-
Collection ID Guide
- Architectural Drawing Reproduction
Architectural Drawing Reproduction
Architectural and engineering prints have been produced by both
photo-reproductive and photomechanical methods. Before the 1870s,
architectural and technical drawing copies were produced by hand using
translucent tracing paper or drafting cloth. Blueprinting was introduced
to North American architectural and engineering professions in the
mid-1870s and quickly gained popularity. Many new photo-reproductive
processes followed using a variety of light sensitive materials, paper
and cloth supports, and processing methods. Many of the processes that
were utilized for striking prints from drawings were also used in other
commercial applications (e.g. office reprographics).
A majority of
architectural drawings and their copies are "oversize," that is, large
enough that they exceed average storage spaces. The source of oversize
papers' problems is their unwieldiness, which makes them susceptible to
damage through handling and subpar storage. Oversized materials are
often found folded or rolled but are ideally stored in flat file
cabinets.
- Dates found on prints may be misleading. Unless the date is
hand-written or stamped directly on the print, it is quite possible that
the date the print was created does not coincide with the date found on
the print: the date found on the print may instead reflect when the
original drawing was produced.
- The most common support materials for paper-based prints are
muslin cloth (nineteenth–early twentieth century), cardboard, fiberboard
(Masonite), and foam-core.
- If format identification is unsuccessful, you may select
"Unidentified" to perform a more generalized PSAP assessment of the
architectural drawing reproduction.
Photoreproductive Processes
Photomechanical Processes (Ink or toner on paper)
Related Notes
Ferro-Gallic Print
- Synonyms
-
- Iron gall print
- Black-line process
- Dates
- 1859 – 1930s
- Prevalence
- Rare
- Support
- Paper, occasionally drafting cloth
- Fibers (paper, cloth)
- Visible under low magnification
- Ground Color
- Light, usually white (likely yellowed or discolored)
- Image/Lines
- Monochrome (blue-black with metallic sheen, which may have faded to brown or dull black)
- Description
- Ferro-gallic prints are always positive images--dark lines on a
light-colored ground. Although the lines were dark blue-black at the
time of their creation, they are usually found faded to brown or dull
black. Paper fibers are visible under low magnification. Depending upon
the method of production, the image lines under magnification may either
appear raised or burned into the paper surface. Ferro-gallic prints
were conventionally used as studies or process prints, and they may have
additional media and marginalia.
- Composition
-
Support |
Image/Text |
Paper or drafting cloth |
Iron gallo-tannate pigment |
- Deterioration
- Ferro-gallic prints are unstable. Due to the presence of acid
remaining in the support after processing, the support is likely to be
brittle and yellowed. The lines of ferro-gallic prints are made up of
ferric gallotannate, which is also acidic and may cause lacing of the
paper support. Ferro-gallic prints are sensitive to light, and image
lines may become brown, fade, or disappear completely. They should not
be stored in contact with other prints, as the acidic prints may damage
adjacent objects.
- Risk Level
- Moderately high. Ferro-gallic prints are highly acidic,
frequently brittle, and very sensitive to light. Like iron gall ink, the
image material is acidic and may degrade the paper support to the point
of eating through it. Store in the dark in unsealed, unbuffered, and pH
neutral enclosures or dividers. Keep them away from other collection
materials so to curb the negative effects of acidic off-gassing.
- Process
- Ferro-gallic prints may be sensitized in one of two ways. Prior
to 1900, the support was simply coated with a gum arabic or gelatin
solution containing ferric salts. After 1900, the acidic developer was
incorporated into the ferric salt-and-gelatin solution. Despite this
difference, the process remained the same. The sensitized paper is then
placed beneath a translucent master document or drawing and exposed to
strong UV light: the master is used like a photographic negative, in
which light is blocked in dark areas (e.g. lines/text) and allowed to
pass through translucent spaces. As light exposes the ferric salts, the
gelatin (or gum arabic) in these unblocked areas become water soluble.
The paper is then washed in water in order to release the acidic
developer and turn the ferric salts into a ferric gallotannate pigment,
while removing the gelatin (or gum arabic) and residual ferric salts.
The resulting image is qualitatively and nearly chemically the same as
iron gall ink.
- Background
- The ferro-gallic process was originally developed by Alphonse
Louis Poitevin in 1859 and was mostly used in Europe. It was phased out
in the 1930s in favor of cheaper and more practical processes, such as
the diazo print. Despite being more expensive and difficult than
blueprinting, ferro-gallic prints were useful for producing clean copies
of tracings, since the process allowed for corrections to be made
during processing. Additionally, the ferro-gallic process produces the
most ink-like lines of technical/architectural drawing reproduction
processes, thereby allowing the production of imitation ink drawing
multiples, which proved valuable for technical drawings.
- Storage Environment
-
Cool storage (below 50 degrees) is recommended. Allowable Fluctuation: ±2°F; ±3% RH
|
Ideal |
Temp. |
35–65°F (2–18°C) |
RH |
35–50% RH |
Based on NISO TR01-1995
- Storage Enclosure(s)
-
Technical prints were generally not made with long-term
stability in mind; most were created quickly and cheaply to serve an
ephemeral, utilitarian purpose. As a result, many technical prints may
retain chemical residues from processing. These residual chemicals may
off-gas or cause damage if placed in contact with other prints.
Prints are usually large, and they are best stored horizontally
in flat files, preferably those made of enameled steel, stainless
steel, or anodized aluminum. Store different types of architectural
prints separately in order to prevent contact degradation. Alkaline
storage enclosures are not advised for ferro-gallic prints. Folders cut
to drawer size are recommended, with less than 12 prints to a folder and
with interleaving sheets placed between them (both neutral pH).
Individual prints should be stored in polyester sleeves within folders
in order to both protect particularly fragile items and separate formats
from one another. Polyester sleeves also provide additional support
during handling.
It may be acceptable to store the prints rolled if space for
flat storage is not available, but brittle or otherwise fragile prints
should not be rolled. Prints that are strong and flexible enough to be
rolled must have an interior support: a neutral pH cardboard tube (over
3" diameter) itself wrapped in polyester or neutral paper. The rolled
print and interior support may be wrapped in the neutral paper or
polyester, and they should be stored horizontally, not upright. Prints
should not be folded, since this will create fold lines that weaken the
paper and cause it to tear. All storage materials should pass the
Photographic Activity Test (PAT) as specified in ISO Standard
18916:2007.
- Storage Orientation
- Flat (preferred) or rolled.
- 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 items in cases should
be securely framed or matted using preservation-quality materials that
have passed the Photographic Activity Test (ISO 18916:2007).
Ferro-gallic prints should not be exhibited because they are
extremely sensitive to light and are often brittle. Consider the use of
facsimiles in place of original documents.
