MENTS IN THE MANUFACTURE OF COLORED PHOTOGRAPHIC PICTURES.
Year: 1883

page_text: PROVISIONAL SPECIFICATION left by Josiah Adams the younger at the
Office of the Commissioners of Patents on the 8th May 1883.
JOSIAH ADAMS the younger of Liverpool in the county of Lancaster.
MENTS IN THE MANUFACTURE OF COLORED PHOTOGRAPHIC PICTURES.
"
IMPROVE-
In colouring photographs on glass, unless the color be in the glass itself, and the
photograph on the face, it has hitherto been considered impossible to get a uniform
tint to the back ground, as air gets between the white paper used as a backing
and the glass and causes deepened shades.
ensues.
If a glue or other adhesive be used, the paper is darkened and a greenish hue
Now as the photographs made on first mentioned plan, commonly known
as opal glass pictures or "opals," are very expensive, it has long been a great
desideratum to obtain pictures in which the whiteness of the opal glass is combined
with the cheapness of the transparent glass. In opal glass too, the paint being
between the eye and the photograph, the fine gradations of the photograph are
obscured thereby, and it is very difficult to paint an accurate likeness without a
sitter. In the transparent glass photographs the paint is behind the photograph,
and is seen through it, so does not obscure the photograph, and need not be so
accurate and artistically done.
My plan of operations is to place the photographic image on the back of the
plate, then paint its outer surface either after varnishing or otherwise. When the
paint is dry, coat the entire back with a mixture of oxide, of zinc gum and balsam,
or oxide of zinc and a drying oil. In place of oxide of zinc, the sulphide of zinc
may be used, if the colours used do not chemically decompose it, or other suitable
chemically neutral pigment could be used with either of these menstrua. While
the gum which can be gum copal, gum elemi, or other like transparent gum, is still
wet, a sheet of pure white cellulose paper is laid on, in such a manner as to avoid
the enclosing of air bubbles, and gently pressed against the photograph, so that the
menstruum in which the oxide of zinc or other pigment is suspended, shall
penetrate the pores of the paper, and be thus by capillary attraction withdrawn
from the surface of the photograph. The paper is allowed to dry on the plate, and
as evapouration goes on on the outer surface of the paper, still more of the
menstruum is withdrawn from the surface of the plate. The result is when the
[Di 71

page_text: whole has set, a clear, closely adhering coat envelops the surface of the plate, and
an effect almost if not quite equal to opal glass is obtained. Instead of pure
cellulose paper, other bibulous material could be substituted, but it must be
absorbent, not brittle, and absolutely neutral chemically. The bibulous matter in
some instances can be done away with altogether. Thus if a varnish menstruum
be used, it can be laid on thick, and before setting, the outer surfrce repeatedly but
gently washed with ether. The ether having a strong attraction for the menstruum,
rapidly draws it from the surface of the plate, leaving the pigment against the
latter. The result however is not as good, as it is liable to scratch or rub off, and
is but a poor and expensive substitute for the process already described.