An Improved Process for the Preparation of Moulds for Making Stereotypes, Reproducing Wood-cuts, and the like.
Year: 1890

page_text: Date of Application, 15th Feb.. 1890
Complete Specification Left, 17th Nov., 1890-Accepted, 17th Jan.. 1891
.
PROVISIONAL SPECIFICATION.
An Improved Process for the Preparation of Moulds for Making
Stereotypes, Reproducing Wood-cuts, and the like.
A communication from H. WEHMANN and PAUL MÜLLER, both of Bremen, in the
Empire of Germany, Engineers.
1, EDMUND EDWARDS, of the firm of Edwards and Co., Patent Agents and
Engineers, of 35, Southampton Buildings, Chancery Lane, in the County of
Middlesex, do hereby declare the nature of this invention to be as follows:-
In the methods hitherto ordinarily used for the preparation of moulds for stereo-
typing, either several layers of tissue paper have been used to which the necessary
stiffness was imparted by means of paste and the addition of thicker paper, the
surface of the tissue paper, being pressed or forced down by a brush into the depressions
or hollow parts of the type surface to be stereotyped; or a gypsum or plaster of paris
cast has been taken direct from the type or from the surface; of wood-cuts,, the
stereotype plate being afterwards obtained by casting it with type-metal in the
plaster mould so obtained, or by. electrotyping.
In, the first process the paper surface is easily torn or injured so that only a very
imperfect stereotype plate is obtained. Moreover, the edges of large printing
surfaces, and fine lines, are too sharply stamped, and the preparation of a plate fit for
printing is a troublesome and tedious, task for a skilful workman, and even in the most
favourable circumstances the fine lines and points are liable to take up more ink and
be, blacker in printing than the original.
Stereotyping by means of plaster is used in the preparation of castings from wood-
blocks but, this process is only rarely successful, for if the plaster sinks into the finest
depressions so as to form an accurate reproduction, the surface is never smooth but
takes up a great deal of ink so that the fine parts become blotched in printing.
The plaster moreover requires to be thoroughly dried, which occupies a long time
so that the stereotype casting is frequently defective on account of the hot metal
forming steam by contact with the imperfectly dried plaster.
Further, only one casting can be taken from each mould, the latter having to be
roken'in order to remove it from the metal.
The present invention has for its object a process, whereby the mould shall be an
accurately faithful reproduction of the original, whilst the mass being thoroughly
plastic can be when made immediately placed upon the surface to be moulded, and
is not liable to alter in drying. In order to put-the-invention in operation, sixty
parts of whitening, seventy parts of talc, forty parts of clay, and fifty parts of graphite,
in a dry and pulverized estate aro intimately mixed together sufficient water being
added to form a thick homogeneous paste..
With this paste are then incorporated twenty parts of glycerine, and two hundred
and forty parts by weight of thick boiled starch paste are finally added to the whole
mass.
The preparation of the mould is effected in the following manner.
+
Upon a damped sheet of thick unsized paper is first spread, a thin layer, of, the
composition just described, and upon, this, layer is, placed a damped, covering sheet
which is also coated with a thin layer of the composition a second, covering sheet
being laid upon the latter, and according to the nature of the surface to be
reproduced a small or large quantity, of the, composition is laid on, small, in, the, case
of printing type and large in the case of wood, blocks, etchings, and, generally, for the
finest work.
The original to be reproduced having been carefully, oiled the side of the mixture

page_text: last coated with the composition is laid upon it and a sheet of felt is placed upon the
back and the whole is subjected to a gradually increasing pressure in a suitable
press. In order that a uniform pressure may be exerted over the whole surface the
position of the mould should be occasionally altered.
To preserve from injury the fine parts of the mould the latter is surrounded with
pins of the same height as the printing surface.
When, after a short time, the mould 'has received a sufficiently deep impression,
a thick layer of paper is substituted for the felt, and the pressure is repeated with
greater force than before in order to obtain a very smooth surface.
The depressions which are visible in the back of the mould when the layer of
paper is removed are filled with pulp, whitening, or magnesia, which is retained by a
pasted sheet pressed upon it.
The mould is again covered with a layer of paper or felt and dried in a heating
press.
The mould when dried is then separated without trouble from the original.
The composition adheres firmly to the paper and prevents the latter from being
singed or burned by the fluid type metal.
The mould is hard but not brittle, being elastic, and separated so easily from the
metal that an almost unlimited number of castings can be obtained from the
same one.
For surfaces which it is not advisable to dry by heat, such for instance as wood-
blocks, the blocks of the composition to form the moulds are made and dried in
advance and kept in stock. Before they are made use of, the side which is coated.
with the composition is covered with a sheet of tissue paper, and the block is
placed between sheets of damped felt and left until it adheres to the finger when
brought into contact with it. The tissue paper is then taken away and the
superfluous moisture removed by a sheet of blotting paper, the surface being then
brushed over with graphite and placed upon the wood-block, which is also rubbed
with graphite or preferably oiled, and finally pressed in the manner already
described.
The pressed mould is not dried upon the wood-block but is withdrawn from the
latter and dried in a frame of suitable size.
As the wood-block in this way comes in contact with a mould only slightly
moistened it is not in any way injured.
Dated this 15th day of February 1890.
EDWARDS & CO.,
Agents for the Applicant.
COMPLETE SPECIFICATION.
An Improved Process for the Preparation of Moulds for Making
Stereotypes, Reproducing Wood-cuts, and the like.
A communication to me from H. WEHMANN, and PAUL MÜLLER, both of Bremen, in
the Empire of Germany, Engineers.
I, EDMUND EDWARDS, of the firm of Edwards and Co., Patent Agents and
Engineers, of 35 Southampton Buildings, Chancery Lane, in the County of
Middlesex, do hereby declare the nature of this invention, and in what manner the
same is to be perforined, to be particularly described and ascertained in and by the
following statement :-
In the methods hitherto ordinarily used for the preparation of moulds for stereo-
typing, either several layers of tissue paper have been used to which the necessary
stiffness was imparted by means of paste and the addition of thicker paper, the
surface of the tissue paper being pressed or forced down by a brush into the
depressions or hollow parts of the type surface to be stereotyped; or a gypsum or
plaster of paris cast has been taken direct from the type or from the surface of
wood-cuts, the stereotype plate being afterwards obtained by casting it with type-metal
in the plaster mould so obtained, or by electrotyping.