Aniline Print
- Synonyms
-
- Green print
- Chrome process
- Endemann’s process
- Vanadium process
- Flexography
- Dates
- 1864 – 1890s
- Prevalence
- Rare
- Support
- Paper or drafting cloth
- Fibers (paper, cloth)
- Visible
- Ground Color
- Greenish or yellowish tint
- Image/Lines
- Monochrome (violet, blue, or black; other colors possible, but rare)
- Description
- Aniline prints are always positive images. The image ground may
be slightly flecked but is overall a slight greenish or yellow-beige
tint. The green of the ground is the sensitized coating on the paper.
The verso (back) will be lighter than the color of the support material.
Like other aniline dye processes, the image or text is of low-contrast
with soft lines. Image lines also appear to be deeply embedded within
the support when viewed under magnification. The print may include
additional coloring achieved through watercolor. Aniline prints resemble
diazo prints but predate them by about 25 to 50 years.
- Composition
-
Support |
Image/Text |
Paper or drafting cloth |
Aniline dye ink |
- Deterioration
- Aniline images will fade on exposure to light. The surface may
exhibit white scratches, scuffs, and cracks, due to residual acids in
the print. Resulting from the presence of residual (and frequently
acidic) chemicals, paper supports will often be left brittle while cloth
supports will become limp.
- Risk Level
- Moderate. UV light exposure is the primary risk to aniline
prints by causing severe image fading. High temperature and high
humidity will accelerate print deterioration. Residual chemicals will
exacerbate breakdown and will cause structural degradation and
yellowing. Due to the acidic nature of aniline prints, they should be
segregated from other collection materials and stored in pH neutral
enclosures.
- Process
- A support is sensitized by floating one side in an aniline
chemical compound solution containing chromic salts before it is set to
dry in a dark environment. This sensitized support is then placed under a
translucent master document or drawing and exposed to strong UV light.
The master is used like a photographic negative, in which light is
blocked in dark areas (e.g. lines/text) and allowed to pass through
translucent spaces. The image is then developed through the copy’s
exposure to aniline fumes, which produces a positive image when it
interacts with the chromic salts. The aniline print is then rinsed in an
acidic bath to remove excess compounds.
- Background
- Introduced as a drawing and writing reprographic process in
1864, aniline prints rose in public favor quickly due to its relatively
fast drying ink. Alongside the hectographic process, aniline printing
was one of the most common processes for technical/architectural drawing
reproductions before being supplanted by the blueprint at the end of
the nineteenth century. A derivative aniline process branded as
"flexography" was adopted in the 1940s for printing flexible product
packaging.
- Storage Environment
-
Cool storage (below 50 degrees) is recommended. Allowable Fluctuation: ±2°F; ±3% RH
|
Ideal |
Temp. |
35–65°F (2–18°C) |
RH |
35–50% RH |
Based on NISO TR01-1995
- Storage Enclosure(s)
-
Technical prints were generally not made with long-term
stability in mind; most were created quickly and cheaply to serve an
ephemeral, utilitarian purpose. As a result, many technical prints may
retain chemical residues from processing. These residual chemicals may
off-gas or cause damage if placed in contact with other prints.
Prints are usually large, and they are best stored horizontally
in flat files, preferably those made of enameled steel, stainless
steel, or anodized aluminum. Store different types of technical prints
separately in order to prevent contact degradation. Alkaline storage
enclosures are not advised for aniline prints due to the pH sensitivity
of aniline dye. Folders cut to drawer size are recommended, with less
than 12 prints to a folder and with interleaving sheets placed between
them (both neutral pH). Individual prints may be stored in polyester
sleeves within folders in order to protect particularly fragile items or
to separate formats from one another. Polyester sleeves also provide
additional support during handling.
It may be acceptable to store the prints rolled if space for
flat storage is not available, but brittle or otherwise fragile prints
should not be rolled. Prints that are strong and flexible enough to be
rolled must have an interior support: a neutral pH cardboard tube (over
3" diameter) itself wrapped in polyester or neutral paper. The rolled
print and interior support may be wrapped in the neutral paper or
polyester, and they should be stored horizontally, not upright. Prints
should not be folded, since this will create fold lines that weaken the
paper and cause it to tear. All storage materials should pass the
Photographic Activity Test (PAT) as specified in ISO Standard
18916:2007.
- Storage Orientation
- Flat (preferred) or rolled.
- 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 items securely framed
or matted using preservation-quality materials that have passed the
Photographic Activity Test (ISO 18916:2007).
Aniline dyes are highly sensitive to light, and they should not
be exposed to more than 5,000 ft-c hours (50,000 lux hours) per year
with a 3-year rest between displays.
Blueprint
- Synonyms - Blueprint
-
- Cyanotype
- Ferro-prussiate print
- Synonyms - Positive Blueprint
-
- Pellet print
- Cyanotype positive
- Cyanofer
- Positive ferrotype
- Dates
- c. 1872 - present; technical uses, c. 1872 - 1950s
- Prevalence
- Common
- Support
- Paper or drafting cloth
- Fibers (paper, cloth)
- Visible
- Ground Color
- Prussian blue (negative print); white (positive print)
- Image/Lines
- Monochrome (white on negative print; blue on positive print)
- Description
- A blueprint is a single-layer print comprised of a blue pigment
embedded in an uncoated paper or cloth fibers. The ground color is a
brilliant "Prussian" blue with continuous tone. The fibers of the cloth
or paper will be clearly visible and likely will be rough. The surface
finish is extremely matte with no surface gloss due to the absence of a
binder layer. Most blueprints are negatives (white image/text lines on a
dark blue background), but sometimes positive images were also created
to allow for easier reading. These positive prints (dark blue lines on a
light ground) were known as pellet prints. The verso (back) of either
type of print will likely be white, off-white, or the color of the
support paper or cloth.
- Composition
-
Support |
Image/Text |
Paper or drafting cloth |
Blue pigment |
- Deterioration
- Blueprints are very sensitive to light but are otherwise quite
stable if kept in dark storage. Faded blueprints may regain substantial
image density when kept in dark storage. Paper distortion is a common
quality that results from the blueprint wet process. Some slight overall
unevenness of the paper is not necessarily a deteriorative trait.
- Risk Level
- Moderately low. Blueprints are relatively stable and image
permanent if kept in dark storage conditions and out of an alkaline pH
environment. The integrity of the support paper is often the decisive
factor in the long term preservation of blueprints.
- Process
- A sheet of heavy paper or cloth, which has first been sensitized
with ferric ammonium citrate and potassium ferricyanide, is exposed
through an overlaid drawing to sunlight or another UV light source.
Wherever the light strikes the sensitized support, the ferric salts
become ferrous salts. The support is immersed in a water bath after
exposure, and a chemical reaction between the water and ferrous salts
produces the Prussian blue pigment (ferric ferrocyanide). The ferric
salts remaining in the unexposed areas are then washed away. This
results in the white lines that create the image. The main difference in
the process of the creating a pellet print was the addition of a
colloid (e.g. dextrin, gum arabic, or gelatin) on the surface of the
sensitized cloth or paper support.
- Background
- The term "blueprint" generally refers to line drawings
reproduced by the cyanotype process for schematic or technical drawings.
