Improved Processes for the Production of Plates and Cylinders for Printing and Embossing.
Year: 1889

page_text: Date. of Application, 9th Jan., 1889
Complete Specification Left, 27th June, 1889-Accepted, 3rd Aug., 1889.
PROVISIONAL SPECIFICATION.
Improved Processes for the Production of Plates and Cylinders for
Printing and Embossing..
I ALFRED MICHAUD of 20 Boulevard Jourdan, Paris, France, Chemist; do hereby
declare the nature of this invention to be as follows:-
My invention relates to improved processes for the production of plates and cylinders
for printing on paper and fabrics, for ceramic decoration as well as for obtaining
relief impressions or embossing flexible materials such as paper, leather, fabrics,, &c..
In the production of flat or cylindrical surfaces, some of the means employed aro
derived from the known properties possessed by bichromated gelatine,, and I have
been enabled to obtain moulded surfaces which may either be utilized directly, or serve
for the production of engraved metallic surfaces.
Such methods have heretofore been proposed, but they have failed to produce the
desired results' owing to the imperfect conditions under which they have been put into
practice. Hence they have been almost entirely abandoned.
This invention is based on
1st. The employment of non-extensible and permeable surfaces, such as muslin
rendered electrically conductive and converted into an extremely, fine wire gauze.
This inextensible tissue forms the foundation for my compound gelatinous surfaces
which are indispensable when it is necessary to preserve tlie exact dimensions and
perfect register of the parts.
2nd. Development after exposure upon thin flexible copper or upon bristol board
previously impregnated and coated with bichromated gelatine and exposed when the
films of gelatine to be exposed under negatives are thick especially when it is
necessary to proceed by the wet way for obtaining plaster casts for use as moulds.
These flexible surfaces are especially valuable as they admit of obtaining several
moulds in succession from the same print, which cannot be done with prints
developed on rigid surfaces, owing either to the breakage of the plaster on detaching
it from the print, or to the latter becoming damaged at the first moulding.
3rd. The prints are allowed to dry when completely developed and then again
immersed in water in order to swell them sufficiently for obtaining a perfect mould
therefrom. By this method a mould is obtained in which the finest details are
reproduced, instead of the imperfect mould which the same print would furnish were
it used immediately after development.
The gelatine print having thus been obtained, I may proceed either by the dry or
wet method to obtain an engraved surface therefrom.
Dry moulding by pressure. For this purpose I may either employ an easily. fusible
alloy composed of
These metals should be pure and the alloy should be remelted several times.
The impressed plate or mould composed of this alloy should be immediately placed
in an alkaline silver galvanic bath before immersing it in the ordinary copper bath as
will be hereinafter described.
Or in place of this alloy I may employ a film which also forms very perfect moulds
made of gutta percha dissolved in chloroform to which a solution of caoutchouc is
added in sufficient proportion to give elasticity combined with firmness. The gutta
percha film is silvered or blackleaded before and after moulding in the cold.

page_text: Wet moulding with plaster. When the gelatine print after being swelled in water
has attained the desired condition it is covered with carefully guaged plaster which is
allowed to set, after which the print is easily detached. Care is taken to make the
plaster cast of considerable thickness as immediately it has acquired the necessary
hardness, a counterpart is obtained therefrom by pressure by means of a specially
prepared paste composed of gutta percha and wax melted together and to which
black lead is then added, care being taken to prevent the formation of air bubbles
in the mass.
After mixture the mass is to be spread evenly by mechanical means
upon a fabric. This coated fabric is silvered or blackleaded before and after pressure,
as when operating with the gutta percha film.
It will be understood that large engraved surfaces may be produced by successive
mouldings of repeats of the same subject and also that the several parts of the same
subject may be separately produced so as when combined together to compose
but one engraved surface.
The moulds thus obtained are then subjected to the following manipulations when it
is desired to convert them into engraved cylinders.
If a fusible metal mould be employed it is laid face outwards in a semi-cylindrical
cavity and pressure applied to cause it to acquire the desired curvature. In this
manner it may be brought to the form of a complete cylinder which is then
treated in the manner hereinafter described for flexible moulds (gutta percha film and
counterpart).
