Improvements in and relating to the Production of Coloured Photographs
Year: 1898

page_text: Date of Application, 9th Aug., 1898
Complete Specification Left, 8th May, 1899-Accepted, 17th June, 1899
PROVISIONAL SPECIFICATION.
Improvements in and relating to the Production of Coloured
Photographs,
I, CHARLES DICKER, of No. 80, Rue Joseph II, Brussels, in the Kingdom
of Belgium, Chemist, do hereby declare the nature of this invention to be as
follows:-
My invention relates to a process for the production of coloured photographs.
The methods hitherto known for preparing coloured photographs indirectly,
that is not in immediate connection with the photographic process itself, comply
very imperfectly with the requirements which in general apply to the details of
a photographic picture. The methods moreover in effect depend mostly upon the
skill of the person treating the picture, and consequently the pastels, water-
colours and oil-paintings so produced are essentially nothing but pictures in
which the more or less skilled hand of the artist re-produces the details of the
photographic picture in various degrees of perfection. It is true that by an
ingenious combination of covering and glazing colours an improvement has been
effected, inasmuch as the transparency of the latter enable the fine lights of the
photographic picture to be more clearly recognized; on the other hand, these
transparent colours have absolutely no effect on the half tones and deeper shades
of the picture, so that for the colouring for the latter only body colours can be
employed. Experiments have shewn that it is best for the elegance and good
effect of the coloured photograph if only such colours be taken which so to say
themselves penetrate in the separate pores of the picture, and possess both a great
intensity and also the quality of being easily absorbed. The aniline colours
possess these qualities but the application thereof is limited, apart from the
drawback that the colours also can only penetrate in the photograph to a certain
degree of saturation which does not suffice to colour the deepest shades. In the
case of photographs especially which are taken upon albumen or Aristo" paper
this especially applies whilst collodion or celloidine papers only possess the quality
of absorbing the colours in the moist condition. From this come very many
practical difficulties, for instance, the colours once laid on can no longer be
removed and the pictures if spoiled lose their value, moreover, the latter named
papers cannot be wetted as often as desired in order to retain their property of
absorption, but if they have once become dry they have lost their quality for
ever, consequently the colouring can only take place immediately after the removal
of the picture from the last water bath, and the work in view of the damp
condition of the paper and the tendency of the colours to run together makes a
good effect almost impossible. Added to this difficulty for treating photographs
in the unmounted condition with colour, there is another drawback, namely,
that the deeper shades cannot take up as much colour as will effectively suffice
for them so that the drawbacks of the present system are sufficiently obvious.
On this account the operation has been somewhat changed, and the photographs
<

page_text: have been treated with concentrated solutions of aniline at the back which colour
is intended to penetrate through the picture and appear on front; but this
method gives such a weak uncertain colouring that even when the photographs
are made transparent, no sufficient effect is obtained, moreover, the sensitiveness
of aniline colours to light render a treatment of this kind almost worthless.
The present invention has for its object a process which possesses great
simplicity, in comparison with the methods at present in use, and also shews such
extremely satisfactory results as to distance any other methods and be applicable
by anyone without knowledge of painting and without any particular skill.
This method is characterized by the treating of the finished mounted picture with
a slight covering of a gelatinous material, and then subjecting it at the requisite
parts to the action of an aniline colour. By this device is attained that the
gelatinous layer takes up the colour readily so that the pictures possess such a
brilliance and light that even the deepest shades appear to be thoroughly
saturated with colour and produce a very great effect. Of course in the carrying
out of this process, certain practical points must not be neglected, and even when
by the new process the colours are caused to penetrate into the deeper shades
of the photographs, it is desirable in taking these that only plates sensitive to
colour should be used, so that certain special colourers such as red, yellow,
green and blue which in the use of ordinary dry plates give false colour values
shall in correspondence with the transparent colours to be used possess a greater
or less covering in the negative and positive copies. It is well known that
certain colours such as red, yellow and green are re-produced in photographic
pictures even darker than they are seen with the eye, whereas even when the
ordinary orthochromatic dry plates which are supplied by the trade to some
extent remedy the above mentioned contrast, yet the negatives and copies thereof
produced by these plates with transparent colours do not give such clear and correct
coloured tones as is desirable for this purpose; even the interposition of yellow
glass when colour sensitive plates are being used does not create the requisite
balance, and experiments have shewn that the photographing takes place best
with the aid of red sensitized dry plates and a green light screen. In order
moreover to obtain a satisfactory result in the colouring of the photographic
representations, it is necessary that the same (three ground colours which are
hitherto made use of) shall be employed in the taking, partly as screens, partly
as sensitizers, so that when for instance for the colouring of the positive prints
red, blue and yellow are to be taken, also at the taking the bromide of silver
dry plate shall be rendered sensitive to colour by means of a red colouring
material, whilst the blue and yellow colour solution serves for covering gelatine
mirror plates which after drying are used together as a green light screen.
highest lights in the copies must be pure white. Morcover in copying certain
points of view must be kept in view and firstly care must be taken that the
prints receive a neutral tone as possible in the gold bath so that on the further
treatment thereof with the aniline colours no false colour effects are produced.
The gelatinous covering which in consequence of its porosity absorbs the colouring
matter, is preferably prepared by means of white gelatine dissolved in water,
because this article possesses especial advantage that it can easily be removed
again by warm water in case the colouring has over-passed the edges and
so on.
The
In order to protect the aniline colours applied against the influence of light,
the gelatine is added to the salts of chrome mordants and so on, obviously other
similar materials might be used instead of gelatine, such as collodion, glue,
albumen, isinglass, starch and so forth, in short any gelatinous substance. In
the colouring care should be taken that the absorption of the colouring matter
takes place at the same moment in which the brush comes in contact with the
gelatinous layer. As however it is not possible to outline the parts of the
pictures so quickly with the brush and the absorption does not take place equally
if the operation is slow, it is requisite in order to prevent an unequal absorption