Blueprints/cyanotypes were most commonly produced between the 1870s
and 1930s, but they are still made today. The cyanotype process was
invented in the eighteenth century but did not attract much further
development until John Frederick William Herschel's paper on the format
in 1842. However, the process was still not widely adopted until the
1870s. The first commercial cyanotype paper was developed in France in
1872; the first commercial cyanotype producting machine was introduced
to the United States in 1875. Pre-sensitized papers became available in
1876 from the Marion Company of Paris and were sold worldwide, including
in the United States. Due to its affordability and simple processing,
blueprints/cyanotypes were typically produced in-house by amateur
photographers for the purpose of reproducing engineering and
architectural designs. Beginning in the 1920s, machines were developed
to produce complete prints from start to finish. During the 1930s,
blueprinting began to lose its popularity due to the development of the
diazo process, which used vapor to develop the image rather than
immersion in a liquid bath. This was particularly important for
technical prints in which dimensional changes could occur with the
introduction of moisture. Thus, using a "dry" process was preferable in
order to preserve the original scale of the drawing. The popularity of
cyanotypes for non-technical uses underwent a revival in the 1960s. The
blueprint/cyanotype process was widely used before the 1930s, and it
represents one of the most widely held types of technical prints in
collections.
- Storage Environment
-
Cool storage (below 50 degrees) is recommended, and colder is
better unless frequently used (frequent and sudden changes in
temperature and relative humidity could result in physical stress to the
object). Allowable Fluctuation: ±5°F; ±5% RH
|
Ideal |
Temp. |
32–40°F (0–4°C) |
RH |
30–40% RH |
- Storage Enclosure(s)
-
Technical prints were generally not made with long-term
stability in mind; most were created quickly and cheaply to serve an
ephemeral, utilitarian purpose. Many of these prints will retain
chemical residues from processing. These residual chemicals may off-gas
or cause damage if placed in contact with other prints.
Blueprints/cyanotypes should be stored in alkaline-free paper
products in order to prevent fading of the blue pigment. Buffered paper
should be avoided. Prints are usually large, and they are best stored
horizontally in flat files, preferably those made of enameled steel,
stainless steel, or anodized aluminum. Store different types of
technical prints separately in order to prevent contact degradation.
Folders cut to drawer size are recommended, with less than 12 prints to a
folder and with interleaving sheets placed between them. Individual
prints may be stored in polyester sleeves within folders in order to
protect particularly fragile items or to separate formats from one
another. Polyester sleeves also provide additional support during
handling.
It may be acceptable to store the prints rolled if space for
flat storage is not available, but brittle or otherwise fragile prints
should not be rolled. Prints that are strong and flexible enough to be
rolled must have an interior support: a neutral pH cardboard tube (over
3" diameter) should be wrapped in polyester or neutral paper. The rolled
print and interior support may be wrapped in the neutral paper or
polyester, and they should be stored horizontally, not upright. Prints
should not be folded, since this will create fold lines that stress the
paper fibers and cause it to tear. All storage materials should pass the
Photographic Activity Test (PAT) as specified in ISO Standard
18916:2007.
- Storage Orientation
- Flat (preferred) or rolled.
- 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. Items in cases should be
securely framed or matted using preservation-quality materials that have
passed the Photographic Activity Test (ISO 18916:2007).
If cyanotypes are displayed, it should be for no longer than 3
months at 3 ft-c maximum with a 3-year rest period between display
cycles.
VanDyke Print
- Synonyms
-
- Brownprint
- Brownline
- Solar paper print
- Silver paper print
- Sepia process
- Maduro
- Dates
- c. 1890 – early 1960s
- Prevalence
- Fairly common
- Support
- Paper, usually light- or medium-weight
- Fibers (paper)
- Visible in highlights
- Ground Color
- Brown (negative print); white (positive print)
- Image/Lines
- Monochrome (white on negative print; brown on positive print)
- Description
- VanDyke prints may be found as either a positive or negative
image on a paper support. In either case, the brown of the image will
exhibit a slightly cool, metallic quality when viewed under light. The
brown image material will appear to be embedded into the fibers of the
paper support. Negative VanDyke prints (white lines on a brown ground)
were typically created as an internegative and used in service of
creating a final blueprint or a positive VanDyke. Positive VanDyke
prints (brown lines on a white ground) often resemble sepia diazo
prints, but the uniformity of the positive VanDyke’s "white" paper
ground sets it apart from the speckled, "dirty" ground of a sepia diazo.
The brown lines of a VanDyke print are also generally cooler in tone
than those of a sepia diazo. VanDyke prints are generally high contrast.
Blue staining on the verso (back) is the result of residual iron salts.
- Composition
-
Support |
Image/Text |
Paper |
Silver and iron deposits |
- Deterioration
- Residual chemicals from image processing may cause the image to
yellow and support to weaken. VanDyke prints are prone to silvering and
may yellow significantly, especially if they were not properly washed
during processing. Deterioration characteristics and handling
recommendations are on the whole similar to those for silver gelatin
prints, photostats, and other silver-based photographic processes.
- Risk Level
- Moderate. Exposure to air pollutants is a significant threat to
silver images, and warm, humid environments will accelerate these
destructive effects. Due to the residual chemicals in VanDyke prints and
their sensitivity to airborne pollutants, it is recommended that they
be stored in polyester sleeves.
- Process
- A negative VanDyke was typically created as an internegative and
was used in the service of creating a final blueprint or positive
VanDyke print. The production process for creating VanDyke prints is
similar to that used for the production of blueprints, with the addition
of a fixing bath. The support paper is first coated with a sensitizing
solution comprised of silver salts, iron salts, and an organic acid.
After this coating is dried, the paper is placed in direct contact with
an original drawing or intermediate negative and exposed to light. The
ferric salts are chemically altered when exposed to light. The exposed
print is rinsed in water in order to release the organic acid in the
coating. This acidity creates a reaction between the iron and silver and
produces a brown color in the exposed areas. The unexposed ferric salts
remain water soluble and are washed away, leaving the support paper
visible. The print is placed in a fixing bath, rinsed a final time, and
then dried.
- Background
- The process used to create VanDyke prints was patented by H.
Shawcross, first in Paris in 1889 and then three years later in England.
The process is named, however, after a man with the surname Vandyke,
who patented a similar process in 1901. VanDyke prints were produced
beginning in the 1890s through the early 1960s. As with other wet
processes, the VanDyke process was phased out by the increasing use of
diazo prints. Diazo prints became preferred because their dry processing
eliminated any concern for dimensional variations, which were caused by
the introduction of moisture. VanDyke prints were typically used as
internegatives, whose final product was either a positive blueprint or
positive VanDyke print. The process was useful for reproducing damaged
originals and very faint images like pencil drawings.
- Storage Environment
-
Cool storage (below 50 degrees) is recommended. Allowable Fluctuation: ±2°F; ±3% RH
|
Ideal |
Temp. |
35–65°F (2–18°C) |
RH |
35–50% RH |
Based on NISO TR01-1995
- Storage Enclosure(s)
-
Technical prints were generally not made with long-term
stability in mind; most were created quickly and cheaply to serve an
ephemeral, utilitarian purpose. As a result, many of these prints may
retain chemical residues from processing. These residual chemicals may
off-gas or cause damage if placed in contact with other prints. Always
segregate VanDykes from diazo prints, which contain the silver-bleaching
chemical thiourea.
