Computer Program for Identification of Photographs
The FOTOFIND program on the disk accompanying this book starts
with three questions to establish whether the unknown picture
is on paper, glass, or in a group of miscellaneous bases
including metals. The answer to these screening questions
determines which of three groups of questions are presented to
the user. The three groups contain respectively ten, eight, and
nine questions, thus limiting the questions to the ones most
relevant to the base material. Some questions are yes/no, while
others are multiple choice; all are prompted on the screen. The
operator is instructed to type "u" for "uncertain" wherever
there is doubt. Details of the program are given in Appendix
III; instructions on answering the questions are listed below.
Many history books choose to group photographic processes in
such categories as silver and non-silver. However logical these
categories may be for teachers or historians, they are not
useful for an identification search. Archivists who are
confronted with boxes of old photographs do not usually sort
them into two piles of silver and non-silver, because there is
no simple observational way to do it. This is the reason base
materials were chosen as a first screen.
The program loses its ability to distinguish between types of
photographs made after approximately 1900, based on simple
visual observations; other types of analysis are then needed.
How to run FOTOFIND
(NOTE: SINCE THE WRITING OF THIS MANUSCRIPT FOTOFIND IS NOW AVAILABLE AT
THE SHARLOT HALL MUSEUM'S WEB SITE)
This version of FOTOFIND runs in Microsoft DOS or Microsoft
Windows 98; it will not run under MicroSoft Windows 3.x or 95.
Windows 98 users can run it by several methods (UPPER or lower
case may be used in the following procedures):
1) Go to the DOS command in the Programs menu, then enter the
drive containing the FOTOFIND disk. The starting command is
2) Reboot the system from a floppy disk containing the DOS
command files, or restart the computer in the MS-DOS mode from
the SHUTDOWN command in the START menu.
3) In Windows 98 desktop, enter the opening menu with the START
key. Go to RUN, enter the drive followed by the file name, eg -
4) Find the program in "My Computer" on whatever drive you have
installed foto27.exe, and double click on it.
In modes 3 and 4, the display should be expanded for best
foto27.exe may be installed on a hard drive in a directory such
as c:\FOTOFIND\ which allows easy and quick access. It only
requires about 180 kb disk space. FOTOFIND creates temporary
*.dat files on its drive when it is run, for each of the base
materials entered. These files are small, and can be deleted at
any time to save space, without interfering with subsequent
Reports can be printed either from DOS or Windows 98. The
printer response time is faster under DOS than under Windows
98, and the DOS screen looks better. If printing problems are
encountered on a particular machine in Windows operation, DOS
operation should be satisfactory. In either case, screen
displays and search times will be nearly instantaneous on most
Apple machines should be able to run FOTOFIND with a suitable
conversion program. At this writing we have no specific
instructions on running FOTOFIND on Apple machines, nor on
Windows NT or ME. Future upward compatibility, of course,
cannot be predicted, which is a well known problem with
archival data storage and retrieval.
Notes on answering the questions
Is the picture on paper?
Usually this is self-evident, even if the picture is framed
Is the image on glass?
One possible ambiguity is the crystoleum or Crystal photograph,
which was an albumen print sealed to the underside of a convex
cover glass, which is included in the listing of glass bases.
Pictures framed under glass should not be confused with images
printed on glass.
If both the above answers concerning bases are 'no', the
program brings up the questions pertaining to miscellaneous
Questions on Paper Photographs
1. Is the image a positive or negative?
Generally a self-evident question except perhaps for
ambrotypes, which were made as negatives but viewed as
positives. Ambrotypes were coded as positives based on their
2. Is there a baryta subcoat?
A baryta coating was used under the photosensitive layers of
all commercial papers starting in the 1880's (see chapter 3).
This included bromide, chloride, and chlorobromide papers such
as Aristo and gaslight varieties with both gelatin and
collodion emulsions. It is usually markedly whiter compared to
albumen and earlier papers; also the baryta completely covers
the paper fibers in highlights and shadows.