page_text: from being visible to apply the colours considerably diluted and to repeat the
operation several times, which of course prolongs the process.
In order to remedy this drawback, those portions of the gelatinous layer which
are not to be coloured, can be covered at those parts which adjoin the portions
which are to be coloured with a spirit varnish insoluble in water. This is allowed
to dry and the surface to be coloured can then easily be treated with the colouring
matter. Those parts to which the spirit varnish has been applied will absorb
no colour and can afterwards be easily cleaned and the varnish removed by
means of cotton soaked in alcohol. By the consecutive application of the three
ground colours the required shade can easily be attained. After the colouring
is finished the picture is coated with collodion so that it is protected on the one
hand against outside influences and on the other hand the colouring is caused to
appear more bright. The process is of course applicable with any kind of photo-
graphs whether the same be upon paper, glass, porcelain, ivory, metal, mother-
of-pearl or other materials. In the case of production on a large scale the three
colours could be applied by means of printing or stencils.
of
1900
W. P. THOMPSON & Co.,
322, High Holborn, London, W.C.,
Patent Agents for the Applicant.
Improvements in and relating to the Production of Coloured
Photographs.
I, CHARLES DICKER, of No. 80, Rue Joseph II, Brussels, in the Kingdom
of Belgium, Chemist, 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 ;-
-
My invention relates to a process for the production of coloured photographs.
The methods hitherto known for preparing coloured photograplis indirectly
that is not in immediate connection with the photographic process itself, comply
very imperfectly with the requirements which in general apply to the details of
a photographic picture. The methods moreover in effect depend mostly upon the
skill of the person treating the picture, and consequently the pastels, water-
colours and oil-paintings so produced are essentially nothing but pictures in
which the more or less skilled hand of the artist reproduces the details of the
photographic picture in various degrees of perfection. It is true that by an
ingenious combination of covering and glazing colours an improvement has been
effected, inasmuch as the transparency of the latter enable the fine lights of the
photographic picture to be more clearly recognised; on the other hand, these
transparent colours have absolutely no effect on the half tones and deeper shades
of the picture, so that for the colouring for the latter only body colours can be
employed. Experiments have shewn that it is best for the elegance and good
effect of the coloured photograph, if only such colours be taken which so to say
themselves penetrate in the separate pores of the picture, and possess both a great
intensity and also the quality of being easily absorbed. The aniline colours
possess these qualities but the application thereof is limited, apart from the
drawback that the colours also can only penetrate in the photograph to a certain
degree of saturation which does not suffice to colour the deepest shades. In the
" Aristo" paper
case of photographs especially which are taken upon albumen or
this especially applies whilst collodion or celloidine papers only possess the quality