Prints are usually large, and they are best stored horizontally
in flat files, preferably those made of enameled steel, stainless
steel, or anodized aluminum. Store different types of architectural
prints separately in order to prevent contact degradation. Folders cut
to drawer size are recommended, with less than 12 prints to a folder and
with interleaving sheets placed between them (both alkaline or neutral
pH). Individual prints should be stored in polyester sleeves within
folders in order to both protect particularly fragile items and separate
formats from one another. Polyester sleeves also provide additional
support during handling.
It may be acceptable to store the prints rolled if space for
flat storage is not available, but brittle or otherwise fragile prints
should not be rolled. Prints that are strong and flexible enough to be
rolled must have an interior support: a neutral pH cardboard tube (over
3" diameter) itself wrapped in polyester or neutral paper. The rolled
print and interior support may be wrapped in the neutral paper or
polyester, and they should be stored horizontally, not upright. Prints
should not be folded, since this will create fold lines that weaken the
paper and cause it to tear. All storage materials should pass the
Photographic Activity Test (PAT) as specified in ISO Standard
18916:2007.
- Storage Orientation
- Flat (preferred) or rolled. Always segregate VanDykes from diazos, which contain the silver-bleaching chemical thiourea.
- Display Recommendations
-
Responsible display practices ensure the long-term preservation
of collections. Facsimiles should be used whenever possible. 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 items securely framed
or matted using preservation-quality materials which have passed the
Photographic Activity Test (ISO 18916:2007).
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.
Photostat (Architecture)
- Synonyms
-
- Photostatic print
- Rectigraph
- Stat
- Dates
- 1909 – c. 1980, use declines after 1950
- Prevalence
- Fairly common
- Support
- Sensitized photographic paper (medium-weight), drafting cloth, vellum paper
- Fibers (paper, cloth)
- Visible in highlights
- Ground Color
- Black (negative); white (positive)
- Image/Lines
- Monochrome (white on negative print; black on positive print)
- Description
- The image may be negative or positive, although negatives (i.e.
white image/text on black background) are more common. The image/text is
comprised of silver particles, as in silver gelatin DOP prints. Copies
are similar to silver gelatin black and white photographs, including the
tendency to exhibit silver mirroring. The image may be either
high-contrast black and white or, if produced from a color or
pencil-drawn original, black and white with shades of gray. The paper is
thinner than most photographic paper as it lacks a baryta layer and has
thinner emulsion. The largest possible print size was 8 ½" × 11" until
the 1920s, when prints began to be made up to 18" × 24". Final prints as
large as 40" × 60" could be produced by commercial photo labs
specializing in architectural and engineering drawings.
- Composition
-
Support |
Binder/Emulsion |
Image/Text |
Paper, drafting cloth, or vellum paper |
Gelatin |
Silver |
- Deterioration
-
Preservation of photostatic prints is nearly identical to the
preservation properties of silver gelatin DOP prints. Photostatic prints
are prone to silvering and may yellow significantly, especially if they
were not properly washed. For more information, see Photographic Prints.
- Risk Level
- Moderately low. Exposure to air pollutants is often the
significant prolonged threat to silver image materials, but warm and
humid environments will also accelerate the destructive effects.
- Process
- Photostat copy machines were basically large cameras that used a
prism to produce a right-reading image. Each exposure produced one
print, which was usually a negative. In 1953, Kodak released a
direct-positive process that allowed 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 image. After exposure, the paper was placed in a developing
bath beneath the camera and then into a fixer bath. Processing was
completed in darkroom conditions. The print was then washed in water,
with the excess water removed by squeegee after taking the print out of
the final bath. The print was finally dried by one of three procedures:
pressing between blotters, passing through a set of heated rollers, or
drying face-down on glass (in order to create a glossy finish).
- Background
- The first commercially produced photostatic copy machine was the
rectigraph, which was first manufactured in Rochester, NY in 1909.
Photostat prints of architectural drawings became more common after
1920, when larger print sizes became available. By 1936, photostat
papers were available in a range of grades and finishes. Sensitized
fabric (e.g. Sensitex) could also be used in place of paper. Although
Eastman Kodak Company introduced a direct-positive process in 1953, the
popularity of photostatic copying declined over the next several
decades.
- Storage Environment
-
Cool storage (below 50 degrees) is recommended. Allowable Fluctuation: ±2°F; ±3% RH
|
Ideal |
Temp. |
35–65°F (2–18°C) |
RH |
35–50% RH |
Based on NISO TR01-1995
- Storage Enclosure(s)
-
Technical prints were generally not made with long-term
stability in mind; most were created quickly and cheaply to serve an
ephemeral, utilitarian purpose. As a result, many technical prints may
retain chemical residues from processing. These residual chemicals may
off-gas or cause damage if placed in contact with other prints.
Prints are usually large, and they are best stored horizontally
in flat files, preferably those made of enameled steel, stainless
steel, or anodized aluminum. Store different types of architectural
prints separately in order to prevent contact degradation. Acid-free (pH
7.2-9.5) enclosures and/or folders strongly advised. Folders cut to
drawer size are recommended, with less than 12 prints to a folder and
with interleaving sheets placed between them. Individual prints may be
stored in polyester sleeves within folders in order either to protect
particularly fragile items or to separate formats from one another.
Polyester sleeves also provide additional support during handling.
It may be acceptable to store the prints rolled if space for
flat storage is not available, but brittle or otherwise fragile prints
should not be rolled. Prints that are strong and flexible enough to be
rolled must have an interior support: a neutral pH cardboard tube (over
3" diameter) itself wrapped in polyester or neutral paper. The rolled
print and interior support may be wrapped in the neutral paper or
polyester, and they should be stored horizontally, not upright. Prints
should not be folded, since this will create fold lines that weaken the
paper and cause it to tear. All storage materials should pass the
Photographic Activity Test (PAT) as specified in ISO Standard
18916:2007.
- Storage Orientation
- Flat (preferred) or rolled.
- 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 items in cases should
be securely framed or matted using preservation-quality materials that
have passed the Photographic Activity Test (ISO 18916:2007).
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. However, photostat prints were often
poorly processed, so a more conservative approach to display may be
required (e.g. 5,000 ft-c hours [50,000 lux hours] per year with a
3-year rest between displays).
Wash-Off Print
- Synonyms
-
- CB print; "See-Bee" print
- Dupro process
- Photoprint
- Photo-litho
- Thermoline Wash-Off Film
- Dates
- 1920s – present
- Prevalence
- Fairly common
- Support
- Drafting cloth (pre-1950), vellum paper, or polyester (post-1950)
- Ground Color
- Light, usually white (may be discolored)
- Image/Lines
- Black
- Description
- Wash-off prints are always positive images. The image may be
printed in reverse. The image lines or text are strong, black, and
ink-like, and they appear to sit on the surface of the support in slight
relief. Due to these qualities, wash-off prints are often mistaken for
original ink drawings. A metallic sheen may also be observed in the
image material. While the image is high contrast and the ground is
generally clean and smooth, sometimes tiny black flecks left over from
the emulsion may be littered across the whitespace. Early support
materials were frequently glossy, medium-weight tracing cloth; prints
were also made on vellum tracing paper and polyester (Mylar) by the
1950s. If on cloth, the ground may be slightly discolored or stained.