It is impractical to identify separately all of these types by
the questions in FOTOFIND. Close examination is necessary,
possibly augmented by chemical or physical analysis. Answering
"yes" to the baryta question serves to catagorize a print to a
group of commercial papers fron the 1880's on.
3. Is the image faded?
Fading is a lightening effect, not to be confused with staining
or spotting. It is difficult to evaluate without a comparison
with the original appearance, yet it can be an important
descriptor. Here are some clues:
Platinotypes have a long tonal range and soft shadows, but are
not faded because of their stable chemistry. On the other hand,
calotypes usually have low contrast because they are faded.
Albumen prints are nearly always faded; their color has been
variously described as brownish, rose, sepia, and yellow. Their
faded yellow color is almost unique: a yellow print is likely
to be an albumen, but not all albumens are yellow. Among the
types that are never faded are carbon, carbro, gum, and all
inked prints such as collotypes. Note that these images do not
fade, although the paper base may have become brown or
yellowed. Cyanotype images are stable and they were coded as
not faded, but they have a short tonal range and both
highlights and shadows may be distinctly blue. It may be due to
original overexposure or contaminated chemicals in the
processing, which causes a gradual increase in blue density
over the years. However, cyanotypes will fade if they are
stored in contact with buffered archival paper.
In general, prints made late in the 19th century are less
likely to be faded than earlier ones, and their highlights will
be whiter because of baryta undercoating. Silver bromide and
chloride prints, except certain POP papers such as Aristo, did
not contain excess silver nitrate as early salt prints did. If
bromide prints faded, the cause was usually insufficient fixing
or washing, which showed up as uneven spotting and fading. Many
prints were toned gold or sepia to improve stability, producing
a brownish color.
4. Is the image color black, brown, blue, gray, yellow,
purple, or "u"?
The above remarks on fading should first be reviewed, along
with Chapter 10. Color can be an important clue, but it is
difficult to describe colors verbally. Some of the carbon
processes included pigments or dyes: the Autotype Company
advertised more than fifty colors. Most dyes were unsaturated,
or pastel. Sepia and brown are similar, and brown was coded as
the descriptor. The ink used in collotypes was generally black,
but colors were used in intaglio printing. Cyanotypes are
uniquely blue or blue-black, and most platinotypes are a
distinctive silver gray or neutral black that was called gray
rather than silver to avoid confusion with Daguerreotypes and
brown platinotypes. In case of doubt about the color of any
print, type "u" for the first run, then try running with other
5. Is the surface glossy, matte, matte fibers, or glossy
"Glossy" includes smooth, which is a minor variation. Matte
surfaces were made by adding cornstarch to the emulsion, or by
mechanical stippling, which can be observed microscopically.
Both glossy and matte are emulsion-coated overall, usually with
a baryta undercoat that hides the fibers. "Matte fibers" means
that the paper fibers are exposed over the entire surface.
"Glossy shadows only" refers primarily to gum and carbon
processes; the shadows are coated with gelatin but the
highlights show exposed paper fibers where the gelatin was
washed away during development. These surface types can usually
be identified with a hand magnifier or with a microscope and
illumination at grazing angle, concentrating on differences
between shadows and highlights. Some emulsion reticulation
patterns look almost like fibers: a microscope is needed.
Gelatin emulsions coated by photographers were sometimes so
thin that fibers are visible; adjustment of the microscope
light will show small areas of sheen between the fibers. This
is also true of albumen paper, which had no baryta undercoat:
the fibers are visible but not exposed, so the descriptor is
6. Are the shadows heavily tarnished?
Many silver processes show this effect to some degree, but it
is so pronounced with gaslight papers and nitrate negatives
that it is a fairly reliable identifier. It is also known as
bronzing, silvering, or mirroring, and is caused by deposition
of metallic silver on the surface by processing residues or
7. Is the picture glued to an embossed card mount?
Although many paper photographs were mounted on cardboard, this
question refers to cartes-de-visite, cabinet cards, and others
with specific dimensions listed in Chapter 9. These mounts were
usually printed with the photographer's name or studio on front
or back, sometimes with advertising messages, and with
decorative borders; they have a manufactured look. Processes
include albumen, aristo, and chlorobromide papers, and some
carbon and Woodburytypes. Tintypes were often mounted on small
cards behind a thin paper cutout, and this is included as a
tintype descriptor; it is easily distinguished from other card
8. Is there a screen pattern?
The commonest example is the geometrical dot pattern in
screened newspaper halftones, a positive indication of an inked
print. Other screen patterns are random dots and reticulated
line patterns, all examples of ink prints: see Chapter 5. These
patterns are coarser than photographic grain and can be seen
under low magnification.
