Improvements in the Production of Semi-transparent Marks or Designs on or in Paper by Means of Gelatine Relief Printing.
Year: 1889

page_text: Date of Application, 29th May. 1889-Accepted, 6th July, 1889
Improvements in the Production of Semi-transparent Marks or
Designs on or in Paper by Means of Gelatine Relief Printing.
I JACOB HUSNIK, Professor in Vinohrady, Prague, Bohemia, do hereby declare the
nature of my said invention and in what manner the same is to be performed, to
be particularly described and ascertained in and by the following statement :-
$
Whereas semi-transparent prints (or water-marks) in paper have sometimes been
made by means of matrices formed of thread. The design is traced on a piece of
stout paper in single lines. Upon these lines threads are attached by means of glue
or in any other suitable manner. Such matrices are ready for use, when sufficiently
dried. When using them they have to be pressed against the paper to produce the
water marks. Such figures however are necessarily very rough and inartistic, it being
impossible to produce fine lines and dots with threads.
The object of my invention is the production of water marks in paper by means of
gelatine reliefs, which reproduce the finest details of outlines or shaded figures in a
very superior manner. The reliefs are prepared by photography upon a sheet of stout
paper. The finest water marks being obtained therefrom by merely pressing them
upon the paper.
For a drawing in outline I either trace the drawing on a sheet of paper and take
therefrom a negative by photography, which negative is copied upon a film of
chromated gelatine. Or I engrave the drawing in a film upon glass with a needle or
graver and copy the same directly upon a film of chromogelatine.
.
When a shaded figure is required it is engraved in a film upon glass so as to
appear transparent. After having been copied by photography the engraved lines
leave plastic traces upon the chromogelatine. In pressing them against the paper
they produce semi-transparencies. It is necessary therefore to trace the lights only
and not the shaded parts when preparing such shaded figures. This may be effected
either upon paper or glass when preparing the drawing upon paper or any non-
transparent material, I cover the same with a strong film of chalk. The surface
has then to be thoroughly blackened with Indian Ink. I engrave the image in the
black ground by tracing the lights only, and leaving the shaded parts untouched.
Each touch of the needle or graver produces a line or a dot and the drawing
appears in white lines upon a black ground.
The drawing must then he photographed. A positive upon glass is taken from the
negative. The positive is copied upon chromogelatine. The lines which are meant
to appear finally raised are transparent in the drawing upon glass.
The films of gelatine may be prepared in any known way. But I prefer the
following method :-
1 kilogramme of soft gelatine is mixed with 250 cubic centimètres of glycerine
and 6 litres of water. When this is dissolved it is afterwards filtered. A sheet
of stout paper which has been immersed in water for about five minutes is then
stretched upon a plate of glass, horizontally, and small rims are formed on the
edges.
A layer of about three quarters of a millimetre thick of the gelatine
solution is then poured upon the paper. After sufficient hardening of the gelatined
sheet it is hung up to dry. Sheets thus prepared can he kept in store for years
ready for use at any time.
The preparation of the gelatine reliefs which I prefer is as follows:-
The sheets of gelatine just mentioned are to be placed for 10 minutes in a solution
of 1 part of bichromate of kalium, 25 parts of water and sufficient caustic aminonium
to render the bath yellow. The sheet is then spread upon glass which has been
covered with a film of wax in a similar manner to that practised with the so called
pigment papers. This must be dried in the dark. The sensitive sheet must be copied

page_text: under the negative upon glass, or in the case of a shaded figure under the positive
upon glass.
The drawing appears of a brown color upon a light yellow ground. The copy is
laid upon a plate of zinc or other suitable material, and a concentrated solution of
bichromate of natrium (17.8) is poured upon it. The sheet has to be rubbed with the
said solution by means of a brush, or in any other manner, so as to remove the
superfluous gelatine from the paper. The drawing then remains upon the
paper in
raised lines and dots. The relief thus obtained must then be washed and dried. It is
then ready for use.
Having now particularly described and ascertained the nature of my said inven-
tion and in what manner the same is to be performed I declare that what I
claim is :-
1. The method of producing semi-transparent marks or designs on or in paper, by
pressing the same with raised matrices forined with chromo-gelatine, substantially as
hereinbefore described.
2. The improvements in the production of semi-transparent marks or designs on or
in paper, by means of gelatine relief printing, substantially as hereinbefore described.
P1 964 M 1000
GEO. DOWNING,
s, Quality Court, London, W.C., Agent for Applicant.
GEO.
DOWNING,
s, Quality Court, London, W.C., Agent for Applicant.