Improvements in the Preparation of Printing Surfaces.
Year: 1887

page_text: Date of Application, 1st Jan., 1887.
Complete Left, 6th July, 1887.
Complete Accepted, 13th Sept., 1887.
PROVISIONAL SPECIFICATION.
Improvements in the Preparation of Printing Surfaces.
I, JAMES HUSNIK, Professor in Vinohrady, Prague, Bohemia do hereby declare
the nature of my said invention to be as follows:-
My invention consists in an improved method of manufacturing glue plates
(reliefs) to be used for the printing press, either directly or when electrotyped.
Glue or gelatine plates prepared by photography are not unknown in our days.
But these plates cannot be used for the printing press as they are, neither directly,
nor electrotyped, the lines being not high enough. In the process now in use, the
chromated glue plates are developed by warm water (or by another warm liquid)
from the back-side, i.e. from the side which has not been exposed to the light.
In my new process this development is caused from the front side which has been
exposed to light. I do not develope it through a warmed liquid, but through a cold
glue-dissolving liquid, by rubbing the exposed side of the plate with such a cold
liquid by means of a brush or any appropriated lap.
With my method I obtain glue-plates which can directly be used for printing say
of thirty thousand copies by the printing press, without injury. The copies are
hardly to be distinguished from the originals, each line and point being as sharp and
regular in the copies as in the original.
I prepare electrotypes from my glue-plates in using matrices of natural wax, or by
any other of the known methods.

page_text: I, JAMES 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:-
My invention has for its object the production of reliefs on chromated gelatine
plates, by means of photography; in such a manner, that they may be used for
printing, in the printing press, either directly or after electrotyping.
In carrying out my invention I proceed as follows. I take what is known as
chromated gelatine plates, and expose them to the light obtained from negatives of
drawings, pictures or photographs, so as to affect these plates. Then I develope such
a plate on the front side, i.c. on the side which has been exposed to the light, and not
on the back, i.e. not on the side, which has not been exposed to the light. I do not
develope it with warm liquids, but with such liquids, which dissolve gelatine at the
usual temperature. This is done by brushing or rubbing the gelatine plate on the
side which has been exposed with any suitable material such as sponge, or with a
brush tipped in cold liquids.
I also mount such plates, before developing them, by attaching the non-exposed
side, i.e. the back, upon hard level plates of resisting materials, as for instance zinc,
wood, or other material. This is effected by means of guita-percha or other elastic
substance, which adheres firmly, it having for its object the formation of an elastic
backing for the printing plate.
A great number of liquids are known, which dissolve gelatine at the usual
temperature, any one of which may be used for the above purpose. But I prefer to
use a saturated solution of alkaline bichromates thus applying a description of such
salts, not hitherto applied for such purpose. Such solutions do more than dissolve
the gelatine, upon which the pencil of light did not fall. They deepen and strengthen
the relief, and the development takes place more thoroughly.
I also stop the development before the finest dots and lines become destroyed or
affected by its action. I let the plates dry, and cover the lights with a solution of
printer's black in terebinthine, by means of a fine hair pencil, and I then expose it
for the second time to the action of light. The relief having absorbed a quantity of
alkaline bichromates, it is very sensitive. It hardens and strengthens not only on
the surface, but especially also on the flanks of each line and dot. It can be therefore
developed to any desired depth after having taken off the blacking, especially if care
has been previously taken to cut out the lights with a sharp knife.
In some other similar methods the development may also be stopped in time, the
light being fitted with gum arabic, for instance, and the relief exposed a second time.
The bi-chromates in the high parts of the relief are all decomposed through the action
of the light. And in case a small portion of the alkaline bichromates should remain
without being decomposed, then it must be decomposed afterwards, through the
action of acetic acid and it will be washed out by the process of development. It is

page_text: known that acids decompose chromated salts in the presence of organic substances.
It is evident therefore that no further strengthening of the relief can be attained in
that way. And in case some trace of the chromates have remained, then the filling up
of the lights with a coloured plastic mass would cover the flanks of the dots and lines,
so that no light would affect and strengthen it on a second exposure.
In the manner above described I prepare plates for the printing press, which will
print a hundred thousand copies. Electrotypes from such gelatine plates can be
prepared by using matrices of wax, and a fine graphite, or by any other of the usual
methods.
I do not use any particular method in the direct reproduction of pictures oil-
paintings and photographs. It may be mentioned that I use a fine gauze, which is
put in front of the camera, and through which the photograph is taken, if the original
is not drawn or otherwise prepared in sharp lines or dots. Such photographs taken
through fine gauze are known, and that process is in general use at the present time
for autotypes and similar purposes.
Having now particularly described and ascertained the nature of my said
Invention, and in what manner the same is to be performed, I declare that what I
claim is :-
1. In the preparation of plates for the purposes aforesaid, the method of rubbing
or brushing sensitised gelatine plates, and more particularly chromated gelatine
plates, on the side which has been exposed to light, with solutions which dissolve
gelatine at the ordinary temperature, for the purpose of preparing such reliefs, and
which are sufficiently deep and durable for the printing press, and especially in
developing them by solutions of alkaline bichromates, which not only dissolve the
unexposed gelatine, but which harden and deepen the relief, substantially as herein
before described.
2. In the preparation of plates for the purposes aforesaid, stopping the development.
with solutions of alkaline bichromates, before the finest dots and lines are obliterated;
drying and covering the light with a solution of printer's black in terebinthine, close
to the drawing and exposing for the second time, for the purpose of strengthening and
deepening the sensitive plate, so that it can be developed to any desired depth,
substantially as herein before described.
3. In the preparation of plates for the purposes aforesaid, mounting sensitised
gelatine plates, before their development, on hard plane plates, by means of gutta
percha or other adhesive and elastic substances, on the side which has not been
exposed, and before the said rubbing or brushing is performed, substantially as herein
before described.