An Improvement in the Manufacture of Photographic Plates.
Year: 1893

page_text: Date of Application, 20th Mar., 1893
Complete Specification Left, 20th Dec., 1893-Accepted, 20th Jan., 1894
PROVISIONAL SPECIFICATION.
An Improvement in the Manufacture of Photographic Plates.
I, OTTO MAGERSTEDT of No. 183 Reichenbergerstrasse Berlin, in the German
Empire. Merchant do hereby declare the nature of this invention to he no
follows:
This invention relates to an improvement in the preparation of photographic
plates, and its purpose is to avoid the defects of halation and solarization.
It is well known that photographic images of subjects presenting strong contrasts
of light and shade, prepared with the plates hitherto generally in use, are liable to
halation and solarization. Many attempts have been made to avoid this defect;
but none of them have entirely removed it. These attempts, moreover, were
mostly attended with inconvenience in the preparation or the mode of employing
those plates, and the preparation of such plates, as for instance the so-called
Sandell-plates was complex and very expensive.
I have discovered that, in a very simple way, which is capable of generat
application, photographic plates can be prepared, by the use of which the defects
above mentioned can be entirely avoided.
For this purpose, between a layer of haloid silver emulsion and the material
carrying it (glass, film or the like) I place a coloured layer prepared from
colouring matters, which before, during, by or after developing or fixing, can be
removed or rendered colourless.
I thoroughly clean the plate and coat it with this layer, which consists of a
solution of the colouring matter in gelatine, I dry the coating, and over it I put
the sensitive layer.
As colouring matters, preferably employed for this preparation of plates, the red
colours of the rosaniline series and their sulphoacids are used, also those of the
rosolic-acid series, and the products ranging in constitution between the two series
mentioned above, the red and yellow dyes obtained by the so-called Aurine-process,
also the safranines, phosphines, uranines and the like.
Dated this 20th day of March 1893.
ABEL & IMRAY,
Agents for the Applicant.
COMPLETE SPECIFICATION.
An Improvement in the Manufacture of Photographic Plates.
I, OTTO MAGERSTEDT, of No. 183 Reichenbergerstrasse, Berlin, in the German
Empire, Merchant, do hereby declare the nature of this invention and in what
manner the same is to be performed to be particularly described and ascertained in
and by the following statement :-
This invention relates to an improvement in the preparation of photographic
plates, and its purpose is to avoid the effects of halation and solarization.
It is well known that photographic images of subjects presenting strong contrasts
of light and shade, prepared with the plates hitherto generally in use, are liable to
halation and solarization. Many attempts have been made to avoid this defect;
but none of them have entirely removed it. These attempts, moreover, were
mostly attended with inconvenience in the preparation or the mode of employing
Price 8d.1

page_text: those plates, and the preparation of such plates, as for instance the so called
Sandell-plates was complex and very expensive.
I have discovered that, in a very simple way, which is capable of general
application, photographic plates can be prepared, by the use of which the defects
above mentioned can be entirely avoided.
For this purpose, between a layer of haloid silver emulsion and the material
carrying it (glass, film or the like). I place a coloured layer prepared from
colouring matters, which before, during, by or after developing or fixing, can be
removed or rendered colourless.
I thoroughly clean the plate and coat it with this layer, which consists of a
solution of the colouring matter, such, for example, as magenta, in gelatine. I
dry the coating, and over it I put the sensitive layer of haloid silver emulsion in a
weak red light, then dry the plate in a dark room. The plate thus prepared is
ready for use.
As colouring matters preferably employed for this preparation of plates, the red
colours of the rosaniline series and their sulpho acids are used, also those of the
rosolic acid series, and the products ranging in constitution between the two series
mentioned above, the red and yellow dyes obtained by the so called Aurine process,
also the safranines, phosphines, uranines, and the like.
By treating a plate prepared as above described with an acid fixing bath and
afterwards well washing, it is rendered colourless.
When certain developers are employed, as for instance, "Rodinal" (aqueous
solution of para-amide-phenol-sodium) the discoloration takes place in the developing
bath.
Having now particularly described and ascertained the nature of this inven-
tion and in what manner the same is to be performed, I declare that what I
claim is:-
:-
1. The manufacture of photographic plates by placing between the sensitising
haloid silver emulsion and the plate itself a layer coloured with dyes of the kind
specified, substantially as and for the purpose set forth.
2. Photographic plates prepared substantially as herein described.
Dated this 11th day of Decombor 1803
ABEL & IMRAY,
Agents for the Applicant.