Camera Work: A Photographic Quarterly (1905 (Heft 11))

PERFECTED GELATINE OZOTYPE.

THE ADVANTAGES which ozotype possesses over all other
photographic pigment processes should entitle it to a place in the
front rank of popular appreciation. There is a distinctly visible image
during exposure which no other pigment process presents. It can be
worked in either a gelatine or a gum medium. In gelatine ozotype no
transfer is required as in carbon-printing, and in working with gum the
insolubilizing action commences from the surface of the paper and
penetrates through the pigmented gum, making it a theoretically perfect
process. In ordinary gum bichromate the more insoluble portion of the
gum film is on the top, away from the paper, and it requires a perfectly
homogeneous and exceedingly thin film of the medium to produce the
requisite half-tone.
It is remarkable that all the photographic processes which were destined
to become popular suffered from imperfections when first placed upon the
market, but a long course of experience and observation on the part of the
inventors surmounted the initial defects and the processes leaped into
popularity. Eight years elapsed between the discovery of the gelatine dry
plate and the commencement of its commercial prosperity. The carbon
process took a much longer time to become popular. Ozotype has been no
exception to the rule; but during a period of four years before the public
so much experience has been gained by a close study of the quality of the
materials and the delicate chemical actions involved that it may now be
regarded as the easiest and most reliable pigment process. It is unique
among pigment printing methods, inasmuch as it gives a distinctiy visible
image during exposure, and the direction of the insolubilizing action from the
paper through the film is scientifically correct. When once the scientific
principle of a process is firmly established it is through improvements in
materials that perfection is arrived at.
A brief description of the process is as follows:
1. Any good paper is sized with gelatine or starch.
2. The sized paper is coated with the ozotype patent sensitizing
solution and dried in the dark.
3. The exposure is made in daylight, producing a distinctly visible
image.
4. The print is washed in cold water.
5. A piece of pigment plaster (which is carbon tissue specially modified
for this process) is placed in a very dilute solution of acidulated sulphate of
copper and hydroquinone for about half a minute; the print is then
immersed in the bath and both the print and plaster, clinging together, are
brought out and laid upon some smooth hard surface and pressed into contact
with a flat squeegee. The combined papers are then hung up until ready for
development.
6. At the expiration of thirty to forty-five minutes the combined
papers are immersed in a bath of water at 115° F.; the plaster backing is

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