Chapter 3
Flexible Negatives
This chapter discusses paper-based stripping films, and self-supported films of gelatin, nitrate, acetate, and celluloid.
There have been many inventions that were conceptually
correct but that suffered from early commercial problems caused
by materials limitations. Some prominent examples were the
pneumatic automobile tire, cylindrical phonograph records, and
flexible photographic negatives.
The first negative of any kind was Talbot's paper calotype.
Glass plates coated with sensitized collodion soon superseded
calotype negatives and dominated photography for three decades.
But glass plates were heavy, breakable, expensive, and had to
be loaded in the camera one at a time. The fledgling plastics
industry was able to mold Daguerreotype cases but not thin
transparent flexible films of optical quality capable of
resisting photographic chemicals.
Stripping films:
Attempts were made to coat glass plates with collodion or
gelatin, then to strip off the coatings and expose them in
cameras without the glass. But the films were flimsy to handle,
they swelled erratically in solutions, and their light
sensitivity was much too low.
The first Kodak camera, No. 1, used stripping film in a round
format 2 1/2 inches in diameter. The silver gelatin emulsion
was coated on a sub layer of soluble gelatin on a strip of
paper base holding 100 frames. After exposure by the customer
the camera was returned to Eastman Kodak for processing. The
paper was steamed to dissolve the soluble layer, and the
emulsion was transferred to clear gelatin for development and
printing.
This process was first introduced in 1886 and used in Kodak
No. 1 in 1888; it was available until 1891, although Kodak No.2
with a 3 1/2 inch format was introduced in 1889. It was
gradually supplanted by the nitrate base; these processes
overlapped chronologically.
In order to make the most of the compactness and light weight
of stripping films, one more invention was needed, and it
appeared right on cue - the spool. Actually it was a complete
mechanism with supply and take-up spools and rollers for
holding the film flat. Eastman and Walker patented their roll
film holder in 1884. Leon Warnerke had patented a roll-film
holder in 1875 for gelatin silver bromide emulsions on paper,
and Melhuish and Spencer also patented a roll holder for
calotypes in 1854, but neither came into general use.
Litigation ensued as it did so often in the evolution of
photography, but the Eastman-Spencer holder was the right
product at the right time. The first Kodaks used rolls of paper
negatives, but the paper grain was objectionable just as it had
been in calotypes, and Eastman paper negatives were supplanted
by stripping films within a year. Stripping films, in turn,
lasted about six years until good quality nitrate film
appeared.
Surviving specimens of stripping films are relatively fragile
and rare; informed recognition and careful handling are
necessary if remaining examples are to be saved.
Cellulose Nitrate:
Collodion film base was patented in 1856 but the fabricated
product remained poor in quality for the next thirty years.
Celluloid, invented in 1869, is a thermoplastic cellulose
nitrate, often called guncotton, plasticized with camphor. This
formulation, while adequate for billiard balls and shirt
collars, was unsuited for optically clear sheets. For a time
John Carbutt in Philadelphia made and sold photographic plates
cut from solid blocks of celluloid; this heroic process
produced unbreakable plates lighter than glass, but still not a
roll film.
Manufacturing technology finally caught up with need in 1889
when Eastman chemists patented the first nitrate film. Like
celluloid it was basically cellulose nitrate, but with
different plasticizers and solvents. In 1892 Samuel Turner
invented the familiar black paper backing with numbers visible
in a red window. It was marketed by the Boston Camera Company,
which George Eastman soon bought and merged. Photography had
come a long way in six decades.
The Need for Safety Films:
Collodion, celluloid, and nitrate films are all extremely
flammable. Fires from nitrate film in movie projection booths
were not uncommon as the movie industry grew. The displaced
vaudeville industry had adopted asbestos stage curtains; movies
put the hazard at the other end of the theater. Film was
obviously flammable, but safety film had not yet been invented,
so fires had to be accepted as an unavoidable risk in a new and
exciting entertainment medium.
The long-term problem of inevitable spontaneous decomposition
of nitrate film in all storage conditions was slower to be
recognized. Nitrate film evolves fumes containing nitric acid
and various organic decomposition products, ending in total
disintegration or fire. The flash point may go as low as 120
degrees Fahrenheit. The rate of decomposition depends on the
original formulation, film thickness, and type of roll. Cine
film is more hazardous than flat sheets because it is tightly
rolled, and the decomposition products cannot escape as rapidly
as they form, thus accelerating decomposition.
Students of chemistry may see an apparent contradiction with
the usual rule that reaction products on the right side of a
chemical equation must be removed for the reaction to proceed.
This is true of simple reactions, but nitrate film is
inherently unstable (does not reach equilibrium), and
deterioration is caused by complex reactions whose products are
progressively corrosive. The most comprehensive and up-to-date
discussion of the problem is in the 1985 book by Eastman Kodak
[47, 89-93]. A vividly illustrated article by Michael Hager
appears in Image [69]. Young [159] also provides a good
reference.
Safety film in the form of cellulose acetate first appeared in
1933 in X-ray film, but professional 35mm nitrate film was made
as recently as 1951. Dates of consumption of unused stock
cannot be ascertained; Eastman Kodak states [47] "any negatives
made before 1950 are suspect". The best course of action is to
test any negative that does not show the legend "safety film"
along the margin.
Several tests are described in reference 47. Safety film will
burn, though not as rapidly as the almost explosive combustion
of nitrate film. A small clipping of nitrate film sinks in the
solvent 1,1,1 trichloroethane (trichloroethylene), while safety
film floats. This solvent is obtainable from laboratory
suppliers; it is hazardous to breathe. Details of this and
other tests can be found in reference 47, and in Rempel
[124].
