IMPROVEMENTS IN PHOTOGRAPHIC PAPER AND IN SENSITIVE EMULSIONS THEREFOR
Year: 1885

page_text: [Communicated from abroad by E. and H. T. Anthony and Company, a Corpora
tion incorporated under the Laws of the State of New York, of the City
County, and State of New York, United States of America.]
"
I, ALEXANDER MELVILLE CLARK, of the firm of A. M. and Wm. Clark, of
53, Chancery Lane, in the County of Middlesex, Fellow of the Institute of Patent
Agents, do hereby declare the nature of the said Invention for "IMPROVEMENTS
IN PHOTOGRAPHIC PAPER AND IN SENSITIVE EMULSIONS THEREFOR (a communi-
cation to me from abroad by E and H. T Anthony and Company, a corporation
incorporated under the laws of the State of New York, of the City, County, and
State of New York, United States of America) and in what, manner the same is
to be performed, to be particularly described and ascertained in and by the following
statement:-
This Invention consists in the production as a new article of manufacture, of a
photographic printing paper having a toothed facing of gelatine and bromide of
silver; and it further includes a compound, for facing photographic paper, con-
sisting of gelatine, bromide of silver, and a suitable toothing substance substantially
as hereinafter described; likewise a combination with a photographic emulsion of
gelatine and bromide of silver, of a toothing substance such as the sulphate of
baryta.
Heretofore when a sheet of paper has been coated with a gelatine emulsion
sensitized with a bromide of silver, the surface when dry, has been smooth and
incapable of having a tooth to receive and hold the mark of a crayon or pencil.
By this Invention however it is practicable to obtain in a quick and simple manner,
a mat or roughened surface on gelatine bromide paper, suitable for positive
photographic printing, which shall have tooth for touching or marking it with
crayon, lead pencil, pastels &c and this it does by directly mixing a suitable
toothing substance with the gelatine emulsion sensitized with a bromide of silver,
and then applying to the surface of the paper, in the usual or any suitable manner,
said sensitive emulsion, having the toothing substance, which is insoluble therein,
incorporated with it,

page_text: Thus there is obtained in a quick and simple manner a mat or roughened
surface on gelatine bromide paper for positive photographic printing so as to give
tooth for touching or marking it with crayon, lead pencil, pastels &c, and it is
practicable to prepare a rapid printing paper having a toothed surface for enlarging
purposes either by the solar camera or other enlarging apparatus.
In carrying out the invention, the gelatine bromide of silver compound it is
preferred to employ is a previously known and peculiarly prepared one which
consists in first softening the gelatine in water and adding bromide of ammonia or
an equivalent bromide in suitable proportions, say about one hundred and fifty
grains of good gelatine, sixty grains of bromide of ammonia and about five ounces
of water, then dissolving the gelatine by heat and adding gradually nitrate of
silver say about one hundred grains dissolved in about five ounces of water; then
subjecting the whole to a continued heat for two or three days, more or less, at
about 80° or 100° Fahrenheit, then after allowing it to cool and set, cutting it into
fragments and washing out the soluble matter, then melting it by heat and adding
about its weight of water. To this or other like emulsion is then added for each
four fluid ounces thereof, about one tea-spoonful, more or less, of the insoluble
toothing substance, and thoroughly incorporated therewith. To produce a very
coarse grained or toothed surface, double the quantity specified of the insoluble
graining or toothing substance may be incorporated with the sensitive material
or emulsion. Different toothing substances insoluble in said emulsion might be
used including the sulphate of baryta, pumice stone powder or emery powder of
different grades, and the paper to which said sensitive emulsion is applied may
either be sized or unsized and said gelatine bromide of silver emulsion, having the
insoluble toothing substance incorporated with it, may be applied to the surface of
the paper on which the positive photographic printing is to be done in any suitable
manner known to the arts for applying other or simple emulsions.
If the graining or toothing substance used be sulphate of baryta, which gives
a superior finish to the white portions of the picture, then said sulphate may be
used in a wet state, as when used in a damp state it readily assimilates with a
gelatine emulsion and is held in suspension therein.
It might however be used in a dry state, in which case, the proportion may be
about one dram of sulphate of baryta to each ounce of the sensitive emulsion, first
mixing it however in a weak solution of gelatine and water and afterwards mixing
and incorporating it, in any suitable manner with the sensitive emulsion. Said
sulphate of baryta will be held in suspension just as the bromide of silver is held
and does not affect the sensitiveness of the emulsion.
:
By incorporating an insoluble graining or toothing substance with the gelatine
and bromide of silver, all special or mechanical means for producing a grained or
toothed surface upon the paper are dispensed with and by means of a gelatine
bromide of silver emulsion having a toothing substance incorporated with it as
described, the usual method of producing a mat or roughened surface upon the
paper by rubbing down the surface of the print with cuttle-fish bone and pumice
powder is dispensed with and it is practicable to quickly prepare a surface superior
in uniformity to that heretofore produced for the purposes specified.
From the foregoing .description it will be seen that by this Invention is
produced a sensitive photographic printing paper having all the rapid printing
and developing qualities of bromide of silver paper, with the added quality, that
the print when toned and finished in the ordinary manner has a roughened or
toothed surface and may be then touched and worked up by pencil or crayon.
Having now particularly described and ascertained the nature of the said
Invention and in what manner the same is to be performed I declare that what
I claim is
1st As a new and useful or improved article of manufacture, a photographic
printing paper made with a toothed facing of gelatine and bromide of silver as.

page_text: 2nd The within described compound for facing photographic paper, consisting of
gelatine, bromide of silver, and a suitable toothing substance, such as the sulphate
of baryta, prepared in the manner and proportions substantially as described.
3rd The combination with a photographic emulsion of gelatine and bromide of
silver, of a toothing substance, such as the sulphate of baryta, substantially as
herein described.