page_text: of absorbing the colours in the moist condition. From this come very many
practical difficulties, for instance, the colours once laid on can no longer be
removed and the pictures if spoiled lose their value, moreover, the latter named
papers cannot be wetted as often as desired in order to retain their property of
absorption, but if they have once become dry they have lost their quality for
ever, consequently the colouring can only take place immediately after the removal
of the picture from the last water bath, and the work in view of the damp
condition of the paper and the tendency of the colours to run together makes a
good effect almost impossible. Added to this difficulty for treating photographs
in the unmounted condition with colour, there is another drawback, namely,
that the deeper shades cannot take up as much colour as will effectively suffice
for them so that the drawbacks of the present system are sufficiently obvious.
On this account the operation has been somewhat changed, and the photographs¨
have been treated with concentrated solutions of aniline at the back which colour
is intended to penetrate through the picture and appear on front; but this
method gives such a weak uncertain colouring that even when the photographs
are made transparent, no sufficient effect is obtained, moreover, the sensitiveness
of aniline colours to light render a treatment of this kind almost worthless.
The present invention has for its object a process which possesses great
simplicity, in comparison with the methods at present in use, and also shews such
extremely satisfactory results as to distance any other methods and be applicable
by anyone without knowledge of painting and without any particular skill.
This method is characterized by the treating of the finished mounted picture with
a slight covering of a gelatinous material, and then subjecting it at the requisite
parts to the action of an aniline colour. By this device is attained that the
gelatinous layer takes up the colour readily so that the pictures possess such a
brilliance and light that even the deepest shades appear to be thoroughly
saturated with colour and produce a very great effect. Of course in the carrying
out of this process, certain practical points must not be neglected, and even when
by the new process the colours are caused to penetrate into the deeper shades
of the photographs, it is desirable in taking these that only plates sensitive to
colour should be used, so that certain special colourers such as red, yellow,
green and blue which in the use of ordinary dry plates give false colour values
shall in correspondence with the transparent colours to be used possess a greater
or less covering in the negative and positive copies. It is well known that
certain colours such as red, yellow and green are re-produced in photographic
pictures even darker than they are seen with the eye, whereas even when the
ordinary orthochromatic dry plates which are supplied by the trade to some
extent remedy the above mentioned contrast, yet the negatives and copies thereof
produced by these plates with transparent colours do not give such clear and correct
coloured tones as is desirable for this purpose; even the interposition of yellow
glass when colour sensitive plates are being used does not create the requisite
balance, and experiments have shewn that the photographing takes place best
with the aid of red sensitized dry plates and a green light screen. In order
moreover to obtain a satisfactory result in the colouring of the photographic
representations, it is necessary that the same (three ground colours which are
hitherto made use of) shall be employed in the taking, partly as screens, partly
as sensitizers, so that when for instance for the colouring of the positive prints
red, blue and yellow are to be taken, also at the taking the bromide of silver
dry plate shall be rendered sensitive to colour by means of a red colouring
material, whilst the blue and yellow colour solution serves for covering gelatine
mirror plates which after drying are used together as a green light screen.
highest lights in the copies must be pure white. Moreover in copying certain
points of view must be kept in view and firstly care must be taken that the
prints receive a neutral tone as possible in the gold bath so that on the further
treatment thereof with the aniline colours no false colour effects are produced.
The gelatinous covering which in consequence of its porosity absorbs the colouring
The

page_text: matter, is preferably prepared by means of white gelatine dissolved in water,
because this article possesses especial advantage that it can easily be removed
again by warm water in case the colouring has over-passed the edges and
so on.
In order to protect the aniline colours applied against the influence of light,
the gelatine is added to the salts of chrome mordants and so on, obviously other
similar materials might be used instead of gelatine, such as collodion, glue,
albumen, isinglass, starch and so forth, in short any gelatinous substance. In
the colouring care should be taken that the absorption of the colouring matter
takes place at the same moment in which the brush comes in contact with the
gelatinous layer. As however it is not possible to outline the parts of the
pictures so quickly with the brush and the absorption does not take place equally
if the operation is slow, it is requisite in order to prevent an unequal absorption
from being visible to apply the colours considerably diluted and to repeat the
operation several times, which of course prolongs the process.
In order to remedy this drawback, those portions of the gelatinous layer which
are not to be coloured, can be covered at those parts which adjoin the portions
which are to be coloured with a spirit varnish insoluble in water. This is allowed
to dry and the surface to be coloured can then easily be treated with the colouring
matter. Those parts to which the spirit varnish has been applied will absorb
no colour and can afterwards be easily cleaned and the varnish removed by
means of cotton soaked in alcohol. By the consecutive application of the three
ground colours the required shade can easily be attained. After the colouring
is finished the picture is coated with collodion so that it is protected on the one
hand against outside influences and on the other hand the colouring is caused to
appear more bright. The process is of course applicable with any kind of photo-
graphs whether the same be upon paper, glass, porcelain, ivory, metal, mother-
of-pearl or other materials. In the case of production on a large scale the three
colours could be applied by means of printing or stencils.
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:
1. The method of producing coloured photographs, such method consisting
first in covering the photograph with a gelatinous compound, and second in apply-
ing the colours to the surface of said compound, substantially as described.
2. The method of producing coloured photographs, the method consisting first
in applying to the photograph a coating of gelatinous compound, second in covering
said compound, at the parts not to be painted, with a varnish insoluble in water.
third in applying the colours to the gelatinous compound, and fourth in removing
the varnish by the application of a spirit in which the varnish is soluble, sub-
stantially as described.
3. As a new article of manufacture, a photograph having colours laid thereon,
and a coating of collodion spread over said colours, substantially as described.
4. The method of producing coloured photographs, the method consisting first
in applying to the photograph a gelatinous compound, second in applying to
said compound at the points not to be coloured a varnish insoluble in water, and
third in applying colours to said gelatinous compound, substantially as described.
W. P. THOMPSON & Co.,
Of London, Liverpool, Manchester and Birmingham.