders and boxes. Documents should fit easily in folders and boxes; they should not be forced into enclosures that are too small. Spacer boards, which can be created using scored and folded acid-free board, may be placed in underfilled boxes to prevent folders from slumping or bending.

Storage Orientation

Laser prints should be stored vertically in file folders, which are placed vertically inside acid-free storage boxes or steel filing cabinets.

Display Recommendations

Laser prints should be exposed to no more than 5,000 ft-c hours (50,000 lux hours) per year with a 3-year rest between displays.

Copybook and Roller Copy

Iron gall ink copybook copies — Iron gall ink copybook pages. Image courtesy of the Chicago History Museum: John Kirk letter book, John Kirk collection, vol. 3, from the manuscript collection.

Copybook faint aniline ink typescript — Faded aniline ink typescript.

Synonyms

Letter book
Letterpress copybook
Pressed letter process
Glutinous ink process

Dates

1840s – 1950s

Prevalence

Common

Support

Very thin, translucent paper

Paper Fibers

Visible

Image/Text Tone

Violet, blue (aniline ink); brown (iron gall ink)

Description

Handwritten letters are most common, but letterpress copybooks also exist. Copybook copies are on thin, translucent plain paper. Image/text will be visible through both sides of the thin tissue as the ink has bled through. Image/text will appear to feather along the edge. Most inks or copy pencils colored with aniline dye will be violet or blue. Early iron-gall based inks will appear brown. Paper fibers are visible under low magnification (10x–30x). Before 1856, copies were created with iron-gall ink modified with sugars or glycerin. After 1856, glutinous aniline ink pens were widely adopted. In 1875, copy pencils colored with aniline dye, often violet or blue, were commercially introduced.

Composition

Support	Image/Text
Paper (uncoated)	Aniline, iron gall, or carbon black pigment ink

Deterioration

Although thin, most copying papers were comprised of long cotton fibers, but linen and silk were also sometimes used. These papers are relatively stable and have a low preservation risk. Less common are low-grade wood pulp papers, which were often treated with sulphuric acid to optimize translucency of the paper, leading to severe weakening or embrittlement over time. This acidity may migrate to adjacent sheets. Iron-gall ink will be prone to lacing. Aniline dyes are unstable under light and will fade easily; aniline is also water soluble.

Risk Level

High to moderate. Preservation risk depends on the composition of the ink and paper used. Low-grade wood pulp papers are susceptible to easy tearing, fragmenting, and, in combination with iron gall ink, burn-through and lacing. Higher quality cotton, linen, and silk papers are lower risk. Aniline dye-based ink is water-soluble and fades; iron gall ink corrodes and eats through paper; but, carbon black pigment is by all accounts stable.

Process

The copy was produced by placing the original letter against a water-moistened tissue, which either was bound in a copybook or was part of a copier roll that was later cut into sheets. Then, the letter would be pressed in a copying press mechanism (screw, roller, or cantilever press). Copybooks could normally only produce a single copy whereas roller copiers could produce as many as six from the original letter.

Background

Invented around 1780, the copybook did not become a popular office reprographic method until the 1840s. Copybooks of one form or another were used through the 1950s. The combination of the typewriter and carbon papers displaced copybooks.

Storage Environment

Cool storage (below 50 degrees) is recommended, and colder is generally better. Allowable Fluctuation: ±2°F; ±3% RH

Temp.	35–65°F (2–18°C)
RH	35–50% RH

Storage Enclosure(s)

Storage Orientation

Copybooks should be stored vertically in file folders, which are placed vertically inside acid-free storage boxes or steel filing cabinets.

Display Recommendations

Copybook copies contain dye- or iron-based inks which are highly light sensitive. Low-grade paper will deteriorate more rapidly if exposed to UV light. If copybook copies are displayed, they should be exposed to no more than 5,000 ft-c hours (50,000 lux hours) per year, with a 3-year rest between displays.

