IMPROVEMENTS IN THE MANUFACTURE OF SENSITIVE PAPER AND BLOCKS OR TABLETS THEREOF FOR PHOTOGRAPHIC PURPOSES WHICH INVENTION COMPRISES AN IMPROVED METHOD OF REPRODUCING PICTURES FROM SUCH PAPER ן
Year: 1882

page_text: PROVISIONAL SPECIFICATION left by William Thomas Morgan and Robert
Leamon Kidd at the Office of the Commissioners of Patents on the 13th June
1882.
WILLIAM THOMAS MORGAN, and ROBERT LEAMON KIDD, both of Greenwich in
the County of Kent "IMPROVEMENTS IN THE MANUFACTURE OF SENSITIVE PAPER
AND BLOCKS OR TABLETS THEREOF FOR PHOTOGRAPHIC PURPOSES WHICH INVENTION
COMPRISES AN IMPROVED METHOD OF REPRODUCING PICTURES FROM SUCH PAPER
ן,
Our invention relates to the manufacture of sensitive paper, and to blocks pads or
tablets of the same for photographic purposes, also to an improved method of
reproducing pictures taken upon such paper.
In carrying the said invention into practice We take superfine paper (preferably
hand made) as free as possible from grain or texture marks, and in order to eliminate
all traces of line or impurities of any kind we pass it through a bath or solution
of strong acid, preferably sulphuric acid, and water and thoroughly rinse; we then
coat the paper with an emulsion of ground asbestos, talc, chinese clay or other
substance of a similar nature in a solution of gelatine, starch, gum and alum,
when this is dry the paper is placed between highly polished steel or silvered plates
and subjected to very heavy pressure by being passed between rollers. This paper
is then again coated as before but with a stronger emulsion of the same materials
and when dry is ready for glazing or enamelling, that is to say, for receiving a
textureless glass-like surface, essential to the success of our invention. This glazed
or enamelled surface we obtain much in the same manner as lithographers obtain
their transfer impressions from steel or copper engraved plates, that is to say, wo
damp the prepared paper on the back and carefully lay it with the prepared
surface side downward on the polished metal or silvered plates, previously inade
warm, and this paper is again submitted to very heavy pressure.
The damp paper
will adhere to the metal plate, but on again warming the latter the paper may be
easily stripped off. The paper is then stretched over a block by means of a frame
similar to a linen-stretcher or by means of any other suitable apparatus; it is then
carefully polished by being rubbed over the surface with paraffine-wax, beeswax, or

page_text: any material of a similar nature dissolved in highly rectified spirits; it is then
coated by any of the well known methods, with a gelatine-bromide of silver
emulsion and when dry is ready for use.
This paper may be used for a variety of photographic purposes; pictures can be
produced upon it by means of photography which pictures may be afterwards
transferred to glass, canvas, opal, wood-blocks for engraving, or to any other
substance to which it is possible to attach paper. It will be found most useful for
decorative papers for windows, walls, panels and the like as any sized or shaped
picture can be made.
According to an important part of our invention we arrange the paper in
the following manner, that is to say, When the said paper has been pre-
pared in the manner above described it is cut into suitable sizes and any
number of these pieces are superposed one upon another, the prepared side being
upward and between each piece is placed a sheet of tin foil or similar material.
The papers so interleaved with metallic sheets are then pressed into a shell or
matrix of any suitable curvature by a die or pressing device of corresponding
curvature, which is subjected to heavy pressure and forces the paper and tin foil or
other metal into a curve. The whole is then bound around the edges as is done
with sketching or drawing blocks or pads; the tin foil assists the paper to retain
its curve and also protects the rear sheet froin light while the front one is being
exposed in the camera. The paper and metal may also be made into flat blocks,
exactly similar to the ordinary drawing blocks.
Our object in bending or curving these tablets, is that when they are placed in
the camera in position for exposure they have the same centre as the curved
surface of the lens and by this ineans perfect equality of illumination is obtained
over the whole surface. The lines are absolutely straight and the definition is
more clearly defined, and many more technical advantages are secured well known
to the profession. The use of stops or diaphragms (if these are not entirely dispensed
with) is considerably modified. The tablets are placed in the dark slide and exposed
in the same manner as an ordinary sensitive plate. After exposure, the exposed
sheet is detached from the block, and developed in the usual manner. The surface
to which the picture is to be transferred should be previously prepared by brushing
over the samo a solution of gelatine and alum, and allowed to dry. The picture,
while still wet, is pressed in contact with the surface to which it firmly adheres,
and when dry the paper may be stripped off leaving the picture.
The principle of curvature will also be found of great service in the process
of enlarging where it is desirable to obtain absolutely straight lines. The
picture having been produced on the paper can be transferred to a curved glass by
the process above described and the picture can be made to face either side by
attaching it to the concave or convex surface.
For magic lantern slides or dises our invention is very advantageous as pictures
taken on the curved paper are transferred to curved glass, and when thrown on
the screen will be found to cover the whole disc of light with perfect definition up
to the edges.
The
In transferring or reproducing the pictures taken upon such paper, although we
do not use glass in the production of the negative on the transfer paper we have
transferred it to glass in order to print therefrom in the usual manner.
negative has then been reversed and has again to be transferred for most ordinary
purposes of printing. We find however that the weight of the glass would be a
serious burden to travellers or those working away from home and its liability to
breakage is also much against its use. The double transfer necessary when glass
is used is also found to be tedious and delicate. We therefore, according to another
part of our invention, provide means whereby we entirely dispense with the use
of glass in any part of the production of the negative, by substituting for glass a
gelatino bichromatised transparent, insoluble, film which in addition to its advantage
over glass in respect to lightness, cost, and non-liability to breakage, obviates the
necessity for a double transfer as above explained. The thinness of the gelatine film

page_text: allows the negative to be printed from either side which is a very great advantage,
when required for the purposes of mechanical printing, photo-lithography, maps,
charts, and the like. We prefer to make the gelatino, bichromatised transparent
films above mentioned in the following manner, that is to say, we make a solution
consisting of 30 grains of best transparent gelatine, 5 grains of bichromate of
potash 30 minims of fresh Ox-gall, and 1 oz of water. We warm the whole of these
ingredients to a temperature of about 150° Fahrenheit and stir until the gelatine is
dissolved. We then take a piece of highly polished glass or other substance and
having previously converted it into a dish by pasting slips of paper around the
edges, we place it upon a levelling stand or perfectly level bench and pour in the
gelatine solution to any desired thickness. As soon as the solution is set the whole is
set up to dry either naturally or by artificial heat in a well lighted room. We then
wash out the bichromate salt and again allow the gelatinous composition to dry
after which it is stripped from the support and is ready for use in lieu of glass
plates.