The edges of the surface which are to be afterwards brought together are so cut as
to have a margin left uncovered of from 2 to 3 millimetres in breadth beyond the
dimensions of the cylinder.
The mould is now stretched upon a frame and the metallization carefully effected by
immersion in an acid galvanic bath and when the metallic deposit has attained a
thickness of from about to of a millimetre, the mould thus coppered is wound upon
a wood cylinder of suitable dimensions which has been previously saturated with
melted wax. The two margins are then applied one on the other and over them is
placed a flat strip of copper waxed and blackleaded, so as to bind them in place,
the whole being secured upon the cylinder by means of a cord wound spirally upon
it from end to end.
The cylinder is then again immersed in the galvanic bath and removed from time
to time for the purpose of shifting the position of the cord, which is removed entirely
immediately the binding strip has become soldered by the galvanic action. When
the galvanic cavity has acquired sufficient thickness to permit it to be handled
without risk, it is removed from the bath and detached from the mould after being
cut along the edges of the binding strip of copper. The cut edges are trued up with
a file in order that they may be brought accurately together edge to edge, after
which the shell, with the engraved side inwards, is applied upon a metal cylinder
truly turned and covered with velvet and held in place by means of fine but strong
binding thread upon which is wound a sheet of gutta perclia which is rendered sticky
and adhesive by the application of heat on its inner surface at intervals.
operation is continued until the sheet is coiled twice round the cylinder, into which
a little hot water has been introduced, and the whole is then tightly bound by
means of a cord and allowed to remain for some hours. The inner cylinder is
then removed leaving the galvanic shell intact, protected on the outside and held
rigid by the hard gutta percha covering. The interior engraved surface is then
cleaned and afterwards immersed in a galvanic bath for producing an engraved
cylinder threfrom by electrotypy.
The
In order to obtain a good and regular deposit of the copper it is important that
the porous vase, if such be used, or the copper pole from which the roller is to be
formed by the passage of the current from a machine, be placed concentrically with
the axis of the hollow cylinder.
Remarks (1) If after having obtained the metal moulds by pressure as before
described, it be found that their surfaces are not perfectly true, they are first planed
at the back to a thickness of from 2 to 3 millimetres and then curved as described,

page_text: after which they are introduced into a truly bored hollow cast iron cylinder .and
within them is placed two semi-cylindrical cores of wood covered with felt between
which a wedge is driven whereby the engraved surface of the mould is pressed
against the sides of the cylinder and caused to assume a perfectly cylindrical form.
By this method, and with the aid of fusible metal, it is possible to convert any
existing flat engraved surface into a true cylinder whatever may be the irregularities
of its surface. The cylinder on being removed from the bath should be first stripped
of the gutta percha envelope and then of the shell bearing the relief surface.
(2) In order to separate this shell of varying thickness from the intaglio surface
obtained therefrom by electrotypy so that it may be used for the production of other:
engraved cylinders I employ a very simple means whereby the relief surface may.bo
presorved absolutely intact, consisting of a suitable small flat metal bar thinned.
along one side and rounded at one end, to which is attached a strip of fabric of
sufficient length to encircle the cylinder. By introducing the metal bar at the point.
of junction of the two edges of the relief shell and drawing it through while the.
double cylindrical ring is held stationary, the relief shell may be detached from the
electrotype without injury, thus avoiding the necessity of preparing fresh reliefs.
From an engraved cylinder others may be produced by cutting at a suitable part of
the surface a fine straight groove of a sufficient depth and insert in it a knife edged.
copper strip let into a hard wood back of conical section, so as to project for a
fraction of a millimetre only, the copper strip being greased before it is applied. When
a sufficiently thick deposit has been obtained, the copper strip is removed from the
groove in which it was inserted and a fresh incision is made with the aid of a
graver so as to sever the metal which has been deposited, after which the separation
of the relief counterpart from the engraved cylinder is effected as above explained.
