A NEW METHOD OF PRINTING FROM PLATES OF GELATINE OR EQUIVALENT MATERIAL
Year: 1875

page_text: PROVISIONAL SPECIFICATION left by Ernest Edwards at the Office of
the Commissioners of Patents, with his Petition, on the 15th
April 1875
I, ERNEST EDWARDS, of No 8, Hancock Street, in the City of Boston,
in the United States of America, Heliotyper, do hereby declare the
nature of the said Invention for "A NEW METHOD OF PRINTING FROM PLATES
OF GELATINE OR EQUIVALENT MATERIAL," to be as follows:-
The object of my Invention is to produce impressions from gelatine
or analogous substances in any of the colors known as dyes as dis-
tinguished from printing inks.
My Invention is based on the well known fact that gelatine, gum,
albumen, fibrine, and analogous substances are ordinarily absorbent of
water, but may be rendered non-absorbent by certain well known means,
such as the formation of chromic acid by the action of light upon
bichromatized gelatine or by the application of chrome alum or tannin.
In previous applications of this principle, those portions of the
gelatine which by such means are rendered non-absorbent have been
"

page_text: used by various devices to produce the print or picture. I have dis-
covered however that those portions of the gelatine which after such
treatment remain still absorbent may also be used to produce a print or
picture, by causing such remaining absorbent parts to absorb or take up
a quantity of water containing in solution any convenient color or dye.
It will be readily understood that by placing paper or other suitable
material on such a surface and applying sufficient pressure, the paper or
other material will receive the color from the gelatine plate in just such
proportion as the gelatino has been allowed to remain absorbent.
My Invention consists in producing impressions with colors known as
dyes, as distinguished from printing inks from plates consisting of
gelatine, gum, albumen, fibrine, or analogous substances, which are
absorbent of water, the parts which are not required to print having
been rendered non-absorbent of water, or otherwiso suitably prevented
from printing
I will describe the mode by which I have successfully prepared and
printed from such plates according to my said Invention. Upon a
suitable surface of metal, wood, stone, glass, or other suitable material,
I place a layer of gelatine, gum, albumen, fibrine, or analogous
substance, on which an image has been or is to be produced by
rendering such portions as are not required to print non-absorbent of
water by any of the well known means.
In preparing the gelatine or equivalent plate I have found the
following to be a convenient formula -I take of gelatine 1 oz.; water
6 oz., bichromate 30 grs. ; I disolve the gelatine and bichromate in the
water heated for the purpose and spread the mixture upon a surface of
slate When dry the plate is to be exposed to light under a photo-
graphic positive (as distinguished from a negative) After an exposure
sufficient to render non-absorbent those parts not to be printed the plate
is washed with water till all bichromate has disappeared, it is diied and
is then ready for use. In place of a photographic positive a design or
tracing may be used, or the bichromate may be omitted and a design
drawn directly on the gelantine (or transferred thereto) with chrome
alum. Or a design may be drawn on or transferred to the gelatine in
an opaque or waterproof varnish, the portions of gelatine not covered
with the varnish being then rendered non-absorbent. Or a stencil plate
or mask may be used so as to mechanically prevent the portions of the

page_text: gelatine covered by it from imparting any of the solution in those parts.
to the paper on which the impression is to be made.
Impressions may be taken from the plate prepared as above described
in the following manner -The surface of the prepared gelatine or
equivalent plate is to be wetted or dampened with a solution in water
of the desired color and the surplus moisture is to be removed by any
convenient means; the paper or other material on which the image is to
be printed is then to be pressed upon the surface of the plate, so as to
receive a portion of the color. As the colors to be used in this kind of
printing and known as dyes are soluble in water, and as these colors aro
to be applied to the surface of the plate in solution they will not be
absorbed by the parts of the plate which have been rendered non-
absorbent of water, but in the other portions they will be absorbed just
in proportion as the absorbent property has been modified by the
treatment which the gelatine has received When the colors used arc
dyes which require mordants to strengthen the color, the dyes ru
mordants may be applied in any convenient manner or order. Care
must be taken however to use, only such dycs or mordants as do not
iniuriously affect the colative plate

page_text: albumen, and other analogous bodies, which are absorbent of water, with
soluble colors known as dyes, in contradistinction to those known as
printing inks, the parts not required to produce an impression having
been previously 'rendered non-absorbent of water and incapable of
printing either by exposure to light, the application of a coagulating
substance, an opaque varnish or mat, or other suitable means sub-
stantially as specified and for the purpose set forth.