Improvements in the Manufacture and Production of Plates for Printing Purposes.
Year: 1897

page_text: Date of Application, 27th July, 1897-Accepted, 28th Aug.,
1897
COMPLETE SPECIFICATION.
Improvements in the Manufacture and Production of Plates for
Printing Purposes.
I, CHRISTIAN SCHOLZ, of Mainz, in the Empire of Germany, Engineer, 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:-
The object of my invention is to prepare the surfaces of aluminium or other
metal plates used in substitution for lithographic stones for printing purposes
in such a manner that better results are obtained than are obtainable from plates
prepared as hitherto.
The production of a uniform and effective granulation on the surface of litho-
graphic stones which will properly receive a drawing and can be afterwards
properly inked and printed from, presents no difficulty but with aluminium or
other metal plates whereon the granulation is effected by means of the sand blast
or other suitable means it has not hitherto been possible to obtain on the surface
thereof a granulation capable of receiving a drawing so that a clear and exact
print of the drawing can be obtained from the plate. This difficulty is probably
due to the projections of the granulation being tod pointed to permit a sufficient
quantity of the lithographic crayon or drawing material used, to adhere to the
actual printing face of the plate, only small particles of the lithographic crayon
or drawing material adhering to the points of the projections tormed by the
granulation while other particles of such crayon or material attach themselves
to the sides of such projections and do not appear in the print because, the inking
roller only comes in contact with and inks the points of the said projections,
leaving the other portions of the drawing uninked.
By my invention I entirely overcome this defect and provide a plate from which
a print can be obtained which is an exact reproduction of the drawing made on
the plate.
My process consists in first producing granulation on a metal plate, by the sand
blast, or other suitable means, and in afterwards subjecting the grained plate to
compression applied by rolling, hammering, pressure, or other suitable means;
so that the points of the projections of the granulation are pressed down and
blunted, or spread out, and caused to present on the surface of the plate, a uniform
series of small surfaces which are not pointed, and which receive and hold the
drawing firmly and constitute a uniform dense granulation with projections which
take the lithographic crayon, or drawing material, and allow of all particles
thereof being inked and appearing in the prints taken from the said plate. The
pressing down of the points of the projections of the granulation can be very
conveniently effected by passing the plate between rolls, the pressure of which
upon the plate can be regulated according to requirements as the points of the
projections of the granulation will be more, or less, flattened according to the
amount of pressure applied, so that it is practicable, by this means, to adapt the
grained surface of the plate to any special character of drawing to be produced
upon it.

page_text: After the treatment described, the grained plate is cleaned which may be done
in the usual manner and is then ready to receive the drawing and to be inked
and printed from, which also may be done in the usual manner.
Having now particularly described and ascertained the nature of my said in-
vention and in what manner the same is to be performed I declare that what I
claim is:-
-
تھا
1. The preparation of aluminium or other metal plates for printing, consisting
in producing on the plate a grained surface, and then subjecting the plate to
pressure whereby the pointed projections of the granulation at the surface of the
plate are flattened, substantially as, and for the purpose, herein before described.
2. As a new article of manufacture a printing plate produced as hereinbefore
described and claimed.
Dated this 27th day of July 1807
JOHNSONS & WILLCOX,
47 Lincoln's Inn Fields, London, W.C., Agents.