Improvements in the Treatment of Zinc Plates to be used as Substitutes for Lithographic Stones.
Year: 1893

page_text: Date of Application, 2nd May, 1893
Complete Specification Left, 2nd Feb., 1894-Accepted, 17th Mar., 1894
PROVISIONAL SPECIFICATION.
Improvements in the Treatment of Zinc Plates to be used as
Substitutes for Lithographic Stones.
We, EDWIN FORREST, of Lune Villa, Beaconsfield Road, New Southgate,
Lithographic Printer, and FRIEDRICH LOUIS HERMANN BUCHOLZ, of
16 Battledean Road, Highbury Fields, Compositor, both in the County of
Middlesex, do hereby declare the nature of this invention to be as follows:-
of water.
-
In carrying this invention into effect we procure zinc plates, as pure as can be
obtained commercially, and we pass them between highly polished cold rollers in
order to remove any inequalities or marks on the surface. The plates are then placed
in a bath of nitric acid and water in the proportion of 1 part of acid to 100 parts
This brings to the surface of the zinc, a blackish mass containing
impurities, which mass is removed by well washing with water and scouring with
pumice powder and a hard brush. The plates are placed in the acid bath and are
subjected to the same process of washing and scouring three or more times. Each
time it is found that the blackish mass is less and at the third or fourth operation
it is found that the solution of nitric acid and water no longer produces any
appreciable amount of the said blackish mass. The plates are then dried and are
subjected to the sand blast process in order to produce a grained surface. When
this has been completed the plates are placed in a bath composed of 4 parts of
nitric acid,
part of phosphoric acid, and 500 parts of water, after which they
are well washed. The plates are placed a second time in the said bath composed
of nitric acid, phosphoric acid and water and are again well washed.
cases we subject the plates a third time to this last mentioned process. The plates
are finally washed with a weak solution of alum composed of 1 part of alum to
50 parts of water, after which they are dried and are then ready for use.
In some
The plates produced by our process are porous and absorptive and sensitive to
grease and of a similar nature, for printing purposes, to lithographic stone and are
light in color, all of which qualities are very desirable.
E. FORREST,
F. L. H. BUCHOLZ,
By Harris & Mills,
23, Southampton Buildings, London, W.C., Agents.
COMPLETE SPECIFICATION.
Improvements in the Treatment of Zinc Plates to be used as
Substitutes for Lithographic Stones.
We, EDWIN FORREST of Lune Villa, Beaconsfield Road, New Southgate,
Lithographic Printer, and FRIEDRICH LOUIS HERMANN BUCHOLZ, of
16 Battledean Road, Highbury Fields, Compositor, both in the County of
Middlesex, 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 invention has for its object improvements in the treatment of zinc plates to
be used as substitutes for lithographic stones with a view to rendering them more

page_text: suitable and effective than zinc plates treated or prepared in any of the modes
heretofore adopted.
In carrying this invention into effect we procure zinc plates, as pure as can be
obtained commercially, and we pass them between highly polished cold rollers in
order to remove any inequalities or marks on the surface. The plates are then
placed in a bath of nitric acid and water in about the proportion of 1 part of acid
to 100 parts of water. This brings to the surface of the zinc, a blackish mass
containing impurities, which mass is removed by well washing with water and
scouring with pumice powder or such like material and a hard brush.
The plates are placed in the acid bath and are subjected to the same process of
washing and scouring three or more times. Each time it is found that the blackish
mass is less and at the third or fourth operation it is found that the solution of
nitric acid and water no longer produces any appreciable amount of the said
blackish mass. The plates having by the aforesaid process become absorptive
and all matters deleterious to lithography extracted therefrom are dried and are
subjected to treatment by the sand blast process in order to produce a grained
surface. When this has been completed the plates are placed in a bath composed
of about 4 parts of nitric acid, 1 part of phosphoric acid and 500 parts of water,
after which they are well washed in water.
The plates are placed a second time in the said bath composed of nitric acid,
phosphoric acid and water and are again well washed in water.
If required we subject the plates a third time to this last mentioned process of
of immersion in a solution consisting of nitric acid, phosphoric acid and water and
subsequently washing.
In some cases that is to say when fine grained plates are required, instead of
submitting the plates to a bath composed of nitric acid, phosphoric acid and water,
we place them in a bath consisting of about 1 part of sulphuric acid to 100 parts
of water which latter bath in no way interferes with the grain.
The plates are finally washed with a weak solution of alum consisting of about
1 part of alum to 50 parts of water after which they are dried and are then ready
for use.
The plates produced by our process are absorptive and sensitive to grease and of
a similar nature, for printing purposes, to lithographic stone and are light in colour
and retain such light colour after being submitted to the aforesaid baths, all of
which qualities are very desirable.
We would here remark that we do not claim broadly the treatment of zinc plates
with acids to render them suitable for lithographic purposes as such has before
been proposed, but such process has not been carried out in the manner above
described nor has it been combined with the further treatment herein referred to
nor has it produced such good results as those obtained when working according to
our invention.
Having now particularly described and ascertained the nature of our said inven-
tion and in what manner the same is to be performed we declare that what we
claim is :-
1. The treatment of zinc plates to be used as substitutes for lithographic stones
by the following process namely repeatedly subjecting them to the action of a bath
composed of nitric acid and water, well washing and scouring them after each such
bath, and then submitting them to the action of a sand blast substantially as
herein described.
2. The treatment of zinc plates by the following process namely, repeatedly
subjecting them to the action of a bath composed of nitric acid and water, well
washing and scouring them after each such bath, submitting them to the action of
a sand blast, subjecting them one or more times to a bath composed of nitric and
phosphoric acid and water, again well washing them in water then washing them
with a weak alum solution and finally drying them substantially as herein described
and for the purpose stated.

page_text: 3. The treatment of zinc plates to be used as substitutes for lithographic stones
by the combined processes substantially as herein described.
Dated February 2nd 1894.
EDWIN FORREST,
FRIEDRICH LOUIS HERMANN BUCHOLZ,
By Harris & Mills,
23, Southampton Buildings, London, W.C., Agents.