Images were often printed in reverse to be used as reproducibles.
- Composition
-
Support |
Binder/Emulsion |
Image/Text |
Drafting cloth, vellum paper, polyester |
Gelatin |
Silver |
- Deterioration
-
Preservation factors of a wash-off print are similar to those of a
silver gelatin print. Wash-off prints may become oxidized causing the
black image to turn warm brown or yellow. The black lines may also
exhibit silver mirroring. Drafting cloth support (and ground) may
discolor or stain over time. Prints made on plastic support may become
brittle or yellowed depending on the type of plastic. Most documentation
suggests polyester supports were used to make wash-off prints, which
will not exhibit these deteriorative characteristics. For related
information, see Photographic Prints.
- Risk Level
- Moderate. Exposure to air pollutants is a significant threat to
silver images, and warm, humid environments will accelerate destructive
effects. Although the full array of plastic support materials used is
not definitively known, polyester film was the primary plastic base and
will therefore be relatively stable. Regardless of the support material,
high temperatures and high humid environments should be avoided.
- Process
- Wash-off prints were produced using a Vandyke negative as the
intermediate image. The VanDyke negative itself was produced via contact
printing from the original tracing. The final support material was
sensitized with a silver halide sensitizing agent and an alkaline
activated developer in a gelatin emulsion. The sensitized support was
then exposed under the Vandyke negative, causing the exposed areas to
become insoluble. The non-image areas were then washed away in water,
and the print was immersed in a highly alkaline activating solution that
then developed and hardened the image. A final bath removed the
developer. At this point, the image could be altered by wiping the
surface with cotton or a camel hair brush. Some manufacturers
recommended that the final wash be followed by an additional fixer bath
to further harden the image. The image was then hung to dry.
- Background
- One of the earliest silver-based processes used for drawing
duplication, the wash-off process was developed in the early 1920s. Two
companies claimed credit for creating the process: Charles Bruning Co.
and Frederick Post Co., both of Chicago. It was advertized as an
innovative process capable of reproducing the look of hand-drawn
tracings without the time and cost. Wash-off prints were relatively
expensive to produce compared to other architectural print processes.
They were used to create duplicate copies of original tracings. Since
the prints could be altered during processing, the process was also used
either to produce clean copies of damaged, soiled, or discolored
tracings or to make revisions to an original. Prior to development of
vellum paper (plasticized cotton) and polyester film in the 1950s,
wash-off prints existed primarily on glossy drafting cloth supports.
Direct positive wash-off film had some success through the 1970s.
Referred to as "wash-off Mylar," the wash-off process is still in
limited use today. The prints are also known as "silver slicks" when
made on matte polyester supports.
- Storage Environment
-
Cool storage (below 50 degrees) is recommended. Allowable Fluctuation: ±2°F; ±3% RH
|
Ideal |
Temp. |
35–65°F (2–18°C) |
RH |
35–50% RH |
Based on NISO TR01-1995
- Storage Enclosure(s)
-
Technical prints were generally not made with long-term
stability in mind; most were created quickly and cheaply to serve an
ephemeral, utilitarian purpose. As a result, many technical prints may
retain chemical residues from processing. These residual chemicals may
off-gas or cause damage if placed in contact with other prints.
Prints are usually large, and they are best stored horizontally
in flat files, preferably those made of enameled steel, stainless
steel, or anodized aluminum. Store different types of architectural
prints separately in order to prevent contact degradation. Folders cut
to drawer size are recommended, with less than 12 prints to a folder and
with interleaving sheets placed between them (both alkaline or neutral
pH). Individual prints should be stored in polyester sleeves within
folders in order to both protect particularly fragile items and separate
formats from one another. Polyester sleeves also provide additional
support during handling.
It may be acceptable to store the prints rolled if space for
flat storage is not available, but brittle or otherwise fragile prints
should not be rolled. Prints that are strong and flexible enough to be
rolled must have an interior support: a neutral pH cardboard tube (over
3" diameter) itself wrapped in polyester or neutral paper. The rolled
print and interior support may be wrapped in the neutral paper or
polyester, and they should be stored horizontally, not upright. Prints
should not be folded, since this will create fold lines that weaken the
paper and cause it to tear. All storage materials should pass the
Photographic Activity Test (PAT) as specified in ISO Standard
18916:2007.
- Storage Orientation
- Flat (preferred) or rolled.
- 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 items in cases should
be securely framed or matted using preservation-quality materials that
have passed the Photographic Activity Test (ISO 18916:2007).
Prints in stable condition may be exhibited for brief periods.
Wash-off prints should not be exposed to more than 5,000 ft-c hours
(50,000 lux hours) per year with a 3-year rest between displays. Use of
facsimiles is recommended for display.
Diazo Print (Architecture)
- Synonyms
-
- Diazotype
- Primuline process
- Whiteprint
- Ammonia print
- Gas print
- Direct print
- Dyeline
- Blueline
- Blackline
- Ozalid
- Dates
- 1923 – present
- Prevalence
- Common
- Support
- Paper, plastic film (polyester, acetate), or drafting cloth
- Fibers (paper, cloth)
- Visible under low magnification
- Ground Color
- Varies; recto (front) often smudged, flecked, or "dirty" white.
If on paper, the verso (back) will be noticeably bright white in
contrast.
- Image/Lines
- Deep blue, purple, black, or sepia brown (other colors also possible)
- Description
- The diazo print (or diazo for short) is the result of a
duplication process yielding a direct positive image. A diazo is an azo
dye line drawing reproduction of an original line drawing (frequently
deep blue or purple, but also black or brown) on a near-white
background. Fibers will be visible under low magnification. Diazos have a
smooth, lightly calendered surface. The verso (back) is usually white,
but it may show signs of discoloration in the form of yellow stripes.
May possess an ammonia odor, which can be transmitted to other documents
stored together. Sepia diazo prints (brown lines on a flecked ground)
are often printed in reverse; and, they may have a waxy or oily coating.
"Ozalid" brand paper, a common, patented diazotype paper, will have
brown-red lines and a faint rust-colored ground; it should also show the
presence of a trade name watermark.
- Composition
-
Support |
Image/Text |
Paper, drafting cloth, or plastic film |
Azo dyes |
- Deterioration
- Paper will likely be brittle due to residual chemicals, and the
edges may also be discolored. Yellow and brown discoloration is more
likely to occur on the image-side of the print and along the edges. The
diazo dye-based image/text may be faded, particularly if housed in an
acidic enclosure or exposed to light for an extended period. Residual
chemicals and light exposure can together cause yellowish-brown
discoloration in unexposed areas. Diazos must be stored separately from
most photographic materials due to their destructive off-gassing. Sepia
diazo prints, which were frequently used as intermediate images, may be
coated with wax, paraffin, or oil to increase translucency. This coating
may transfer to other objects and result in a characteristic reddish
pink discoloration or greasy smudging.