Diazo Print (Office)

Diazo prints in a bound volume. Note the tonal differences of the front and back sides. Image courtesy of Ian Batterham.

Diazo print recto — Diazo print. Note the yellowed edges of the paper. Taken from an image of the ILIR Library Teamsters Contracts Vertical File, 1948-69 (35/3/415) from the University Archives. Image courtesy of the University of Illinois Board of Trustees.

Diazo prints slight tonal difference between front and back sides — Diazo prints. Note the slight tonal difference between front and back sides shown here. Image courtesy of Ian Batterham.

Ozalid diazo prints — Ozalid brand diazo print. Image courtesy of Ian Batterham.

Synonyms

Diazotype
Whiteprint
Azograph
Ammonia print
Gas print
3M dry diazo
Azoflex (Ilford)
Direct print
Dyeline
Blueline; Blackline
Ozalid

Dates

1930s – present; office use, 1940s - 1970s; technical use, 1920s - 1970s

Prevalence

Moderately rare

Support

Plain or coated paper

Paper Fibers

Visible under low magnification

Image/Text Tone

Monochrome (deep blue, purple, black, or brown)

Description

The diazo print is the result of a duplication process yielding a direct positive image. The image is frequently deep blue, purple, black, or brown on a near-white ground. The ground edges often are stained yellow-brown (though not on the verso) and the paper embrittled due to oxidation and residual chemicals. Fibers will be visible under low magnification. May possess an ammonia odor and a tendency to curl if the support is thin, coated paper. Sheets will have a tendency to curl slightly. A diazo print is an azo dye image reproduction of a document or, more often, a technical line drawing (see Architectural Drawing Reproduction).

Composition

Support	Image/Text
Paper (uncoated or coated)	Azo dyes

Deterioration

Due to residual chemicals, the paper will likely be embrittled. Edges will appear yellow-brown on the recto, but not on the verso. The azo dye-based image/text may be faded, particularly if housed in an acidic enclosure/environment at any point, but also if exposed to light for an extended period. Residual chemicals and light exposure can—in tandem—cause yellowish-brown discoloration in unexposed areas. Diazo prints must be stored separately from most photographic materials due to destructive off-gassing. Alkaline storage enclosures are not advised for diazos.

Risk Level

Moderately high (older prints are at higher risk). All diazo prints should be assumed fragile and volatile. Diazos often contain residual chemicals harmful to themselves and other materials stored in proximity. They are also known to transfer color dyes to adjacent papers. Diazo prints should therefore be stored separately from other materials if possible. Alkaline storage enclosures are not advised for diazos.

Process

The various machines and processes used to create diazo prints all differ slightly but were essentially based on the same chemistry. The copy paper was coated with a sensitizing solution containing a diazo compound and a coupler compound in addition to other additives (i.e. optical brighteners). Depending on the coupler, the image/text color varied. Copies were often produced from a master made of a translucent plastic or paper material typed upon using a typewriter with special ink impermeable to UV radiation. This master was used like a photographic negative, in which light is blocked in text (dark) areas and allowed to pass through non-text (light) areas. The actual copy process was carried out using a specialized copy machine, which housed a strong UV light source and developing unit. The master and sensitized copy paper were inserted together into the copy machine and exposed to the UV light, which broke down the diazonium compounds in the copy paper. This prevented the formation of dye in the exposed areas during the development process, thus producing a positive image in the unexposed areas.

Background

While diazo prints were made as early as the 1880s, the process was not widely commercially used until the 1930s. The process was primarily used for copying large-scale drawings beginning in the 1920s. Diazo prints replaced the cyanotype (blueprint) in the engineering and architectural design spheres. The office copy application was far less common, used from the 1940s through the 1970s, primarily in Europe. Machines and papers were produced by companies such as Ilford and Ozalid.