The cylinder after leaving the electrotyping bath and stripped of its gutta percha
envelope and relief shell, is in the form of an open-ended tube rough on the inside
and hearing on its surface the engraving to be obtained. In order to render it suit-.
able for printing from, the engraved surface is first rubbed over with a mixture of size
and whiting and when dry the cylinder thus protected is introduced into a cast-iron
cylinder truly bored internally so that the former may be easily entered without injury.
It is then heated over a furnace and the interior of the electrotype cylinder is tinned
when the proper temperature is obtained. A second hollow cast-iron cylinder of
smaller dimensions than the copper cylinder and tinned on its exterior surface
(which like the interior is left rough, the ends only being turned so as to enable it to
be fitted on to a gas or steam jet pipe which subsequently forms a journal for the
printing cylinder) is then introduced concentrically within the copper cylinder still
enclosed in its cast iron casing, the parts being held in position by turned metal end
rings through which project the ends of the small cast iron cylinder. An alloy of lead
and antimony is then run in through a hole in the upper ring so as to fill the annular
space between the copper cylinder and the interior cast iron cylinder. The union of
the two is effected. The casings are then removed from the finished cylinder, and the
ends of the cylinder are then turned in the lathe.
The following are details which may be added to the foregoing description:-
(1) When metallic relief surfaces are to be directly produced from the intaglio
plaster moulds before referred to, the latter after being dried are dipped into a
heated bath of melted wax so as to be impregnated in an upward direction. They
are then removed from the bath, cooled, and immersed in water until saturated, after
which they are drained and the surface washed by pouring on it strong alcohol in
order to remove the last traces of air which might remain in the fine parts of the
design. They are then immediately immersed in a silver reducing bath in which the
metallization is effected in a uniform and perfect manner, the electrotyping being
effected on leaving this bath, by immersing in the ordinary copper bath.
(2) When it is desired to reproduce a previously existing plate from embossed
counterparts in leather, paper, or other fabric, etc., one similar in every respect to the
first may be obtained without recourse to the original drawing, by proceeding in the
following manner :-The embossed fabric, leather, or paper, is impregnated with an

page_text: alcoholic solution of gum-lac and allowed to dry thoroughly; it is then wetted by
dipping in water and gauged plaster is then run on its wetted surface and spread
evenly thereon.
When set the plaster cast is detached from the original and the
subsequent.operations are then the same as before.
(3rd) The processes in use for backing up small electrotypes may be employed, but
in certain cases where for example the plate is required to be heated while in use,
unequal expansion takes place and consequent distortion.
The
The following method is therefore adopted for plates of all dimensions.
electro is tinned after protecting the engraved side as usual, the tin filling the cavities
to a level only with the projecting parts. After cooling, the face-of the engraving
is covered with a protective sheet of gutta-percha, after which a rough file is passed
over it to lay bare the tinning and protecting portions of the copper. It is then
dipped in an alkaline bath to ensure the necessary adhesion and afterwards in the
ordinary electrotyping bath where it is backed up to the desired thickness, care being
taken to ensure an even deposit in order to avoid the labor of subsequently
levelling.
The same method is adopted for large sized plates, except that an apparatus is used
for preventing distortion during the operation. This apparatus, which resembles a
field harrow in appearance, is made of rectangular form and composed of a series of
parallel iron bars connected by cross bars, and provided with movable teeth or pins
placed about 4 inches apart which are adjusted at the desired height by means of set
screws. It is supported at the four corners upon fixed legs.
When it is desired to plate and level the back of a large engraved plate, it is laid
with its protected face downwards upon a cast iron plate of the same dimensions or
rather larger, and heated by means of gas jets. The apparatus above described is then
applied over it with the pins at its four corners resting upon the cast iron plate, and
all the pins are then adjusted so that their blunt points shall bear freely upon any part
of the back of the plate and fix them in that position. The cast iron plate is then
heated and when the copper is at the proper temperature, the tinning is proceeded
with 'to level the whole surface. If the pressure of the apparatus is insufficient to
prevent the plate getting out of shape, it may be increased by temporarily placing
weights upon it.