- Risk Level
- Moderately high (older prints are at higher risk). All diazo
prints should be assumed fragile and volatile. Diazos were often poorly
processed and, as a result, will contain residual chemicals harmful to
themselves and other materials stored in proximity. They are also known
to transfer color dyes to adjacent papers. Diazos should therefore be
stored separately from other materials if possible. Original drawings
and any reformatted copies should be retained. Alkaline storage
enclosures are not advised for diazo prints.
- Process
- The diazo process is similar to blueprinting and other early
reprographic processes, with some chemical differences. The support is
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 color will vary (blue,
purple, brown, etc.). Copies were produced from a translucent master
drawing placed over the sensitized paper. They are then exposed to a
strong UV light source: the master is used like a photographic negative,
in which light is blocked in dark areas (e.g. lines, text) and allowed
to pass through light areas (i.e. background). The underlying support is
then exposed to an ammonia (alkaline) gas. This gas works to catalyze a
chemical reaction to produce a print image that fixes in the paper or
cloth.
- Background
- The diazo print was the most popular of the dry printing
processes, and it is the most common large scale reprographic format
found in late twentieth century collections. Diazo prints were made as
early as the 1880s but the process was not widely used until 1923, when
the process was commercialized and Ozalid paper was marketed by Kalle
& Co. of Germany. The diazo process was primarily used for copying
technical drawings beginning in the 1920s, but it was also used for
office copying from the 1930s to 1970s. The diazo process gained
popularity quickly due to its simple dry processing and ability to
reproduce both pencil and ink lines. Diazos replaced blueprints in most
architectural and engineering offices by the 1950s, and they continue to
be produced to the present day.
- Storage Environment
-
Cool storage (below 50 degrees) is recommended. Allowable Fluctuation: ±2°F; ±3% RH
|
Ideal |
Temp. |
35–65°F (2–18°C) |
RH |
35–50% RH |
Based on NISO TR01-1995
- Storage Enclosure(s)
-
Technical prints were generally not made with long-term
stability in mind; most were created quickly and cheaply to serve an
ephemeral, utilitarian purpose. Many of these prints will retain
chemical residues from processing. These residual chemicals may off-gas
or cause damage if placed in contact with other prints. Always segregate
diazo prints from silver-image prints (i.e. Photostats, VanDykes,
Wash-Offs), as the former contains thioura, a silver-bleaching chemical.
Prints are usually large, and they are best stored horizontally
in flat files, preferably those made of enameled steel, stainless
steel, or anodized aluminum. Store different types of technical prints
separately in order to prevent contact degradation. Alkaline storage
materials are not advised for diazos. Folders cut to drawer size are
recommended, with less than 12 prints to a folder and with interleaving
sheets placed between them (both alkaline-free). Individual prints may
be stored in polyester sleeves within folders in order to either protect
particularly fragile items or separate formats from one another.
Polyester sleeves also provide additional support during handling.
It may be acceptable to store the prints rolled if space for
flat storage is not available, but brittle or otherwise fragile prints
should not be rolled. Prints that are strong and flexible enough to be
rolled must have an interior support: a neutral pH cardboard tube (over
3" diameter) itself wrapped in polyester or neutral paper. The rolled
print and interior support may be wrapped in the neutral paper or
polyester, and they should be stored horizontally, not upright. Prints
should not be folded, since this will create fold lines that weaken the
paper and cause it to tear. All storage materials should pass the
Photographic Activity Test (PAT) as specified in ISO Standard
18916:2007.
- Storage Orientation
- Flat (preferred) or rolled.
- 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 items in cases should
be securely framed or matted using preservation-quality materials that
have passed the Photographic Activity Test (ISO 18916:2007).
Although not quite as light-sensitive as cyanotypes, diazos are
still very sensitive to light. It is advisable to consider the use of
facsimiles in place of original documents for exhibition. If original
prints are displayed, it should for no longer than 3 months at 3 ft-c
maximum with a 3-year rest period between display cycles.
Hectograph Copy (Architecture)
- Synonyms
-
- Chromograph (UK)
- Composition pad
- Copygraph
- Gelatine pad/method
- Dry copy
- Indirect method
- Hektograph
- Dates
- c. 1870 - 1920s
- Prevalence
- Fairly common
- Support
- Paper (calendered: smooth, glossy), often with gelatin or alum/rosin sizing agent
- Fibers (paper)
- Not visible (highly calendered paper)
- Ground Color
- Bright white, some yellowing common
- Image/Lines
- Monochrome (violet or blue, most common)
- Description
- Hectograph image/text is commonly purple or blue color, but it
can come in other colored aniline dyes, such as brown (c. 1900).
Initially, the paper is bright white with a heavily finished, glossy
surface to control ink use. The ground will likely have yellowed if on
an acidic paper support. Hectography was most often used for handwritten
and typewritten documents, although sometimes it was also used for
technical drawings. Hectographs are very similar in appearance to diazo
prints and spirit duplicates. Image lines will appear fuzzy, and image
details will have low definition. Aniline dyes have a tendency to fade,
particularly when exposed to UV light; the resulting image may be of low
contrast.
- Composition
-
Support |
Image/Text |
Paper with gelatin or alum/rosin sizing |
Aniline dye ink |
- Deterioration
- An image/text composed of aniline dye ink is very sensitive to
UV light and water/moisture. Image fading and resulting loss of contrast
is common. Some aniline ink migration and bleeding may result from
water exposure. Although high-quality paper will retain white ground
color (with slight discoloration), the more common wood pulp paper
supports will be brittle and noticeably yellowed.
- Risk Level
- Moderate. UV light exposure is the primary risk to hectographic
(aniline dye) prints. High temperature and high humidity will accelerate
deterioration of both image and support materials. Quality of the paper
support will weigh heavily in permanence. Residual acidic chemicals on
the paper could accelerate breakdown. Alum/rosin sizing, which is
impregnated in mechanical wood pulp papers, will lead to embrittlement
and yellowing of the paper support.
- Common Size(s)
- Varied; typically large: dimensions may be over 4 feet.
- Process
- First, a gelatin-and glycerin pad is created to serve as a
transfer plate. It is softened, dissolved, and then poured into a
tray/frame, where it sets and firms up while retaining moisture. Next, a
master document or drawing is rendered in hectographic (aniline) ink.
Once the ink dries, the master is pressed face down onto the
gelatin-and-glycerin pad surface and left to allow the water-soluble ink
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 and
thus created a final positive copy. This 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 and became common as an technical/architectural
reprographic process around 1870. From that time, hectographs rose
quickly in public favor since they were regarded as the most practical
method of large-scale drawing duplication. Along with its contemporary,
the aniline printing process, hectographs remained popular as a
technical and engineering drawing duplication technique until the end of
the nineteenth century, when blueprints became the new standard.
