Process for Photographing in Colours.
Year: 1894

page_text: I NOVIDIUNAL DI MUIFICATION,
A Process for Photographing in Colours.
I, VICTOR MATHIEU, of No. 51 Berwick Street, Oxford Street, in the County
of Middlesex, Photographic Artist, do hereby declare the nature of this invention
to be as follows:-
:-
This invention relates to a process by which photographic pictures are produced
in colours more or less corresponding with those of the objects photographed, which
may be living objects such as persons, or inanimate objects such as landscapes or
pictures. For this purpose, several plates are prepared with different emulsions to
be used for taking several negatives of the object, suited for the different colours
that are to be reproduced. Usually three such plates are employed, one for
reproduction of blue, one for red and one for yellow.
An image is first taken on the plate prepared for blue the light being passed
through a bright yellow or orange glass screen, then the image is taken without a
screen or with a green screen on the plate prepared for red, and finally the image
is taken on the plate prepared for yellow, a light violet screen being employed.
These three negatives are developed in the usual way.
Coloured gelatine solutions are prepared, one coloured blue with Prussian blue,
another coloured red with carmine, and a third coloured yellow with yellow
chromium powder. With these solutions three moistened papers laid on glass are
coated, and when dry they are sensitised in a bath of potassium bichromate. The
three sensitised papers are then removed from the glass and are photographically
printed from their respective negatives, and the proofs are then placed, the gelatine
sides downwards, on glass plates which have been previously waxed and immersed
in cold water. The proofs adhering to the glasses are pressed by a roller to expel
surplus water and are then put in warm water; the papers are then peeled off and
the gelatine proofs are allowed to develop until the images are quite clear, whereupon
they are washed in cold water and dried. One of the three gelatine films is then
transferred from the glass to paper coated with gelatine, another is placed in
register on it, and the third is placed in register on the second, there being thus
three coloured images superposed on the paper, the whole forming a coloured
picture which can be glazed and mounted in the usual way. Instead of gelatine,
albumen, collodion, or other suitable substances giving transparent films, may be
employed.
Dated this 18th day of September 1894.
ABEL & IMRAY,
Agents for the Applicant.
I, VICTOR MATHIEU, of No. 51, Berwick Street, Oxford Street, in the County
of Middlesex, Photographic Artist, de 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 by which photographic pictures are produced
in colours more or less corresponding with those of the objects photographed, which

page_text: may be living objects, such as persons, or inanimate objects, such as landscapes, or
pictures. For this purpose, several plates are prepared with different films to be
used for taking several negatives of the object, suited for the different colours that
are to be reproduced. Usually three such plates are employed, one for reproduction
of blue, one for red and one for yellow.
An image is taken on the plate prepared for blue the light being passed through
a bright yellow or orange glass screen. The image is also taken without a screen,
or with a green screen, on the paper prepared for red, and it is also taken on the
plate prepared for yellow, a light violet screen being employed. These three
negatives are developed in the usual way. Instead of using coloured screens in
taking these negatives, the films may be suitably coloured as hereinafter described.
Coloured gelatine solutions are prepared, one coloured blue, another coloured
red, and a third coloured yellow. With these solutions three gelatine films are
prepared sensitised and photographically printed from their respective negatives,
and the proofs are suitably developed. One of the three gelatine films is then
transferred to paper coated with gelatine, another is placed in register on it, and
the third is placed in register on the second, there being thus three coloured
images superposed on the paper, the whole forming a coloured picture which can
be glazed and mounted in the usual way. Instead of gelatine, albumen, collodion
or other suitable substance giving transparent films may be employed.
Such being generally the nature of the process I shall now describe the
particular substances, proportions and methods of operating for producing coloured
photographs. A film for the negative plate to reproduce blue is prepared as
follows. In a dark room, in one vessel 10 grammes silver nitrate are dissolved in
100 grammes of distilled water. In another vessel 8 grammes potassium bromide
are dissolved in 100 grammes of distilled water and gramme of eosin is added.
Both solutions are slightly heated and the former is poured into the latter, and,
10 grammes liquor ammonia sp. gr. 880 being added, the mixture is thoroughly
agitated. It is then for six hours kept at a temperature of about 50° C. on the
water bath and afterwards poured into 10 times its weight of distilled water, and
after thorough agitation left to settle. When clear the water is slowly poured off
and to the material left in the vessel are added 10 grammes gelatine and
100 grammes of distilled water; the mixture is heated until the gelatine is dissolved.
After cooling, the gelatinous material is passed through muslin, and immersed for
6 hours in an alcoholic chlorophyll bath; it is taken out, washed for 6 hours with
water, and after the water has drained off, the material fused by heating and
filtered is applied as a coating to the glass plate for the blue negative.
The film for the red negative is prepared in a similar way except that no eosin
is used, and instead of the alcoholic chlorophyll bath, an alcoholic solution of aurine
of one per cent. strength is employed.
The film for the yellow negative is prepared similarly to that for the blue but
without subjecting it to treatment in any bath.
In taking the negatives, the light may be passed through coloured glass screens,
or the films prepared as above described for the negatives may be coloured, and in
that case the negatives may be taken either with or without the coloured screens.
The screens employed are, for the negative to reproduce blue, a bright yellow or
orange screen, for the red negative a green screen, and for the yellow negative a
light violet screen. When the films for the negatives are coloured, this is done as
follows:-
The negative for blue is immersed for about 10 minutes in a bath consisting of
1 gramme pouceau and 1 gramine bright or brilliant yellow with 1 litre distilled
water.
When the object has much pink colour, the negative should be dyed as for the
blue and a screen of bright yellow glass should also be used.
The negative for red is treated in a bath consisting of 1 litre of distilled water
with 1 gramme of bright yellow, or with gramme bright yellow and. grainme
Victoria blue.