Storage Environment

Cool storage (below 50 degrees) is recommended, and colder is generally better. Allowable Fluctuation: ±2°F; ±3% RH

Temp.	35–65°F (2–18°C)
RH	35–50% RH

Storage Enclosure(s)

Loose, unbound records should be stored in acid-free file folders. Alkaline storage enclosures are not advised for diazo prints. Folders should be placed in acid-free or low-lignin archival boxes. Alternatively, folders may be stored in steel filing cabinets with a baked enamel finish. Care must be taken not to overfill folders and boxes. Documents should fit easily in folders and boxes; they should not be forced into enclosures that are too small. Spacer boards, which can be created using scored and folded acid-free board, may be placed in underfilled boxes to prevent folders from slumping or bending.

Storage Orientation

Diazo prints should be stored vertically in file folders, which are placed vertically inside acid-free storage boxes or steel filing cabinets.

Display Recommendations

Diazo prints are highly sensitive to light. If originals are displayed, they should not be displayed for longer than 3 months at 3 ft-c maximum with a 3-year rest period between display cycles.

Thermal Print / Thermofax

Thermofax. Taken from an image of the ILIR Library Teamsters Contracts Vertical File, 1948-69 (35/3/415) from the University Archives. Image courtesy of the University of Illinois Board of Trustees.

Thermal paper receipt — Thermal print receipt with browning, a form of heat-enacted paper darkening.

Thermofax back side — Thermofax recto (front) and verso (back). Taken from an image of the ILIR Library Teamsters Contracts Vertical File, 1948-69 (35/3/415) from the University Archives. Image courtesy of the University of Illinois Board of Trustees.

Thermofax. Taken from an image of the ILIR Library Teamsters Contracts Vertical File, 1948-69 (35/3/415) from the University Archives. Image courtesy of the University of Illinois Board of Trustees.

Synonyms

Direct thermal print
3M Thermo-fax
Thermal paper
Heat transfer method
Eichner process
Ektafax

Dates

1950 – present; office use, 1950 - 1980s

Prevalence

Moderately rare in office applications, otherwise common

Support

Varies; many different colors, with or without special coating

Paper Fibers

May or may not be visible, depends on support paper

Paper Tone

Thermofax: brown; Other thermal papers may be brilliant white, beige, or yellow

Image/Text Tone

Monochrome (gray-black, red-brown, or brown-black)

Description

Due to the wide variety of patented thermography papers and formulas, the process is sometimes difficult to identify with certainty. The support paper is usually lightly sized and thin, with the backside lighter than the chemically coated, plastic-like frontside. Thermographic prints appear on a variety of support papers in many different colors, with or without special coating. Thermofax copies will have a browned recto (appearing burnt) and brilliant white verso. Other thermal paper colors include brilliant white, beige, and yellow. Most thermographic printing requires specially coated paper. Early image/text were formed with wax. Modern images are formed by leuco dyes but will also appear waxy. Image/text edges are slightly feathered and are of a lower contrast. Thermal copy text with a pin pattern is sometimes indistinguishable from impact-printed dot-matrix text. One helpful distinction is that thermally processed "ink" appears to sit on the surface of the paper, while impact-printed dot-matrix text penetrates fibers.

Composition

Support	Image/Text
Paper (specially coated)	Wax and leuco dye

Deterioration

Thermal copies deteriorate rapidly and may become embrittled. They also begin darkening and fading within five years of creation. Coated thermal papers tend to curl, and the coatings may turn brown or yellow even in dark storage. Thermofaxes will be especially brittle and stained. High relative humidity and heat will catalyze paper darkening.

Risk Level

High

Process

All thermographic processes use heat to develop copies through exposure to infra-red radiation. A temperature change in original image areas causes a chemical reaction in the copy paper that produces an image. The most common thermographic process creates a direct positive via heat transfer through image areas of the original. The specially coated copy paper contains a colorless leuco dye and an acidic color developer in a water soluble binder. As heat is applied to the copy paper, the chemicals melt together causing a chemical reaction resulting in an image. The Eichner process requires a thermocarbon sheet to be placed between the original and a plain sheet of copy paper. Heat is transferred through the dark image areas of the original, causing areas of the thermocarbon sheet to soften and transfer to the copy paper.

