Improvements in the Production of Photographs in Natural Colours.
Year: 1895

page_text: Date of Application, 6th Apr., 1995
Complete Specification Left, 20th Dec., 1895-Accepted, 25th Jan., 1836
PROVISIONAL SPECIFICATION.
Improvements in the Production of Photographs in Natural
Colours.
1, GUSTAV SELLE of Brandenburg a/H. in the Empire of Germany, Doctor of
Philosophy, do hereby declare the nature of this invention to be as follows:-
This invention relates to the method of producing photographs in which objects
are represented in their natural colours, in which three negatives are produced
respectively from sensitive plates or the like exposed to the same image, one behind
a red light filter, another behind a green light filter and the third behind a dark
blue light filter; and the improvements are designed to simplify the production of
a combined positive from these three negatives.
The invention consists in producing separately three transparencies, one from each
of the three negatives, dyeing these positive transparencies each with a colour
complementary to the colour of the light filter used in the production of the
respective negative, and superposing the three dyed transparencies.
In carrying this process into effect the three negatives are produced by exposure
behind the respective light filters, and development in the usual way; the trans-
parencies are made as follows;-Taking a suitable support for instance a glass
plate, it is first coated round the edge only with a solution of gelatine, the surface
is then coated with collodion to form a thin film and the latter is again coated with
a light-sensitive chrom gelatine mixture. The plate is dried and may be exposed
under any one of the three negatives. Similar plates are made and. exposed
respectively under the other two negatives. The exposed plates are washed in
water and transferred cach to its respective dyeing bath. That exposed under
the "red" negative is placed in a bath of a colour complementary to red, for
instance methyl blue; that exposed under the "green" negative is placed in a
bath of a colour complementary to green, for instance fuchsin, and that exposed
under the "blue negative is treated to the complementary colour, for instance in
a bath of helianthin. The image is allowed to fully develop in the colour bath
whereupon the plate is removed, dried, and coated with collodion.
"
The three positives thus produced are assembled as follows;-the edges of the
rose-coloured positive produced under the " green" negative are cut through and
transfer paper is squeegeed to the back. The film is thus stripped from the glass...
and is laid upon the blue positive produced under the "red" negative which blue
positive has been previously conted with an adhesive material such as a solution of
gelatine. These are well pressed together and the transfer paper or temporary
support is removed. The yellow positive produced under the "blue" negative
(that is to say the negative resulting from exposure behind the blue light filter) is
then transferred in a similar manner onto the surface of the two other positives and
the combined positive thus produced may be attached to paper, opal glass or any
other permanent support.
Dated this 6th day of April 1895.
HERBERT HADDAN & Co.,
Agents to Applicant.

page_text: Improvements in the Production of Photographs in Natural
Colours.
I, GUSTAV SELLE of Brandenburg a/H. in the Empire of Germany, Doctor of
Philosophy, 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 present known processes for producing photographs in colors are broadly
of two kinds. In Lippmann's process the colored image is produced on one plate
only in interference colors whilst in the other method the colored photograph is
produced by superposing three single colored images produced with artificial colors
one upon the other.
.
In Lippmann's process the photography of living or moving objects seems
practically excluded on account of the necessarily long duration of exposure whilst
in the process described in the present. Specification which belongs to the second
category on account of the relatively short duration of exposure, also objects which
are quiet only for a short time can be photographed in colors.
In this present
method it is neither necessary. to make for each copy of the photograph a new
exposure as in Lippman's method nor is the production so difficult and circum-
stantial as for example in the. Vogel-Ulrich. method in which must be produced
colored plates from which printed impressions are made.
The present process. is divided essentially into two parts.
-1. The production of the negative.
2. The production by copying of the positive.
The production of the negative is made in the known manner by photographing
an object three times one after the other first behind a red; secondly behind a green,
and thirdly behind a dark blue, light filter.
The positive is produced by making three positives behind the corresponding
three. negatives each being then colored in the color complementary to the
light filter of its corresponding negative, and by putting these three positives one
over the other..
Such a complementary positive is made by covering with a thin collodion
skin serving as image carrier, a glass plate, which is surrounded with a rim
of: gelatine solution, and then pouring over the same plate a chromgelatine
emulsion;,
.
After having dried the plate so prepared it is exposed behind one of the
three negatives, for example the negative. I for red, then washed in cold water
and put into a color solution complementary to red, for example in a color bath of
methyl blue.
The plate remains in this bath until the blue image, is completely developed
whereupon it is taken out dried and covered with collodion:
In the same manner a second positive is produced by exposing a second
glass plate prepared in the same manner behind the negative 11 taken with
the green light filter. This is now developed in a color bath complementary
to.green for example in one of fuchsin and finally treated exactly as the blue-one.
In the same way is produced behind negative III the positive III which is
developed in a color bath complementary to blue, for example in one of helianthin.
When all three positives are produced they are superposed as follows :-- ;
The edges of, the rose image II are cut and a transfer paper is squeezed upon
it the thin collodion.skin is taken off with the paper and transferred upon positive I
(blue) which has been previously covered with gelatine as adhesive substance, the
2 images are put one upon the other pressed together and transfer paper is taken
off. In the same way the positive III (yellow) is transferred on the upper of the

page_text: other two and a positive in natural colors is thus produced which consists of collodion
or other thin skins and can be easily transferred to a permanent support of paper,
opal, glass, etc.
Having now particularly described and ascertained the nature of this said inven-
tion and in what manner the same is to be performed I declare that what I
claim is :-
1. A positive process for producing colored photographs comprising the employ-
ment of very thin but transportable collodion skins as image carriers which are
treated with chrom-gelatine emulsion whereupon after exposure behind corresponding
negatives the soluble salts are washed out in cold water and the image made
sensitive in this manner for color baths is developed in corresponding color baths.
2. In the method described in Claim 1 the production of photographs in natural
colors in the known three colors system by putting single colored collodion skins
produced according to Claim 1 one upon the other.
Dated this 20th day of December 1895.
HERBERT HADDAN & Co.,.
18, Buckingham Street, Strand, London, W.C.,
Agents to Applicant.