Year: 1887

page_text: Date of Application, 19th July, 1887
Complete Left, 3rd Apr., 1888
Complete Accepted, 4th May, 1888
I HERMANN SCHOEMBS of Offenbach on the Main Germany do hereby declare the
nature of this invention to be as follows:-
This invention relates to a process of preparing zincographic printing plates so as
to impart to them the porous quality peculiar to the lithographic stone.
1 first place the mechanically cleaned or grained zinc plates in a mixture of nitric
and sulphuric acids for a short time. The surface of the zinc is rendered finely
crystalline or porous by the solvent action of the sulphuric acid thus rendering it
more suitable for the reception of the colour whilst the nitric acid oxidizes the nascent
hydrogen whereby a more uniform action of the sulphuric acid is ensured.
The plates are then removed from the bath and cleaned by rinsing off with water
the adhering acid, as also the carbon separated out by the action of the acid they are
then rinsed with a dilute solution of an ammonia salt (other than ammonium sulphide)
preferably ammonium chloride and dried.
The plates are to be washed off with clean water just before being used in order to
dissolve the double salt formed.
The ammonia salt effects the conversion of the basic zinc carbonate formed by the
action of the atmosphere upon the moist zinc plate into a readily soluble double salt of
zinc and ammonium which is easily dissolved by washing the plate as directed
with clean water thus laying bare the porous pure metallic zinc surface to receive the
printing colour.
H. SCHOEMBS.
By A. M. & Wm. Clark,
53, Chancery Lane, London,
Patent Agents.

page_text: An Improvement in Preparing Zincographic Printing Plates.
I, HERMANN SCHOEMBS, of Offenbach-on-the-Main, Germany, 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 :-
This invention relates to a process of preparing zincographic printing plates, so as
to impart to them the porous quality-peculiar to the lithographic stone.
I first place the mechanically cleaned or grained zinc plates in a mixture of nitric
and sulphuric acids for a short time. The surface of the zinc is rendered finely
crystalline or porous by the solvent action of the sulphuric acid, thus rendering it
more suitable for the reception of the color whilst the nitric acid oxidizes the nascent
hydrogen whereby a more uniform action of the sulphuric acid is ensured. The plates
are then removed from the bath and cleaned by rinsing off with water the adhering
acid, as also the carbon separated out by the action of the acid, they are then rinsed
with a dilute solution of an ammonia salt (other than ammonium sulphide) preferably
ammonium chloride, and dried.
The plates are to be washed off with clean water just before being used in order to
dissolve the double salt formed. The ammonia salt effects the conversion of the basic
zinc carbonate formed by the action of the atmosphere upon the moist zinc plate into
a readily soluble double salt of zinc and ammonium which is easily dissolved by
washing the plate as directed with clean water, thus laying bare the porous pure
metallic zinc surface to receive the printing color.
Having now particularly described and ascertained the nature of the said
invention and in what manner the same is to be performed, I declare that what
I claim is ;-
1. The herein described process of producing zincographic printing plates with a
fine porous surface by subjecting them to the action of nitric and sulphuric acids and
afterwards to the action of an ammonium salt, as and for the purpose specified.
2. As a new article of manufacture, a zincographic printing plate produced as
above described, having a porous surface like that of a lithographic stone.
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