Background

Thermography was first marketed by the 3M Company through the introduction of the Thermofax in 1950. Thermography was initially used as a copying process, but it was short-lived due to its limitations in reproducing images from dye-based originals. Thermography was replaced in the 1980s by xerography as the office reprographic method of choice. Modern business uses for thermography include faxes, receipts, tickets, and other ad-hoc or fast print documents.

Storage Environment

Cool storage (below 50 degrees) is recommended, and colder is generally better. Allowable Fluctuation: ±2°F; ±3% RH

Temp.	35–65°F (2–18°C)
RH	35–50% RH

Storage Enclosure(s)

Storage Orientation

Thermal prints should be stored vertically in file folders, which are placed vertically inside acid-free storage boxes or steel filing cabinets.

Display Recommendations

Thermal prints of any kind should not be displayed.

Electrofax

Faded Electrofaxes — Faded electrofaxes. Image courtesy of Ian Batterham.

Faded Electrofax — Faded electrofax. Image courtesy of Ian Batterham.

Dates

1954 – 1980s

Prevalence

Fairly common

Support

Paper w/ zinc oxide coating

Paper Fibers

Not visible

Paper Tone

Light gray

Image/Text Tone

Monochrome (gray-black) or color (rare)

Description

The image/text side of the copy is coated with a shiny layer of finely divided white pigment (zinc oxide). The image/text itself is a gray-black color and of low contrast, which progressively fades further over time. The ground color of the paper is a faint gray, although sometimes it appears to have a bluish tint. From 1977 onward, the electrofax logo—a pale yellow outline of a cactus—may be on the verso.

Composition

Support	Image/Text
Paper (w/ zinc oxide coating)	Gray-black toner

Deterioration

Electrofax copies will often exhibit cracking and flaking of the zinc oxide surface coating. The image dyes used in electrofax copies will fade from light exposure and hot, humid storage environments. Sheets have a tendency to curl slightly. Migrating (copying) to a electrostatic photocopy is recommended in order to ensure long-term access to the information on electrofax copies.

Risk Level

High

Process

The electrofax was an electrostatic process. It required specially coated paper, which had a layer of finely divided material like zinc oxide on its surface. This coating was electrically charged in the dark and then exposed using a reversing lens to the image of the original document being copied. The coating lost its charge where the light struck and retained its charge in the dark (text) areas. The paper was then processed in a bath of volatile solvent containing charged dye-based toner. The charged toner would be attracted to the charged areas of the paper and form an image. The paper was then dried with heat. A dry version of the process was later developed, which used a pigment based toner applied with a brush and fused with heat.

Background

The Radio Corporation of America introduced the commercial electrofax process in 1954. The process gained some popularity and was used into the 1980s. Various office copy companies released electrofax machines, including Savin, Smith Corona Marchant (SCM), and Versatec. Versatec printers and other electrostatic copy machines were an important precursor to laser print technology. A number of electrofax machines were developed to produce images from microforms, including the RCA Bizmac (1954) and the Dial-A-Copy (1965, American Photocopy Equipment Company). Additional color toners were produced in the late 1950s but were rare. The electrofax process fell out of favor as other copy processes became more refined and created better quality, cheaper copies.

Storage Environment

Cool storage (below 50 degrees) is recommended, and colder is generally better. Allowable Fluctuation: ±2°F; ±3% RH

Temp.	35–65°F (2–18°C)
RH	35–50% RH

Storage Enclosure(s)

Storage Orientation

Electrofax prints should be stored vertically in file folders, which are placed vertically inside acid-free storage boxes or steel filing cabinets.

Display Recommendations

Electrofax documents should not be displayed.

Carbonless Copy (NCR)

Carbonless copy paper detail — Carbonless copy (NCR) paper detail.

