Improvements in the Employment of Photographic Gelatine Reliefs for the Production of Gelatine Images.
Year: 1899

page_text: Date of Application, 30th Oct., 1899-Accepted, 30th Dec., 1899
COMPLETE SPECIFICATION.
Improvements in the Employment of Photographic Gelatine Reliefs
for the Production of Gelatine Images.
I, WILLIAM HUMPHREY WHEATLEY, of the Firm of Wheatley and Mackenzie,
Engineers and Patent Agents, of 40, Chancery Lane, in the County of London,
do hereby declare the nature of this invention a communication to me from
abroad by the Firm of Heimsoeth and Company, of 104, Hansaring, Cologne, in
the Empire of Germany, Merchants-and in what manner the same is to be
performed to be particularly described and ascertained in and by the following
statement:—
The moulds for printing by the Woodbury process have hitherto been pro-
duced by first forming a relief, by washing a chromated gelatine film and after-
wards making a metal mould therefrom. The washing of the chromated gelatine
film, as also the preparation of the metal mould, is associated with many
technical difficulties and much loss of time. The greatest difficulty however
in connection with this method is that of obtaining perfectly even moulds.
As a matter of fact, the process has been found to be too expensive and tedious,
and therefore could only be employed commercially to a limited extent.
•
The production of moulds by my correspondents' method on the contrary
can be effected rapidly and at little cost.
In carrying out this invention a plate of plate-glass is covered with a sen-
sitive film of gelatine and exposed under a negative or a positive, and the gelatine
film converted by washing into a relief, this last mentioned relief forming the
printing mould.
In order that the gelatine ink may not remain adhering to the mould, it must
be saturated in a suitable manner with oil or grease. As the relief completely
soaked with water would repel the oil or grease, and at the same time care must
be taken not to conceal the finer details, only a decomposed layer of oil or grease
must be put on. This must be so effected that the gelatine, which is not very
resistant, may be preserved against pressure or friction.
The relief is therefore, for a certain time, placed in a bath consisting of a
solution of soap and water, and then in a 10% solution of chromate of alum or
of an acid. The soap in the gelatine film will be hereby decomposed and the
gelatine completely saturated there with. On the surface a scarcely perceptible
trace of grease will remain which, however, owing to its consistency, separates
the gelatine ink from the relief completely. By a further treatment with oil,
the residue of grease can be strengthened.
In printing processes with metal, rosin, or other hard moulds, the latter
hitherto had to be vigorously rubbed with oil with a flannel rag. This rubbing
in of oil had to be repeated after every printing; consequently the delicate
outlines of the relief were dulled by the frequent rubbing, and the prints
wanting in sharpness. In my correspondent's process the mould is steeped
with oil and this oiling needs only to be repeated after a considerable number

page_text: of printings. As the moulds are not continuously rubbed with oil, they last
longer than those formerly used and made of metal.
As the relief is formed directly on a plate of plate-glass, and remains thereon
during the printing, a permanent evenness is insured in the moulds, and thereby
a novel, rapid and inexpensive method of printing from gelatine moulds created,
as hitherto it has not been known that reliefs in gelatine could be employed for
this purpose.
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:-
The employment of a gelatine relief, produced by a photographic process, for
the production of gelatine images, in which the gelatine relief is saturated with
a fatty substance or a rosin soap, so that the cast and subsequently congealed
gelatine ink can be removed together with the material, on which it is printed.
Dated this 30th day of October 1899.
WHEATLEY & MACKENZIE,
40, Chancery Lane, London, W.C., Agents.