Year: 1886

page_text: Date of Application, 3rd June, 1886.
Complete Left, 23rd Feb., 1887.
Complete Accepted, 25th Mar., 1887.
I, HERMANN EMIL PAUL DORN of Leipzig in the Empiro of Germany Munu-
facturer, do hereby declare the nature of this invention to be as follows :-
This invention relates to a method of etching plates of any metal by means of an
acid and also by an electric current, by the use of which the plates are better and
more quickly etched than by hitherto known processes.
The process is performed as follows;The Plate to be etched, which may be of any
suitable metal or alloy is provided with the drawing to be etched and the places
which are intended to remain elevated are covered with a good insulating layer
protecting the metal from the effect of the electric current as well as of the acid
employed. This being done, the plate is connected with one wire of a galvanie
battery. The wire from the other pole of the battery is connected with another
metal plate or well conducting carbon plate, the surface of which is equal to that of
the plate to be etched, The two plates are then arranged parallel to one another but
without touching, in a bath of a diluted acid sufficiently strong to chemically attack
the metal of the plate to be etched.
The vessel containing the acid bath may be of such material as to serve as one
electrode.
The galvanic current passes between each non-insulated place of the plate to be
etched, and the nearest opposite place of the other plate, whereby the chemical action
of the acid on the metal is considerably increased, and the etching therefore accelerated,
the chemical action assuming at the same time the direction of the galvanic current
whereby the etching is produced vertically and uniformly without the acid corroding
the metal under the insulating layer or attacking the metal from the sides of the
etchings.
When the etching has continued to a suitable depth, the plate is removed.

page_text: I, HERMANN EMIL PAUL DORN of Leipzig, Germany, Manufacturer, 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 method of etching plates of any metal, by means of an
acid and also by an electric current by the use of which, the plates are better and
more quickly etched than by hitherto known processes.
The process is performed as follows :-
:-
The plate to be etched which may be of any suitable metal or alloy, is provided
with the drawing to be etched; and the places which are intended to remain elevated
are covered with a good insulating layer protecting the metal from the effect of the
electric current as well as of the acid employed.
This being done the plate is connected with one wire of a galvanic battery. The
wire from the other pole of the battery is connected with a negative metal or carbon
plate, the surface of which is preferably equal to that of the plate to bo etched.
The two plates are thon arranged parallel to one another but without touching, in a
bath of a diluted acid, sufficiently strong to chemically attack the metal of the plate
to be etched.
The vessel containing the acid bath may be of such material as to serve as the
negative plate.
The galvanic current passes between each non-insulated place of the plate to be
etched and the negative plate, whereby the chemical action of the acid on the metal is
considerably increased and the etching therefore accelerated, the chemical action
assuming at the same time the direction of the galvanic current, whereby the etching
is produced vertically and uniformly, without the acid corroding the metal under the
insulating layer or attacking the metal from the sides of the etchings.
When the etching has continued to a suitable depth the plate is removed.
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 process for etching metal consisting in employing the metal plate to be etched
and a negative plate of metal or carbon as electrodes of a galvanic current in an
acid bath.
Dated this 23rd day of February 1887.
H. E. P. DORN.
Pp. Herbert & Co.,
67, Strand, W.,
Agents to Applicant.