- Storage Environment
-
Cool storage (below 50 degrees) is recommended. Allowable Fluctuation: ±2°F; ±3% RH
|
Ideal |
Temp. |
35–65°F (2–18°C) |
RH |
35–50% RH |
Based on NISO TR01-1995
- Storage Enclosure(s)
-
Technical prints were generally not made with long-term
stability in mind; most were created quickly and cheaply to serve an
ephemeral, utilitarian purpose. As a result, many technical prints may
retain chemical residues from processing. These residual chemicals may
off-gas or cause damage if placed in contact with other prints.
Prints are usually large, and they are best stored horizontally
in flat files, preferably those made of enameled steel, stainless
steel, or anodized aluminum. Store different types of architectural
prints separately in order to prevent contact degradation. Alkaline
storage enclosures are not advised for hectographs due to the pH
sensitivity of aniline dye. Folders cut to drawer size are recommended,
with less than 12 prints to a folder and with interleaving sheets placed
between them (both neutral pH). Individual prints may be stored in
polyester sleeves within folders in order to either protect particularly
fragile items or separate formats from one another. Polyester sleeves
also provide additional support during handling.
It may be acceptable to store the prints rolled if space for
flat storage is not available, but brittle or otherwise fragile prints
should not be rolled. Prints that are strong and flexible enough to be
rolled must have an interior support: a neutral pH cardboard tube (over
3" diameter) itself wrapped in polyester or neutral paper. The rolled
print and interior support may be wrapped in the neutral paper or
polyester, and they should be stored horizontally, not upright. Prints
should not be folded, since this will create fold lines which weaken the
paper and cause it to tear. All storage materials should pass the
Photographic Activity Test (PAT) as specified in ISO Standard
18916:2007.
- Storage Orientation
- Flat (preferred) or rolled.
- 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 items in cases should
be securely framed or matted using preservation-quality materials that
have passed the Photographic Activity Test (ISO 18916:2007).
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 with a 3-year rest between displays.
Gel-Lithograph
- Synonyms
-
- Ferro-gelatin
- Lithoprint
- Gel-litho
- Jelly print
- Cyanotype gelatin
- Graph process
- Fotol printing
- Dates
- c. 1910 – 1950s
- Prevalence
- Rare
- Support
- Drafting cloth or paper
- Fibers (paper, cloth)
- Partially visible
- Ground Color
- Light, usually off-white (may be slightly discolored)
- Image/Lines
- Monochrome (black but other colors possible)
- Description
- Gel-lithographs are often identified by their dense black image
lines, although nearly any color is possible. Gel-lithos are often
mistaken for original ink drawings due to the intensity of the ink
color. If made of black carbon ink, lines will exhibit little to no
fading and will appear sharp. The ground color is light, often
off-white, but may be discolored. As this is a lithographic process, the
ink will appear to sit on top of the support (paper, drafting paper)
surface: this effect will be particularly noticeable under
magnification. Most prints on drafting cloth will lose whatever glossy
surface finish they once had on the image-side due to exposure to the
gelatin pad. Surface finish loss is not necessarily true for the edges
of the cloth, which will remain glossy after avoiding contact with the
transfer pad. Gel-lithos are occasionally printed in reverse. Any
reverse-reading text will be a clear indication. Gel litho images were
also printed on the verso (back) of a semi-translucent drafting cloth to
illustrate proposed changes.
- Composition
-
Support |
Image/Text |
Drafting cloth or paper |
Oil-based carbon black ink |
- Deterioration
- Gel-lithograph images rendered in black ink are very stable.
Under reasonable conditions, pigment-based black images will remain very
stable. Color inks will be more vulnerable to light fading. The
integrity of the paper or cloth support material is the decisive factor
for gel-lithographs. For instance, the support will be yellowed,
brittle, and acidic if printed on a wood pulp paper with alum-rosin
sizing.
- Risk Level
- Low risk, especially if printed in carbon black ink. Colored
inks will be more vulnerable to light exposure. The quality of the
support will be a decisive factor in the preservation of a
gel-lithograph; avoid high temperatures and extremes of humidity.
- Common Size(s)
- Varied; often over 40" × 60"
- Process
- First, a gelatin pad is created to serve as a transfer plate. It
is softened and dissolved, poured into a tray (sometimes quite large),
where it sets and firms up but retains moisture. After this, the process
diverges into two possible methods. The first is photo-reproductive
process: a sensitized (but undeveloped) blueprint is placed under a
master document or drawing on a translucent support and exposed to a UV
light source: the master is used like a photographic negative, in which
light is blocked in dark areas (e.g. lines/text) areas and allowed to
pass through translucent spaces. The blueprint now shows a faint latent
image that can be edited with special solvents. The second method is
more akin to hectography: a document or drawing is rendered in an
"actinic" ink that dissolves when in contact with gelatin. The two
methods reconverge when the blueprint or actinic ink drawing is pressed
face-down onto the gelatin pad and then left to allow the intermediate
blueprint or actinic ink to be absorbed. When pulled away, a final
positive copy remains to be inked for image transfer. This process could
produce as many as 100 copies, each of successively lower contrast than
the preceding copy.
- Background
- Pioneered in 1900, it was not until around 1910 that
gel-lithographs gained popularity and widespread use, which it
maintained more or less until the 1950s when diazotypes rose in favor.
Although it was time-consuming, expensive, and required some skill,
gel-litho printing could produce stable, precise, and true-to-scale
images in colored ink on nearly any support--without the use of aqueous
treatments. Professionals benefitted from the ability to both print onto
a drawing paper and continue working with additional media with no risk
posed to the original drawing. Patent offices often required inked
originals, and these prints would easily pass as such. When printed onto
a tracing paper or cloth, a gel-litho could function as a reproduction
template to be utilized through other contact-printed reprographic
processes like blueprints.
- Storage Environment
-
Cool storage (below 50 degrees) is recommended. Allowable Fluctuation: ±2°F; ±3% RH
|
Ideal |
Temp. |
35–65°F (2–18°C) |
RH |
35–50% RH |
Based on NISO TR01-1995
- Storage Enclosure(s)
-
Technical prints were generally not made with long-term
stability in mind. However because gel-lithographs are essentially
photomechanical ink-on-paper (or cloth), they are among the most stable
of technical prints and may be stored with original drawings.
Prints are usually large, and they are best stored horizontally
in flat files, preferably those made of enameled steel, stainless
steel, or anodized aluminum. Folders cut to drawer size are recommended,
with less than 12 prints to a folder and with interleaving sheets
placed between them. Folders and interleaves should be pH neutral or
alkaline buffered. Individual prints should be stored in polyester
sleeves within folders in order to both protect particularly fragile
items and separate formats from one another. Polyester sleeves also
provide additional support during handling.
