IMPROVEMENTS IN THE MANUFACTURE OF SENSITIVE PAPER AND BLOCKS OR TABLETS THEREOF, FOR PHOTOGRAPHIC PURPOSES
Year: 1881

page_text: PROVISIONAL SPECIFICATION left by William Thomas Morgan at the Office
of the Commissioners of Patents on the 13th December 1881.
WILLIAM THOMAS MORGAN, of Greenwich in the County of Kent. "IMPROVEMENTS
IN THE MANUFACTURE OF SENSITIVE PAPER AND BLOCKS OR TABLETS THEREOF,
FOR PHOTOGRAPHIC PURPOSES"
My Invention relates to the manufacture of sensitive paper and to blocks, pads,
or tablets of the same, for photographic purposes.
In carrying the said Invention into practice I take superfine paper (preferably
hand made) as free as possible from grain or texture marks and in order
to eliminate all traces of lime or impurities of any kind I pass it through a bath or
solution of strong acid, preferably sulphuric acid and water, and thoroughly rinse.
I 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, guin,
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 so essential to the
success of my process. This glazed or euanelled surface I obtain much in
the same manner as lithographers obtain their transfer impressions from
steel or copper engraved plates, that is to say, I 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 made 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 paraffin-wax, beeswax, or
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

page_text: 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 my Invention I
arrange the paper in the following manner that is to say; when the said paper bas
been prepared 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 metal sheets are then pressed into a
shell or matrix of any suitable curvature by a die or pressing device of corre-
sponding curvature which is subjectded 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 from 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.
·
My object in bending or curving these tilets 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.means-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 considrably 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 rushing over the same 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 discs my 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.