A NEW AND IMPROVED PROCESS FOR OBTAINING COLORED PHOTOGRAPHIC PRINTS
Year: 1880

page_text: LETTERS PATENT to Francis Hughes Hallett, of Saint Alban's Place, Saint
James's, in the County of Middlesex, for an Invention of "A NEW AND
IMPROVED PROCESS FOR OBTAINING COLORED PHOTOGRAPHIC PRINTS."
(Void by reason of the Patentee having neglected to file a Specification in
pursuance of the conditions of the Letters Patent.)
PROVISIONAL SPECIFICATION left by the said Francis Hughes Hallett at
the Office of the Commissioners of Patents on the 18th August 1880.
FRANCIS HUGHES HALLETT, of Saint Alban's Place, Saint James's, in the
County of Middlesex. "A NEW AND IMPROVED PROCESS FOR OBTAINING
COLORED PHOTOGRAPHIC PRINTS."
This process consists in obtaining colour photographs by means of two impressions
from the negative, the first being a weak impressson in order to give the outline
for guiding the application of the colouring, and the second, after the colours have
been applied, being an impression of sufficient strength to give the clear drawing,
lights and shadows, and details of the picture.
In carrying out this process I first take the negative in the ordinary manner.
I then print on salted paper already sensitized a very light or faint proof of
each negative fixed and washed in the usual way.
When dry I immerse the print for two or three seconds only in pure alcohol,
then dry it again, and afterwards pass it through the rolling press.
The print is then coloured with an ordinary hair pencil in vegetable colours,
the various tints being laid on smoothly, flatly, and lightly, without any regard to
shading or softening off, but care being taken to have the tints brighter than they
are intended to be finally. The colours are applied with the following mixture
instead of with water :-
Albumen of egg
Distilled water
Pure glycerine
-
100 grammes.
25
"
-
25

page_text: It will be found that the print will colour more easily if it be slightly moistened
and placed on a piece of glass.
After the print has been coloured it is again passed through the rolling press.
When perfectly dry the coloured proof is immersed for a second time in pure
alcohol, and is then albumenized in a bath composed as follows:-Whites of egg
are beaten up, with two grammes of very pure sal ammoniac added for every 3
whites of egg, 20 per cent. of distilled water, and about 4 drops of acetic acid for
every 100 grammes of albumen. All is beaten up until the liquid attains a snowy
appearance, when it is left at least 8 days to stand. It is then decanted and
ready for the coloured print, which should be carefully passed over the bath and
allowed to remain floating about 60 seconds. The print is then dried by heat,
and finally passed through a sensitizing bath in order to be ready for the second
impression. This bath is composed as follows:-
Distilled water
Nitrate of silver
1000 grammes.
100 "
The proof is again dried, but this time not by heat, and a second impression
stronger than the first is then taken by laying the negative very accurately over
the first impression, so that all outlines, &c., rigidly correspond. This has the
effect of establishing the picture, throwing out high lights, &c. The proof is then
toned and fixed in the usual way, and can be afterwards enamelled.