It may be acceptable to store the prints rolled if space for
flat storage is not available, but brittle or otherwise fragile prints
should not be rolled. Prints that are strong and flexible enough to be
rolled must have an interior support: a neutral pH cardboard tube (over
3" diameter) itself wrapped in polyester or neutral paper. The rolled
print (and interior support) may be wrapped in the neutral paper or
polyester, and they should be stored horizontally, not upright. Prints
should not be folded, since this will create fold lines which weaken the
paper and cause it to tear. All storage materials should pass the
Photographic Activity Test (PAT) as specified in ISO Standard
18916:2007.
- Storage Orientation
- Flat (preferred) or rolled.
- 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 items in cases should
be securely framed or matted using preservation-quality materials that
have passed the Photographic Activity Test (ISO 18916:2007).
Gel lithographs printed with black ink are quite stable and may
be exposed to no more than 30,000+ ft-c hours (300,000 lux hours) per
year with a 1-year rest between displays. Color images are sensitive to
light and should not be exposed to more than 5,000 ft-c hours (50,000
lux hours) per year with 3-year rest between displays.
Electrostatic Print (Architecture)
- Synonyms
-
- Photocopy
- Xerographic copy
- Electrophotography
- Plain paper electrostatic copy
- Dates
- c. 1940 – present
- Prevalence
- Common
- Support
- Plain copy paper; polyester transparency film also possible
- Paper Fibers
- Visible
- Ground Color
- White, usually off-white (may be slightly discolored)
- Image/Text Tone
- Monochrome (carbon black)
- Description
- Electrostatic copies are nearly indistinguishable from other
plain paper reprographic processes. The edges of the original scanned
document can sometimes be seen in the electrostatic copy if they were
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 continues to be one of the
most prevalent copy formats in the world. Photocopying is also a
commonly recommended, low-cost reformatting method for other at-risk
documents in archival collections.
- Composition
-
Support |
Image/Text |
Paper (uncoated) or polyester transparency |
Black toner (carbon black pigment in resin) |
- Deterioration
-
Electrostatic copies tend to be very stable and image permanent
as the toner is black carbon pigment in a resin carrier, both of which
are inert materials. While proper processing will ensure permanence, it
is also dependent upon the quality of the paper.
Electrostatic copies should be stored at moderate temperature
and relative humidity. Since the resin binders are thermoplastic
polymers with low softening temperatures, avoid storage under conditions
of heat and/or pressure. Copy ink can soften and transfer to adjacent
surfaces when it comes into contact with polyvinyl chloride plastic.
Depending on the quality of its paper support, a black xerox copy can be
expected to have good to excellent light stability.
- Risk Level
- Low. Store in a moderate environment. In addition to polyester
storage materials, avoid exposing copies to heat and pressure: any one
of these 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
-
Although xerography was first created in 1938, the first
commercial xerographic machines, which were manual, were produced by the
Haloid Company (now Xerox Corporation) in 1949. The first
semi-automatic machine, the Copyflo, was released in 1955; and a few
years later in 1959, Xerox released the first all-in-one copier, the
Xerox 914. It was at that point that electrostatic copying began to
dominate the office copying market. Single color toners were produced in
the late 1950s, but 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.
- Common Size(s)
- Varied
- Storage Environment
-
Cool storage (below 50 degrees) is recommended. Allowable Fluctuation: ±2°F; ±3% RH
|
Ideal |
Temp. |
35–65°F (2–18°C) |
RH |
35–50% RH |
Based on NISO TR01-1995
- Storage Enclosure(s)
-
Electrostatic prints should not be encapsulated or placed in
polyester enclosures. Loose, unbound records should be stored in
acid-free file folders.
Prints are usually large, and they are best stored horizontally
in flat files, preferably those made of enameled steel, stainless
steel, or anodized aluminum. Folders cut to drawer size are recommended,
with less than 12 prints to a folder and with interleaving sheets
placed between them. Folders and interleaves should be pH neutral or
alkaline buffered. Individual prints should be stored in polyester
sleeves within folders in order to both protect particularly fragile
items and separate formats from one another. Polyester sleeves also
provide additional support during handling.
It may be acceptable to store the prints rolled if space for
flat storage is not available, but brittle or otherwise fragile prints
should not be rolled. Prints that are strong and flexible enough to be
rolled must have an interior support: a neutral pH cardboard tube (over
3" diameter) itself wrapped in polyester or neutral paper. The rolled
print and interior support may be wrapped in the neutral paper or
polyester, and they should be stored horizontally, not upright. Prints
should not be folded, since this will create fold lines that weaken the
paper and cause it to tear. All storage materials should pass the
Photographic Activity Test (PAT) as specified in ISO Standard
18916:2007.
- Storage Orientation
- Flat (preferred) or rolled.
- 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 items in cases should
be securely framed or matted using preservation-quality materials that
have passed the Photographic Activity Test (ISO 18916:2007).
Light exposure during exhibition should be restricted,
especially for dye-based copies and for copies on zinc oxide coated
paper. Electrostatic copies may be displayed up to 30,000+ ft-c hours
(300,000 lux hours) per year with a 1-year rest between displays.
Related Notes
Oversize Materials
"Oversize"
is a designation for items that do not easily fit into the common
folder, archival box, or container without being rolled, folded, or
placed flat in a file cabinet. For more on the storage of oversized
formats, see the NEDCC’s leaflet Storage Solutions For Oversized Paper Artifacts.
Handling oversize materials is inherently tricky, especially for one
person. To minimize risk, place a thick support (e.g. heavyweight folder
or corrugated paper board) under the item as a rigid support when it is
being moved about. You can also minimize risk by having someone assist
you when transporting or handling oversize materials.
Resources
- American National Standards Institute (ANSI). (1988). American
National Standard for Imaging Media-Photographic Processed Films,
Plates, and Papers-Filing Enclosures and Storage Containers. No. ANSI IT9.2-1988. Retrieved from: https://law.resource.org/pub/us/cfr/ibr/001/aimm.it9.2.1998.pdf
- ISO. (2007). 18916 Imaging Materials: Processed imaging
materials–Photographic activity test for enclosure materials. Geneva,
Switzerland: International Organization for Standardization.
- Kissel, E. & Vigneau, E. (1999). Architectural
photoreproductions: A manual for identification and care. New Castle,
DE: Oak Knoll Press.
- National Information Standards Organization. (1995).
NISO-TR01-1995: Environmental guidelines for the storage of paper
records. Bethesda, MD: NISO Press.
- Northeast Document Conservation Center. (n.d.). Storage
solutions for oversized paper artifacts. Andover, MA: Northeast Document
Conservation Center. Retrieved from: http://www.nedcc.org/free-resources/preservation-leaflets/4.-storage-and-handling/4.9-storage-solutions-for-oversized-paper-artifacts
- Nicholson, K. (1989). Photocopier hazards and a conservation case study. The Book and Paper Group Annual, 8. Retrieved from http://cool.conservation-us.org/coolaic/sg/bpg/annual/v08/bp08-05.html
- Price, L.O. (2010). Line, shade and shadow: The fabrication and
preservation of architectural drawings. New Castle, DE: Oak Knoll Press.
- For additional resources, see Architectural Drawing Reproduction.