page_text: In the first process the paper surface is easily torn or injured so that only a very
imperfect stereotype plate is obtained.
Moreover, the edges of large printing surfaces, and fine lines, are too sharply
stamped, and the preparation of a plate fit for printing a troublesome and tedious
task for a skilful workman and even in the most favourable circumstances the fine
lines and points are liable to take up more ink and be blacker in printing than the
original.
Stereotyping by means of plaster is used in the preparation of castings from wood-
blocks but this process is only rarely successful, for if the plaster sinks into the finest
depressions so as to form an accurate reproduction, the surface is never smooth, but
takes up a great deal of ink so that the fine parts become blotched in printing.
The plaster morever requires to be thoroughly dried which occupies a long time so
that the stereotype casting is frequently defective on account of the hot metal forming
steam by contact with the imperfectly dried plaster.
.
Further only one casting can be taken from each mould, the latter having to be
broken in order to remove it from the metal. The present invention has for its
object a process whereby the mould shall be an accurately faithful reproduction of
the original, whilst the mass being thoroughly plastic can be when made immediately
placed upon the surface to be moulded, and is not liable to alter in drying.
In order to put the invention in operation, sixty parts of whitening, seventy parts
of talc, forty parts of clay, and fifty parts of graphite, in a dry and pulverized state
are intimately mixed together sufficient water being added to form a thick homogeneous
paste. With this paste are then incorporated twenty parts of glycerine and two
hundred and forty parts by weight of thick boiled starch paste, are finally added to
the whole mass.
The preparation of the mould is effected in the following manner.
Upon a damped sheet of thick unsized paper is first spread a thin layer of the
composition just described, and upon this layer is placed a damped covering sheet
which is also coated with a thin layer of the composition a second covering sheet
being laid upon the latter, and according to the nature of the surface to be reproduced
a small or large quantity of the composition is laid on, small in the case of printing
type and large in the case of wood blocks, etchings, and generally for the finest
work.
The original to be reproduced having been carefully oiled the side of the mixture
last coated with the composition is laid upon it and a sheet of felt is placed upon the
back and the whole is subjected to a gradually increasing pressure in a suitable press.
In order that a uniform pressure may be exerted over the whole surface the position
of the mould should be occasionally altered.
To preserve from injury the fine parts of the mould the latter is surrounded with
pins of the same height as the printing surface.
When after a short time, the mould has received a sufficiently deep impression,
a thick layer of paper is substituted for the felt, and the pressure is repeated with
greater force than before in order to obtain a very smooth surface.
The depressions which are visible in the back of the mould when the layer of paper
is removed are filled with pulp whitening, or magnesia, which is retained by a pasted
sheet pressed upon it. The mould is again covered with a layer of paper or felt and
dried in a heating press.
The mould when dried is then separated without trouble from the original.
The composition adheres firmly to the paper and prevents the latter from being
singed or burned by the fluid type metal.
The mould is hard but not brittle, being elastic and separated so easily from
the metal that an almost unlimited number of castings can be obtained from the
same one.
For surfaces which it is not advisable to dry by heat, such for instance as wood-
blocks, the blocks of the composition to form the moulds are made made and dried in
advance and kept in stock. Before they are made use of, the side which is coated
with the composition is covered with a sheet of tissue paper, and the block is placed

page_text: between sheets of damped felt and left until it adheres to the finger when brought
into contact with it. The tissue paper is then taken away and the superfluous
moisture removed by a sheet of blotting paper the surface being then brushed over
with graphite and placed upon the wood-block which is.also rubbed with graphite.or
preferably oiled, and finally pressed in the manner already described.
The pressed mould is not dried upon the wood-block but is withdrawn from the
latter and dried in a frame of suitable size.
As the wood-block in this way comes in contact with a mould only slightly moistened
it is not in any way injured.
Having now particularly described and ascertained the nature of the said inven-
tion and in what manner the same is to be performed, I declare that what I
claim is :-
The improved process for the preparation of moulds for stereotypes, wood-cuts or
the like, by the use of a composition of whitening, tale, clay, graphite and glycerine
for taking impressions which composition is laid upon the object requiring to be
moulded, being sufficiently plastic to produce a negative corresponding accurately
with the original, such negative being capable of being dried either upon the
original or after it has been removed therefrom, without the contouring edges or
outlines of the printing surface: being damaged, substantially as described.
Dated this 15th day of November 1890.
EDWARDS & Co.,
35, Southampton Buildings, Chancery Lane, Agents for the Applicant..