The small cavities left after cooling at the points where the pins have rested are filled
with the same alloy 'by means of a soldering iron. The entire surface is next filed
and the engraved side protected in readiness for immersing the plate in the electro-
typing bath.
COMPLETE SPECIFICATION.
Improved Processes for the Production of Plates and Cylinders for
Printing and Embossing.
1, ALFRED MICHAUD, of 20, Boulevard Jourdan, Paris, France, Chemist, 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 by the following
statement:-
My invention relates to improved processes for the production of plates and
cylinders for printing on paper and fabrics.
Such plates or cylinders will be especially useful for the purposes of ceramic
decoration as well as for obtaining relief impressions or for embossing flexible
materials such as paper, leather, fabrics, etc. Some of the means employed are
derived from the 'known properties possessed by bichromated gelatine, and I have
been enabled to obtain moulded surfaces which may either be utilized directly or
serve for the production of so-called " engraved" metallic surfaces for printing from.

page_text: Such methods have heretofore been proposed, but they have failed to produce the
desired results owing to the imperfect conditions under which they have been put
into practice. Hence, they have been almost entirely abandoned.
This Invention is based on,
1st. The employment of non-extensible and permeable surfaces, such as muslin
which has been rendered electrically conductive and converted into an extremely fine
wire gauze.
This inextensible tissue forms the foundation for my compound
gelatinous surfaces which are particularly necessary when it is required to preserve the
exact dimensions and perfect register of the parts.
2nd. Development after exposure upon thin flexible copper or upon cardboard
previously impregnated and coated with bichromated gelatine and exposed.
When
the films of gelatine to be exposed under negatives are thick, especially when it is
necessary to proceed by the wet way for obtaining plaster casts for use as moulds or
matrixes, these flexible surfaces are especially valuable, as they admit of obtaining
several moulds in succession from the same print which cannot be done with prints
developed on rigid surfaces, owing either to the breakage of the plaster on detaching
it from the print or to the latter becoming damaged at the first moulding.
3rd. Drying the prints when completely developed and then again immersing them
in water in order to swell them sufficiently for obtaining a perfect mould therefrom.
By this method a mould is obtained in which the finest details are reproduced, instead
of the imperfect mould which the same print would furnish were it used immediately
after development.
The gelatine print having thus been obtained, I may proceed either by the
dry or wet method to obtain therefrom a so-called "engraved" surface for printing
from.
Dry moulding by pressure. For this purpose I may employ an easily fusible alloy
These metals should be pure and the alloy should be remelted several times. The
impressed plate or mould, composed of this alloy, should be immediately placed in an
alkaline silver bath before immersing it in the ordinary copper bath, as will be herein-
after described.
Or, in place of this alloy, I may employ a film, which also forms very perfect moulds,
made of gutta percha dissolved in chloroform to which a solution of caoutchouc is
added in sufficient proportion to give elasticity combined with firmness. The gutta
percha film is silvered or blackleaded before and after being impressed or moulded in
the cold.
Wet moulding with plaster. When the gelatine print, after being swelled in water,
has attained the desired condition it is covered with carefully gauged plaster which is
allowed to set after which the print is easily detached. Care is taken to make the
plaster cast of considerable thickness as, immediately it has acquired the necessary
hardness, a counterpart is obtained therefrom by pressure by means of a specially
prepared paste composed of gutta percha and wax melted together and to which
black lead is then added, care being taken to prevent the formation of air bubbles in
the mass.
After mixture, the mass is to be spread evenly while hot by mechanical
means upon a fabric. This coated fabric is silvered or blackleaded before and after
being impressed, as when operating with the gutta percha film.
It will be understood that, for large surfaces, successive impressions or mouldings
may be made of repeats of the same subject, and also that the several parts of the
same subject may be separately produced so as, when combined together, to compose a
whole.