page_text: The negative for yellow is treated in a bath consisting of 1 gramme Victoria blue
with 1 litre distilled water.
In these three cases instead of 1 litre of distilled water there may be employed
litre of water and litre of alcohol.
The exposure for producing the negatives necessarily depends on the light and
the character of the object photographed. Under ordinary circumstances, the
blue negative with the yellow screen or coloured film will, indoors, require about
10 seconds exposure, the red without screen or with coloured film will require
about 1 second and the yellow with violet screen or coloured film will require about
8 seconds.
Before developing the negatives, they should be washed in distilled water, and
if after developing any colour remains on the plates, it is removed by immersing
them for a few minutes in a bath of alcohol, or by merely washing with water in
the usual way.
The gelatine solutions to constitute the superposed films are prepared as follows.
For the yellow, 5 grammes of yellow chromium powder are dissolved in
250 grammes of water, for the blue, 1 gramme of Prussian blue is dissolved in the
like quantity of water, and for the red 1 gramme of carmine is dissolved in the
like quantity of water. Each of the solutions has added to it 35 grammes of
gelatine, heated till the gelatine is dissolved and filtered. Other pigments may be
employed, but I find those above mentioned very suitable.
'
For applying the gelatine solution, a piece of glass is placed in a dish filled with
warm water, a piece of white paper is laid on it, both are taken out of the water
and the paper after being pressed with a squeegee or roller to express surplus
water, is coated with the gelatine solution, and after the gelatine has set, is dried at
a temperature of about 30° C.
The papers thus coated with gelatine are then sensitised by immersion for a few
minutes in a bath of potassium bichromate of about 5 per cent. strength, and after
being dried in a dark room they are separated from the glass.
For printing on these papers the several negatives are placed on the sides of the
papers which are coated with gelatine and exposed in printing frames in the usual
way. When the printing is completed, each proof is placed with the gelatine
downwards on a waxed glass placed in cold water; the glass is taken out of the
water with the wet proof adhering to it, and the surplus moisture is squeezed out
of the paper.
The glass with the proof on it is then immersed in water heated to about 30° C.,
and after a few minutes the paper is peeled off from the gelatine which is left for a
few minutes until the image appears clear and transparent. Each of the gelatine
films on glass is then withdrawn from the hot water, washed well in cold water
and dried.
Having prepared the yellow, blue, and red coloured films on waxed glasses
printed photographically from their respective negatives, I effect their super-
position on a sheet of white paper by a process of manipulation which is as
follows.
I deal first with the yellow film and the paper on which the films are to be
superposed. I put this paper which has its one surface coated with gelatine into a
bath of cold water allowing it to remain there for about 5 minutes. 1 put the
glass carrying the yellow film in water heated to about 35° C. the yellow film
presented upwards; 1 take the gelatined paper from the cold water bath and lay
it with its gelatined side on the yellow film and after about two minutes of immer-
sion, I take the whole out together and leave them to dry. When dry I remove
the glass leaving the yellow film upon the paper. I then wipe the yellow film with
a cloth soaked in benzole so as to remove the wax coating which it had received
from the waxed glass on which it was originally formed.
For superposing the blue film on the yellow I first form a warm bath at
about 35° C. consisting of 100 grammes gelatine 100 grammes sugar dissolved in

page_text: two litres of distilled water and filtered, and in this bath I place the glass with
the blue film uppermost.
I soak the paper carrying the yellow film for about 2 minutes in a cold bath and
then place it face downwards on the blue; I immediately take the whole out of
the warm bath, and, looking through the glass adjust the blue film exactly in
register with the yellow and leave them to dry, after which I remove the glass,
and wipe the blue film with benzole to remove the wax.
For superposing the red film I first form a cold bath consisting of 150 grammes
gum arabic and 150 grammes sugar dissolved in 1 litre of distilled water and
filtered, and in this bath I place the glass with the red film uppermost.
On this I place the paper with the blue and yellow films downwards, and, after
about 10 minutes of immersion, I take out the whole; looking through the glass I
adjust the red film in exact register upon the others, and leave the whole to dry,
after which I remove the glass and polish the red film with a flannel. The paper
carrying the three superposed films can then be mounted as desired.
Although I have, by way of example, described the order of superposition as
being yellow, blue and red, this order may be varied.
It is to be understood that the operator has to take the usual precautions against
the action of light on the sensitised materials.
The process described is an example shewing how the invention can be carried
out practically, but the materials employed, their proportions, the times of exposure,
the number of negatives and films, their colours, and the details of manipulation
may be varied.
For instance, the coloured films, instead of being superposed on paper, may be
superposed on another suitable surface, and instead of employing gelatine for the
films, other known substances, such as albumen or collodion, capable of giving
transparent films, may be used, the manipulation being modified so as to suit the
particular substances employed.
Having thus particularly described and ascertained the nature of the said inven-
tion and in what manner the same is to be performed I would have it understood
that I make no general claim to the production or superposition of coloured
photographic films, but what I claim in respect of a process for photographing in
colours is :-
1. The process for preparing and taking the several negatives suitable for
printing photographically on differently coloured films, substantially as described.
2. The process for preparing the several differently coloured films and
photographically printing them from their respective negatives, substantially as
described.
3. The process of manipulation for superposing the photographically printed
films, substantially as described.
4. The complete process for photographing in colours consisting of the successive
steps of operation set forth in the preceding claims.
Dated this 10th day of June 1895.
ABEL & IMRAY,
Agents for the Applicant.