a Process therefor.
Year: 1888

page_text: a Process therefor.
I ERNST ZERR of Am Mittelthor Weissenburg, Alsatia in the Empire of Germany
Photographer do hereby declare the nature of this invention and in what manner the
same is to be performed to be particularly described and ascertained in and hy the
following statement :-
This invention relates to the manufacture of designs, pictures, medallions and the
like in relief, cameo or intaglio having the body and style of modelling or sculpture
and it consists more especially in certain improvements in the process of producing
designs etc. in relief by means of photography through the action of light upon
sensitized gelatine so as to adapt such process to the production of the reliefs above
described from drawings, portraits, photographs, from nature and the like.
A photographic negative is taken in the usual manner from the drawing or natural
object upon a gelatine or collodion sensitive plate, the same being however equal to
the power or contrast to the work to be performed therewith. If the drawings are
done in white upon a dark ground, a positive is made from the negative, if however
the drawings are in black on a light ground, the negative is used in the reproduction.
In portraits from nature it is usually necessary to take a positive from the negative
and to combine this positive with the negative and take another positive, therefrom,
so that the dress, hair etc. may have the same lighting as the face or flesh parts that
is to say, must show the same density as the flesh parts.
The plate of sensitive gelatine is made as follows. An emulsion is prepared of
gelatine and gum tragacanth in equal proportion (60 grammos emulsified in half a
litre of water) and poured upon a smooth glass plate to the thickness necessary up to
10 millimeters; after setting the mass is removed from the glass and placed face
downwards onto another glass or other suitable support so that the smooth surface
which was previously in contact with the glass is now uppermost. The mass is then
thoroughly dried. To sensitize this plate a solution is prepared containing :
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page_text: This solution is poured upon the plate (in a non actinic light) and the latter is
dried as quickly as possible in the dark room. This solution should dry with a matt
surface.
The matters used should be pure, and foreign matter should be carefully excluded
from the solution. The Gum Tragacanth should be carefully dissolved so that bubbles
are avoided, as the latter are difficult to remove. The duration of copying on a plate
so prepared varies according to the quality of the negative and actinic power of the
light it is usually from to 2 hours.
The developement of image is performed by immersing the exposed plate in clean
water until the upper layer retains the water and the gelatine layer begins to soften.
About ounce of glacial acetic acid is then added to the water which must well
cover the plato and the plate is left therein for about two to three hours. During
this time the upper Dextrine-gelatine layer is dissolved and the relief of the image is
gradually effected. After about three hours another ounce of glacial acetic acid is
added and so on again until the image is fully developed in relief. If the dextrine-
gelatine layer does not dissolve, the plate is practically useless as only very slight
relief can be obtained from such plate.
The heat of the bath should not exceed 15° Reaumur. When the relief is fully
developed the plate is washed in clean water until all the acid is removed and plaster
of Paris can be poured thereon to obtain a mould from which any number of metal,
porcelain, plaster or like casts may be obtained. Objects may be made by this process
standing in relief to a height of 5 to 6 mm.
Having now particularly.described and ascertained the nature of my said invention
and in what manner the same is to be performed I declare that what I claim is
In the manufacture of objects in relief
1. The process consisting in exposing photographically, a sensitive gelatine plate,
dissolving the soluble portions of said plate to obtain-an object in relief and making
a mould from said plate..
2. The preparation of a gelatine plate from an emulsion containing gelatine and
Gum Tragacanth, coating said plate with a solution of gelatine dextrine and bichromate
of potash exposing photographically said plate, dissolving the soluble portions thereof
with water and acetic acid substantially as and for the purpose set forth.
3. A sensitive plate having a coating of gelatine and gum Tragacanth and a second
coating of an emulsion of gelatine, dextrine and bichromate of potash or the like.
Dated this 16th day of November 1888.