page_text: "
The moulds or matrixes thus obtained aro then subjected to the following
manipulations when it is desired to produce engraved cylinders for printing,
The mould, if of fusible alloy, is laid face outwards in a semi-cylindrical cavity and
pressure applied to bring it to the desired curvature. In this manner it may be
brought to the form of a complete cylinder which is then treated in the manner
hereinafter described for flexible moulds, formed of gutta percha film and gutta percha
coated fabric, next described.
The edges of these flexible moulds, which are to be afterwards brought together,
should have a margin left uncovered of from two to three millimetres in breadth
beyond the dimensions of the cylinder to be formed. The mould is stretched upon a
frame and the metallization carefully effected by immersion in an acid galvanic bath
and when the metallic deposit has attained a thickness of from about to of a
millimetre the mould thus coppered is wound upon a wood cylinder of suitable
dimensions which has been previously saturated with melted wax. The two margins
are then brought together and over the join is placed a flat strip of copper waxed and
blackleaded so as to bind them in place, the whole being secured upon the cylinder
by means of a cord wound spirally upon it from end to end. The cylinder is then
again immersed in the galvanic bath and removed from time to time for the purpose
of shifting the position of the cord which is removed entirely, immediately the joint
strip has become soldered by the galvanic action. When the galvanic coating has
acquired sufficient thickness, it is detached from the mould after being cut along the
edges of the joint strip of copper. The cut edges are trued up in order that they
may be brought accurately together edge to edge, after which the shell, with the
engraved side inwards is applied upon a truly turned metal cylinder covered with
velvet and is held in place thereon by means of fine, but strong, binding thread.
Upon it is wound a sheet of gutta percha, rendered adhesive on its inner surface by
the application of heat. The sheet is coiled twice round the cylinder, into which a
little hot water has been introduced and the whole is then tightly bound by means of
a cord and allowed to remain for some hours. The inner cylinder is then removed
leaving the galvanic shell intact, protected on the outside and held rigid by the hard
gutta percha casing. The interior "engraved" surface is then cleaned and afterwards
immersed in a galvanic bath for producing therefrom by electrotypy, a (seamless
engraved" cylinder for printing from. In order to obtain a good and regular
deposit of the copper, it is important that the porous vase, if such be used, or the
copper pole be placed concentrically with the axis of the hollow cylinder.
"
Remarks. (1) If, after having obtained the metal moulds by pressure, as before
described, it be found that their surfaces are not perfectly true, they are first planed at
the back to a thickness of from two to three millimetres and then curved, as described,
after which they are introduced into a truly bored hollow cast iron cylinder and
within them are placed two semi-cylindrical cores of wood covered with felt between
which a wedge is driven whereby the engraved " surface of the mould is pressed
against the sides of the cylinder and caused to assume a perfectly cylindrical form.
By this method, and with the aid of fusible metal, it is possible to convert any
existing flat "
engraved surface into a true cylinder whatever may be the
irregularities of its surface. The cylinder, on being removed from the bath, should be
first stripped of the gutta percha envelope and then of the shell bearing the relief
surface.
(2) In order to separate this shell from the intaglio surface obtained therefrom by
electrotypy, so that it may be used again for the production of other "engraved
cylinders, I employ a very simple means whereby the relief surface may be preserved
absolutely intact, consisting of a small flat metal bar thinned along one side and
rounded at one end, to which is attached a strip of fabric of sufficient length to
encircle the cylinder. By introducing the metal bar at the point of junction of the
two edges of the relief shell and drawing it through while the double cylindrical ring
is.held stationary, the relief shell may be detached from the electrotype without injury,
thus avoiding the necessity of preparing fresh reliefs.

page_text: From an "engraved " cylinder others may be produced by cutting at a suitable
part of the surface, a fine straight groove of a sufficient depth and inserting in it a
knife-edged copper strip let into a hard wood back of conical section so as to project
for a fraction of a millimetre only, the copper strip being greased before it is applied.
When a sufficiently thick deposit has been obtained, the copper strip is removed from
the groove in which it was inserted during the electrotyping operation and a fresh
incision is made by a graver along the same groove so as to sever the metal which
has been deposited after which the separation of the relief counterpart from the
"engraved cylinder is effected as above explained.
