A NEW OR IMPROVED PROCESS FOR OBTAINING VITRIFIABLE MONOCHROME OR POLYCHROME PHOTOGRAPHS
Year: 1881

page_text: A com-
PROVISIONAL SPECIFICATION left by Henri Adrien Bonneville at the
Office of the Commissioners of Patents on the 17th December 1881.
munication by Michel Gabriel Wolff, of Rue des Vinaigriers, Paris, France.
HENRI ADRIEN BONNEVILLE, of the British and Foreign Patent Offices, 8, Rue
de la Chaussée d'Antin, Paris, France, and 90 Cannon Street in the City of
London, Patent Agent. "A NEW OR IMPROVED PROCESS FOR OBTAINING
VITRIFIABLE MONOCHROME OR POLYCHROME PHOTOGRAPHS." A communication by
Michel Gabriel Wolff, of Rue des Vinaigriers, Paris, France.
The Invention relates to a new or improved process for obtaining vitrifiable
monochrome or polychrome photographs cheaply and rapidly.
To attain this object, a paper prepared with the following compound is used:
Fish glue
Gelatine
Vitrifiable colour
Water
-
-
about
-
"
1/3 OZ.
21 oz.
(10
(60
grammes)
grammes)
-
"
->
7 02.
/, to /, oz. (10 to 15
(180
"
"
-
about 1 oz.
about 4 oz.
9
This paper is sensitized in a solution of
Alkaline bichromate
Water
-
(3 grammes)
(100 grammes)
A certain quantity of alcohol may be added to facilitate the drying. The paper
is then ready to receive the light through a negative plate. After it has been in
long enough, which fact can be easily ascertained by the use of a photometer, the
proof is plunged into cold water, and placed on a temporary flexible support. For
certain surfaces it is preferable to convey the photographic image by means of a
pellicle either of gold beater's skin prepared with stearine, or of collodion; this is
the best method of procedure when the photograph has to be placed upon a rough
surface.
The photograph is then developed in warm water (about 35 degrees centigrade)
and afterwards washed in cold water. By this treatment, the proof still contains
some chromic salts which during the process would destroy the flux, and thus
prevent the colours from adhering, and make then dull and indistinct; moreover,
the chromic acid would stain the porcelain a nasty green colour; all traces of
Price 1

page_text: bichromate must therefore be destroyed without however, either dissolving or
cracking the gelatine, or disturbing the flux. For this purpose, the proof is dipped
in alcohol containing a few drops of chlorydric acid, and the photograph
immediately loses the yellowish tint imparted by the bichromate and presents a
most delicate appeurance. The photograph is then bathed in a weak solution of
alkali so as to neutralize the acid; it is then ready to be put on the article to be
decorated, which, however must be previously coated with a compound of fish glue,
gelatine, flux finely pounded, and water mixed in various suitable proportions.
After being dried, the conveying paper will be easily taken off, and the
photograph will be vitrified in a muffle furnace after the manner of the paintings
on enamelled porcelain.
By this method photographs of any article of the most delicate tint will be
obtained, showing monochrome objects, such as engravings, armory and statues in
their natural colour, polychrome objects will also be reproduced; for the latter
however, prepared papers of the same colours as those of the various parts of the
subject must be placed underneath the corresponding parts of the plate. The
said coloured papers will be placed in position either by means of the temporary
support, or directly upon the article to be decorated.
The effect produced by this combination of papers is that of a photograph in
striking colours which will easily be modified by covering it with a monochrome
photograph which increases the effect, though the latter operation is not necessary
-in-the-majority-of-cases.-
The proofs are touched up whilst they are on the temporary support as by this
means splendid effects are obtained upon both monochrome and polychrome
photographs by applying mineral colour to them; these colours may be prepared
with gelatine or other matters to give them body, and they can be made insoluble
before the photograph is conveyed. When gelatine is used it will be sufficient to
pass them through a solution of alum and water nixed in suitable proportions.
The colour may also be prepared with a liquid of an oily nature such for
instance as turpentine, but in this case, instead of passing the proof through a
solution of alum, it should have a thin coat of gelatine as a precaution, but it is
not always necessary. The proof will then be conveyed in the manner above
described,
It may be remarked that the colour used in touching up lies underneath the
photograph when the latter is conveyed to the article to be decorated, so that very
deep and even opaque colours may be used without concealing the smallest details,
and no matter how carelessly they are applied, they are toned down by the
photograph which also gives them form.
A distinct feature of the Invention is that the photographs can also be touched
up in the usual manner.