Carbonless copy papers. Image courtesy of Ian Batterham.

Various Carbonless copy papers — Carbonless copy papers. Image courtesy of Ian Batterham.

Carbonless copy receipt detail. Courtesy of the Illinois History and Lincoln Collections, University Library, UIUC, University of Illinois Board of Trustees.

National Cash Register (NCR) logo. Image courtesy of Ian Batterham.

National Cash Register ad — National Cash Register (NCR) carbonless copy paper advertisement. This is not itself a carbonless copy. Image courtesy of Ian Batterham.

Synonyms

National Cash Register (NCR) paper
No Carbon Required (NCR)

Dates

1954 – present

Prevalence

Fairly common

Support

Specially coated paper, often a pre-printed form with spaces for information to be entered

Paper Fibers

Not visible

Image/Text Tone

Blue, purple, gray, green, yellow

Description

Carbonless copies tend to be used for data entry on pre-printed forms that have different copy layers on different colored papers. It usually is made up of a top sheet (on which the user writes with a ballpoint pen or stylus) with one or more sheets below onto which the image/text is duplicated. The top layer is often white, with the copy-paper layers various colors including yellow, blue, or green. The image/text on a carbonless copy is the result of a chemical reaction between colorless leuco dye precursor and the acidic layer on top of the copy paper. Blue-purple is a very common image/text color. The National Cash Register (NCR) logo may be present on the form.

Composition

Support	Image/Text
Paper w/ chemical coating	Leuco dye

Deterioration

Yellowing and embrittlement is common due to the acidic coating. Image fading is extreme due to dye-based ink, and complete image loss can occur in a few years’ time.

Risk Level

Moderately high. Copies should be made to preserve content before image becomes faded and illegible.

Process

The top sheet is coated on the back with a layer of microcapsules containing dye precursor. With the application of pressure (i.e. from the tip of a pen), these microcapsules burst and react with the acidic layer on the copy sheets, forming a colored image.

Background

Carbonless copy papers were introduced by the National Cash Register Company in 1954 in the US; this is why carbonless paper is often referred to and marked as "NCR." The paper was designed specifically for ephemeral purposes, such as creating tickets and receipts. Carbonless paper continues to be used in some corners of the world today despite the known health hazards associated with it.

Storage Environment

Cool storage (below 50 degrees) is recommended, and colder is generally better. Allowable Fluctuation: ±2°F; ±3% RH

Temp.	35–65°F (2–18°C)
RH	35–50% RH

Storage Enclosure(s)

Storage Orientation

Carbonless copies should be stored vertically in file folders, which are placed vertically inside acid-free storage boxes or steel filing cabinets.

Display Recommendations

Carbonless copies are highly light sensitive and should not be displayed.

Inkjet Print (Office)

inkjet copy — Inkjet copy with text and image from zine. Image courtesy of Leila Ammar, www.daliahammar.com.

Dates

1984 – present

Prevalence

Common

Support

Varies; may be plain uncoated paper, or paper with a waxy or glossy coating (coating substance varies)

Paper Fibers

Visibility varies by paper manufacture

Image/Text Tone

Monochrome or color (CMYK); dye- or pigment-based

Description

In cases of black-and-white text copy, the paper is often plain uncoated copy paper. Color images will likely be printed on bright white paper, which is often produced to mimic photo paper with glossy or matte surfaces and a polymeric feel. Depending on the type of paper used, inkjet prints may be made with a variety of CMYK dyes and pigments. Inkjet images are composed of very tiny cyan, magenta, yellow, and black dots in any number of patterns. See Inkjet Print for additional information about inkjet inks and papers.

Inkjet is also fairly common as a modern printing process for architectural layouts rendered on with computer software (e.g. CAD). These layouts are large-scale line vector graphics that are often printed on paper but can sometimes be printed on either polyester film or vellum paper.

