Improvements in Photo-etching.
Year: 1891

page_text: Date of Application, 26th May, 1891
Complete Specification Left, 21st Oct., 1891-Accepted, 21st Nov., 1891
PROVISIONAL
SPECIFICATION.
Improvements in Photo-etching.
I, BENJAMIN CONSTANT LE MOUSSU of 23" Wilmington Square, Clerkenwell, in
the County of Middlesex, Photo 'Etcher, do hereby declare the nature of. this
invention to be as follows:-
This invention relates to the reproduction of photographs, paintings, drawings and
the like in what is known as.tone process for printing in typography, lithography
and the like and by it I am enabled to obtain the best results with the great saving
of time and labour over the existing processes.
The usual process at present employed for attaining the same end as is con-
templated by the present invention consists in the employment of a printed bitamen,
albuinen or, transferred.image fully developed with an intense screen in front of the
sensitized plate in the camera so as to break the heavy tones, the result being a
general tone over the full lights and a faint flat image on the metal. The treat-
ment required to bring out the lights, tones and definitions involves the expenditure
of a great-amount of labour to roll, resin, burn, stop and repeatedly fetch and
subsequently, burnish and complete with roulettes and gravers the plate, not
unnaturally. resulting in the destruction of the natural artistic feeling and the purity
ofithe original subject.
•
In carrying out my invention I proceed on the same general lines starting with
purified bitumen dissolved in benzole as a sensitive coating on zinc copper or 'steel
plates to be exposed under a divided negative or positive of the subject. "The great
difference between the existing process and my improved process consists in this
that while, with the existing process the photographic part of the process is first
completed and then the etching is carried out, in my improved process the photo-
graphing and fetching, proceed concurrently, or practically simultaneously. Thus
the first development which is only partial, then the first etching which also is only
partial; then the second development followed by the second etching, and so on
until.the process is completed, the last etching leaving a pure artistic and faithful
image etched deep or in relief in the plate, the destructive and costly manipulations
above referred to having been entirely dispensed with.
.
Dated this 26th day of May 1891.
W. P. THOMPSON & BOULT,
Agents for the Applicant.
COMPLETE. SPECIFICATION.
Improvements:in Photo-etching.
BENJAMIN CONSTANT LE Moussu, of 23 Wilmington Square Clerkenwell in
the County of Middlesex, Photo-etcher, 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 :—
"tone
"
This invention relates to the reproduction of photographs, paintings drawings and
the like, in what is known as
process for printing in typography lithography
and etching proper, and by it I am enabled to obtain the most natural results with
a great saving of time and labour over the existing processes. The usual process,
at present employed for attaining the same end as is contemplated by the present
invention consists in the employment of a printing bitumen, albumen, gelatine or
other suitable substance or transferred image fully developed printed from an
under exposed negative or positive obtained with an intense screen in front of the

page_text: sensitized plate in the camera, so as to break the heavy tones, the result being a
general tone over the full lights and a faint flat image on the nietal. The treatment
required to bring out the lights, tones and definitions involves the expenditure of a
great amount of labour to roll, resin burn stop, and repeatedly etch and subse-
quently burnish and complete the plate with roulettes, gravers and burnishers, not
unnaturally resulting in the destruction of the natural artistic feeling and purity of
the original subject.
In carrying out my invention, I proceed on the same general lines, but the great
difference between the existing process and mine consists in this:-that while with
the existing process the developing of the bitumenized plate is first completed and
then the etching is carried out, in my improved process the developing and etching
proceed concurrently or practically simultaneously.
Now according to this invention, I take a polished zinc copper or steel plate and
coat the same with a solution of purified bitumen dissolved in benzole to which
chloroform may be added.
The bitumenized plate when dry is exposed to the action of light under the
negative or positive of the original picture image or object to be reproduced, which
negative or positive has been obtained by interposing a lined or grained screen in
front of the sensitive plate in the camera in the usual way, or by artificially or
chemically graining any undivided negative or positive.
When the bitumenized plate has been sufficiently exposed, the image is partly.
developed by means of turpentine or other usual hydrocarbon or hydrocarbons.
The plate is then etched in a bath composed of a strong solution of nitric or other
suitable acid and water, the plate is then washed in clean water and dried,
and the image still further developed with turpentine or hydrocarbon and the plate
again etched in a weaker solution of acid and water, and if necessary, after again
washing and drying the plate, the image is still further developed, and the plate
again etched till the deeper shadows or lights stand well out.
In case the first developing has been excessive, it will be necessary to correct
this defect by inking the plate between each etching, the process then being as
follows:-
After the image on the bitumenized plate has been partly developed as above
described, the plate is etched in a bath composed of a strong solution of nitric acid
or other suitable acid and water. The plate then inked by rolling to protect the
edges and sides of the etched portions, and if necessary resined and again etched.
This inking and etching is continued till the requisite depth of etching for the high
lights or shadows (according to whether the image has been obtained from a
negative or positive) is attained, the other portions of the plate being protected
from the action of the acid by the undeveloped coating. The plate is next cleaned
with turpentine or paraffin water and gum, the gum and water neutralizing the
developing action of the turpentine, and the image still further developed with
turpentine or suitable hydrocarbon and the plate again etched in a weaker solution
of acid and water, and if necessary the image is still further developed and the
plate etched, till the deeper shadows or lights stand well out.
In previous processes, it has been necessary to use a negative under exposed and
under intensified, but in my process I use a negative which has been fully exposed
and fully intensified, thereby obtaining a more effective and complete image on the
metal plate. The result of my process is a pure artistic and faithful image of the
original etched deep or in relief, the whole process only taking from thirty minutes
to an hour for its completion.
Having now particularly described and ascertained the nature of my said inven-
tion and in what manner the same is to be performed, I declare that what I
claim is':-
(1.) In the process of photo etching on metal, alternately partially developing
the image and partially etching the plate with one or more etchings between each
developing, substantially as hereinbefore described.

page_text: (2.) The improved process of photo etching, substantially as specified.
Dated the 20th day of October 1891.
ERNEST SALAMAN,
Patent Agent to the British and Foreign Patents and Trade Marks Society,
61 & 62, Chancery Lane, W.C., Agent for the Applicant.