The storage of nitrate negatives is the most serious single
hazard in archival management. One long-term solution is to
copy the images on modern film and then destroy the nitrate in
an approved manner. Freezing is often used as a temporary
expedient; its long-term efficacy is debated.
Chronology of Flexible
Negatives
The major steps in the evolution of flexible negatives are
summarized below. Other individuals published suggestions or
otherwise made contributions, and the literature should be
consulted for additional details, particularly Gernsheim [61,
405-409] and Eder [48, 485-490].
1855: Frederick Scott Archer patented a collodion stripping
film on paper, reinforced with a gutta-percha coating. This
appears to be the first flexible transparent negative.
1856-7: variations by Reade, Parkes, and Ferrier, not
commercial.
1875: Leon Warnerke produced rolls of chalk-coated stripping
paper with collodion or gelatin sensitive layers on a collodion
and india rubber substrate. It was made and sold in London for
use with his patented roll-film holder.
1882: Alfred Pumphrey manufactured collodion-on-gelatin cut
film for plate cameras and the Pumphrey magazine camera.
1883: a commercial stripping film introduced by Georges
Balagny in France: sensitive gelatin emulsion on collodion on
talc-coated paper for ease of stripping. It was manufactured by
the Lumiere brothers who later made the successful Autochrome
color film. In 1886 Balagny introduced a sheet film version,
comprised of alternate layers of collodion, varnish, and
gelatin.
1884: George Eastman patented gelatin silver bromide stripping
film on paper; this was manufactured from 1885 to 1889, using
the Walker film holder.
1888: John Carbutt of Philadelphia manufactured gelatin dry
plates coated on celluloid 0.25 mm thick. They were light and
unbreakable, and were made in quantity.
1889: Eastman nitrate film began to supplant stripping film
for rolls. Until the early 1900's the film was thin and easily
curled.
1892: black paper backing with negative numbers visible
through a red window in the camera back, introduced by Samuel
Turner of the Boston Camera Co.
Recognition:
Most of the surviving specimens of these types are fragile and
yellowed. Their composition can be determined by analytical
methods, and possibly by the tests in Rempel [115], but many of
the types are sandwiches of different materials such as
collodion, gelatin, or rubber. All paper-based negatives and
stripping films are of historical interest and can usually be
identified by inspection.
Sometimes the image size can be a clue in dating. Following is
a list of the standard film sizes, from several sources:
TABLE 1
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Film Number | Date Introduced | Date Discontinued | Image Size |
101 | 1895 | 7/1956 | 3-1/2 x 3-1/2 inches |
102 | 1895 | 9/1933 | 1-1/2 x 2 |
103 | 1896 | 3/1949 | 3-3/4 x 4-3/4 |
104 | 1897 | 3/1949 | 4-3/4 x 3-3/4 |
105 | 1897 | 3/1949 | 2-1/4 x 3-1/4 |
106 | 1898 | 1924 | 3-1/2 x 3-1/2 |
107 | 1898 | 1924 | 3-1/4 x 4-1/4 |
108 | 1898 | 10/1929 | 4-1/4 x 3-1/4 |
109 | 1898 | 1924 | 4 x 5 |
110 | 1898 | 10/1929 | 5 x 4 |
111 | 1898 | N.D.L. | 6-1/2 x 4-3/4 |
112 | 1898 | 1924 | 7 x 5 |
113 | 1898 | N.D.L. | 9 x 12 cm. |
114 | 1898 | N.D.L. | 12 x 9 cm. |
115 | 1898 | 3/1949 | 6-3/4 x 4-3/4 |
116 | 1899 | 4/1984 | 2-1/2 x 4-1/4 |
117 | 1900 | 3/1949 | 2-1/4 x 2-1/4 |
118 | 1900 | 8/1961 | 3-1/4 x 4-1/4 |
119 | 1900 | 7/1940 | 4-1/4 x 3-1/4 |
120 | 1901 | 2-1/4 x 3-1/4 | |
121 | 1902 | 11/1941 | 1-5/8 x 2-1/2 |
122 | 1903 | 4/1971 | 3-1/4 x 5-1/2 |
123 | 1904 | 3/1949 | 4 x 5 |
124 | 1905 | 8/1961 | 3-1/4 x 4-1/4 |
125 | 1905 | 3/1949 | 3-1/4 x 5-1/2 |
126 | 1906 | 3/1949 | 4-1/4 x 6-1/2 |
127 | 1912 | 1-5/8 x 2-1/2 | |
128 | 1912 | 11/1941 | 1-1/2 x 2-1/4 |
129 | 1912 | 1/1951 | 1-7/8 x 3 |
130 | 1916 | 8/1961 | 2-7/8 x 4-7/8 |
35 | 1916 | 1/1933 | 1-1/4 x 1-3/4 |
616 | 1932 | 5/1984 | 2-1/2 x 4-1/4 |
620 | 1932 | 2-1/4 x 3-1/4 | |
828 | 1935 | 2/1985 | 28 x 40 mm. |
N.D.L. = No Domestic Listing, usually for sale outside the U.S. |
Some image sizes were duplicated on different spool widths: the first number in the listed dimensions corresponds to the roll width. Examples are numbers 103 and 104. Number 103 had the long dimension of the image in the direction of the roll length, while 104 was on a wider spool with the short side of the image in the direction of the roll. When separated negatives are examined, the separation cuts are usually not as straight as the original roll edges, so the image orientation can often be deduced.