Composition

Support	Image/Text
Paper (with or without resin-coated layers)	Pigment- or dye-based ink (CMYK)

Deterioration

Stability will vary depending on the ink. Inkjet prints made with dye-based inks are water soluble and highly susceptible to color bleeding or running if exposed to water. If printed with pigment-based inks, the color is less likely to bleed if exposed to water. Color images will fade if exposed to light, high temperature, and/or humidity. This is particularly the case for magenta dye. All inkjet prints should be protected from humidity and prolonged exposure to light, but neutral B&W prints will discolor more quickly and fade to a yellowish-brown color. This is because monochrome images are produced through a composite of at least four layers of dots, each a different color ink, so when one color begins to fade, it alters the tone of the entire image.

Risk Level

Moderate. Inkjet prints are prone to yellowing and staining, especially if exposed to high humidity, intense light, or atmospheric pollutants like ozone. Ink bleeding may occur if exposed to high humidity or moisture. The preservation risks of inkjet prints greatly depend on the quality of paper and type of ink used. Pigment-based inks are considerably more stable than dye-based.

Process

Inkjet printing processes can be split into two common types: continuous pressure and drop formation (Continuous Ink Jet, or CIJ) and intermittent drop formation (Drop on Demand, or DOD). CIJ printers are usually used for high-end printing, while DOD printers are cheaper and more widely used in homes and offices. The most common type of DOD printers are bubble jet printers. Heat is applied to the ink, which forms a tiny bubble. The ink is propelled onto the paper’s surface by the force of the bubble bursting, resulting in the characteristic series of very small, random dots that make up an inkjet print image.

Background

Although the technology behind it was developed in the 1950s, the inkjet printing process was not widely used for home or office printing until the mid-1980s. The first commercially sold inkjet printer was released in 1984 by Hewlett-Packard. Inkjet printers filled the need for a cheap and simple printer, and they gained great popularity for both home use and business purposes over the 1990s. Inkjet printers remain popular to the present day. Along with laser and impact printing, inkjet printing is one of the three main processes accounting for all copies from digital files at the end of the twentieth century. Since the 2000s, inkjet has stood as the preferred printing method for computer-assisted drawings (CAD).

Storage Environment

Cool storage (below 50 degrees) is recommended, and colder is generally better. Allowable Fluctuation: ±2°F; ±3% RH

	Ideal
Temp.
RH	30-50% RH

Storage Enclosure(s)

Storage Orientation

Inkjet prints should be stored vertically in file folders, which are placed vertically inside acid-free storage boxes or steel filing cabinets.

Display Recommendations

Inkjet prints should be exposed to no more than 5,000 ft-c hours (50,000 lux hours) per year with a 3-year rest between displays.

Resources

ISO. (2007). 18916 Imaging Materials: Processed imaging materials–Photographic activity test for enclosure materials. Geneva, Switzerland: International Organization for Standardization.
Nadeau, L. (1994). Encyclopedia of printing, photographic, and photomechanical processes: Containing invaluable information on over 1500 processes. Fredericton, NB, Canada: Atelier L. Nadeau.
Rhodes, B.J. & Streeter, W.W. (1999). Before photocopying: The art and history of mechanical copying, 1780-1938. New Castle, DE: Oak Knoll Press.
For additional resources, see Office Reprographics.

Office Printing and Reprography

Office Printing and Reprographic Processes

"Ink" on Paper

Dye-Ink Transfer

Photographic

Electrostatic

Other Processes

Carbon Copy

Stencil Copy

Typography

Offset Lithography (Office)

Impact Print

Hectograph Copy (Office)

Spirit Duplicate

Photostat Copy (Office)

Diffusion Transfer

Dual Spectrum

Electrostatic Xerox Copy (Office)

Color Photocopy

Laser Print (Office)

Copybook and Roller Copy

Diazo Print (Office)

Thermal Print / Thermofax

Electrofax

Carbonless Copy (NCR)

Inkjet Print (Office)

Resources