9. Are paper fibers visible in highlights only?
Emulsion-coated papers that did not have a baryta undercoat
reveal paper fibers through the translucent coating. It is
visible only in highlights because shadows are opaque. Careful
lighting and magnification may be necessary. A clue is the
color of highlights: baryta retained its whiteness better than
most uncoated papers, which have usually yellowed in a century.
10. Is the picture retouched to look like a
Many early portraits were tinted to some degree, but in some
"crayon" prints the retouching essentially obscured the
underlying image. Both colored tints and charcoal were used.
Sometimes the silver image was chemically weakened or removed
to foster the impression of a free-hand drawing or painting.
See Appendix II.
Questions on Glass Photographs
1. Is the image a positive or negative?
It is often necessary to use lighting at various angles to
2. Is the picture in a hinged case?
This question refers to the distinctive cases of ambrotypes,
Daguerreotypes, and tintypes. These cases originally had hinged
covers and glass over the picture; the covers are sometimes
missing today. Metal lockets on chains are not identifiers of
any particular photographic process.
3. Is the picture magnetic?
All tintypes are magnetic, and some transferotypes may also be:
see Chapter 9. A weak magnet is adequate for testing; a
magnetic compass can sometimes be used.
4. Do the highlights show silver reflections?
This is a property unique to Daguerreotypes; it is a specular
or mirror reflection. Tarnish and reflections from the cover
glass can hinder the observation, but the tarnish (usually
occurring in a diffuse zone around the edge) helps distinguish
Daguerreotypes from ambrotypes and tintypes.
5. Is the image reflection tinted, milky, or dark?
The difference in reflection color is most visible in the image
shadows; see Chapter 6.
6. Is the transmission color brown, black, or tinted?
Daylight viewing is preferred.
7. Is the glass flat, curved, or milky?
Milky refers to opal glass, not to be confused with the
reflection in question. Curved means part of a spherical
surface, convex to the viewer.
8. Is the edge coating even or uneven?
This refers mostly to wet-plate collodion negatives: hand
coating was uneven at the edges. Ambrotypes are cased and their
edges are not visible without dismantling; the same is true of
bound lantern slides. The descriptor is based on what is
normally visible to the viewer without taking things apart.
Questions on Metal, Cased, or Other Types of Photos
1. Is the picture a positive or negative?
Rarely a problem with most subject matter in adequate light.
2. Is the picture in a hinged case?
See comments in number 2 under glass photographs.
3. Is the image on a flexible transparent base?
This question refers to what is now called "film". It does not
include translucent bases such as paper negatives (waxed,
oiled, or plain), which are coded under "paper" and "negative."
4. Is the picture fixed to a card mount?
Some Gem tintypes were mounted in tiny brass frames that were
crimped to a card mount. Other tintypes were mounted on cards
behind a thin paper cutout. Many pictures were simply glued to
cardboard, either plain or decorated. Plain cardboard is not a
helpful clue, but decorations are fairly well documented; see
5. Is the picture magnetic?
See comments in number 3 under Glass Photographs. Glass is not
magnetic, but cased tintypes sometimes resembled ambrotypes,
and the magnetic test is simple and definite.
6. Do the highlights show silver reflections?
See comments in number 4 under Glass Photographs.
7. Is the picture printed on fabric?
Several processes were printed on different kinds of fabrics.
Most are fragile and rare.
8. Is the picture printed on leather?
The leather was sometimes lacquered to resemble japanning, and
is fragile and rare.
9. Is the picture printed on metal?
The commonest example was the tintype, but transferotypes were
made on many metals. Some were non-magnetic, such as copper and