Surface Printing Plates.
Year: 1892

page_text: Date of Application, 7th June, 1892-Accepted, 9th July, 1892
COMPLETE
SPECIFICATION.
Surface Printing Plates.
We JOHN MULLALY, of 223 East 49th Street, and LATHROP LAMB BULLOCK,
of 39 Broad Street, both in New York City, in the County of New York, and
State of New York, United States of America, Gentlemen 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 :-
Our invention relates to surface printing plates having a surface of pure or sub-
stantially pure aluminium, as described and claimed by us in our United States
Patent No. 459,239 dated September 8th, 1891.
An important discovery which we have made and one which clearly distinguishes
the difference between our use of the aluminium plate and the use of the stone, is
that we are enabled to regulate the density of the plate, and consequently its
porosity during its manufacture, with relation to the work to be performed on it.
Thus a finer grade of work can be produced on a plate of comparatively greater
density than that desirable for work of a coarser nature, and this feature of variable
density in a measure may be considered independently of that of the preparation of
the surface by graining. It is true that both the density of the plate and the
coarseness or fineness of the graining imparted to the surface both act in conjunc-
tion in affecting the quality or grade of the plates, but the variation in density is of
paramount importance in regulating the actual degree of porosity upon which the
absorbent quality of the plate mainly depends.
Our present invention consists essentially in adapting the absorbent quality or
porosity of our aluminium surface printing plates to the special character and
requirements of the designs to be imposed thereon by regulating the density of said
plates. This we accomplish by compressing the aluminium plate or surface more
or less by mechanical means as by rolling &c. The comparatively light spongy
nature of the metal readily admits of this treatment, and the closeness or texture of
the plate and printing surface can be thus varied or regulated with uniformity and
precision.
In the accompanying drawings we illustrate the embodiment of our invention
in practical form, although we do not confine ourselves to any special form or
construction of parts, since, it is obvious that various modifications in detail may
be introduced without departing from the essential spirit of our invention.
Figure 1, is a plan of a flat printing plate, with aluminium printing surface upon
which a design has been imposed;
Figure 2, an edge view of Figure 1 ;
Figure 3, a sectional view indicating a plate of metal or other suitable material
provided with a facing of aluminium deposited by electrolysis, the thickness of the
aluminium being exaggerated for purpose of illustration;
Figure 4, a similar view showing a sheet of aluminium backed with metal or other
suitable material;
Figure 5, a sectional view of a cylindrical printing roller formed with a printing
surface of aluminium ;
Figure 6, is an isometrical view of a comparatively thin sheet or printing plate
of aluminium, unsupported by any backing and therefore sufficiently flexible to
adapt itself readily to pressure during printing.
The printing plate A, as a whole may be formed or built up in any suitable or
well known manner provided it is formed with the facing a, of aluminium. Thus
the facing a, may be afforded by the use of a comparatively thick plate a', of
aluminium attached to a platen or base 6; or a comparatively thin layer (a',
ID 7

page_text: Figure 3) of aluminium may be applied to the base or platen b, by electro-
deposition.
Again, a thin plate of aluminium may be secured to the base or platen b, by any
suitable mechanical means of attachment as illustrated in Figure 4, or to the
surface of a rotary printing roller 6', indicated in Figure 5; or a simple thin
sheet of the metal may be used for the printing plate, which form is especially
effective in some forms of printing, as for instance for use in the band press.
In all the constructions indicated as well as in the case of others that may be
desirable to comply with the requirements of special use the essential feature is the
layer or plate a', of aluminium affording a printing surface a, of that metal, and all
questions of construction and application are secondary to that.
The density of the sheet or plate a', of aluminium, or in which aluminium pre-
dominates is regulated mechanically, by compression, as by rolling, hammering &c.,
or by burnishing the surface to decrease its porosity.
It is to be understood that while we use and claim substantially pure aluminium
for our improved surface printing process we do not limit ourselves to the pure
article as any compound plate in which aluminium predominates may be used
if desirable without departing from the essential spirit of our invention.
Having now particularly described and ascertained the nature of our said
invention, and in what manner the same is to be performed, we declare that what
we claim is ;
First. The process of manufacturing aluminium surface printing plates of
different prescribed grades of porosity, consisting in regulating the density of the
aluminium plates mechanically according to the character of the designs to be
imposed thereon, substantially in the manner described.
Second. The herein described plate for use in surface printing, consisting of a
plate in, which aluminium predominates, having a suitable design imposed thereon,
said plate being compressed to a prescribed density, substantially as described, for
the purpose of adapting it to the nature and requirements of the design imposed
thereon.
Dated this 7th day of June 1892.
FELL & WILDING,
1, Queen Victoria Street, London, E.C., Agents for the Applicants.