The cylinder, after leaving the electrotyping bath and stripped of its gutta percha
envelope and relief shell, is in the form of an open ended tube rough on the inside
and bearing on its surface the "engraving" to be obtained. In order to render it
suitable for printing from, the "engraved" surface is first rubbed over with a mixture of
size and whiting and, when dry, the cylinder thus protected is introduced into a cast-iron
cylinder truly bored internally so that the former may be easily entered without
injury. It is then heated over a furnace and the interior of the electrotype cylinder
is tinned when the proper temperature. is obtained. A second hollow cast-iron
cylinder of smaller dimensions than the copper cylinder and tinned on its exterior
surface (which, like the interior, is left rough, the ends only being turned, so as to
enable it to be fitted on to a gas or steam jet pipe which subsequently forms a journal
for the printing cylinder) is then introduced concentrically within the copper cylinder,
still enclosed in its cast iron casing; the parts being held in position by turned metal
end rings through which project the ends of the small cast iron cylinder. An alloy
of lead and antimony is then run in through a hole in the upper ring so as to fill the
annular space between the copper cylinder and the interior cast iron cylinder whereby
the union of the two is effected. The casings are then removed from the finished
cylinder and the ends of the cylinder are turned in the lathe.
The following are details which may be added to the foregoing description;
(1) When metallic relief surfaces are to be directly produced from the intaglio
plaster moulds before referred to, the latter after being dried are dipped into a heated
bath of melted wax so as to be impregnated in an upward direction. The plaster
moulds are then removed from the bath, cooled, and immersed in water until saturated,
after which they are drained and the surface washed by pouring on it strong alcohol
in order to remove the last traces of air which might remain in the fine parts of the
design. The plaster moulds are then immediately immersed in a silver reducing bath
in which the metallization is effected in a uniform and perfect manner, the electro-
typing being effected on leaving this bath by immersing in the, ordinary copper
bath.
(2) When it is desired to reproduce a previously existing plate from embossed
counterparts in leather, paper, or other fabric, etc., one similar in every respect to the
first may be obtained without recourse to the original drawing, by proceeding in the
following manner; The embossed fabric, leather, or paper, is impregnated with an
alcoholic solution of gum-lac and allowed to dry thoroughly; it is then wetted by
dipping in water and gauged plaster is then run on its wetted surface and spread evenly
thereon. When set, the plaster cast is detached from the original and the subsequent
operations are then the same as before.
(3) The processes in use for backing up small electrotypes may be employed, but
in certain cases where, for example, the plate is required to be heated while in use,
unequal expansion takes place and consequent distortion. The following method is
therefore adopted for plates of all dimensions. The back of the electro is tinned
after protecting the "engraved" side as usual, the tin filling the cavities to a level
only with the projecting parts. After cooling, the face of the "engraving" is covered
with a protective sheet of gutta-percha after which the tinning and projecting portions
of the copper are laid bare by means of a coarse file. It is then dipped in au
alkaline bath to ensure the necessary adhesion and afterwards in the ordinary. electro-
typing bath where it is backed up to the desired thickness; care being taken to

page_text: ensure an even deposit in order to avoid the labor of subsequently levelling. The
same method is adopted for large size plates, except that an apparatus is used for
preventing distortion during the operation. This apparatus, which resembles a field
harrow in appearance, is made of rectangular form and composed of a series of
parallel iron bars connected by cross-bars and provided with movable teeth or pins
placed about four inches apart which are adjusted at the desired height by means of
set screws. It is supported at the four corners upon fixed legs.
When it is desired to tin and level the back of a large "engraved" plate, it is laid
with its protected face downwards upon a cast iron plate of the same dimensions or
rather larger, and heated by means of gas jets. The apparatus above described is
then applied over it with the pins at its four corners resting upon the cast iron plate,
and all the pins are then adjusted so that their blunt points shall bear freely upon any
part of the back of the plate and fixed in that position. The cast iron plate is then
heated and when the copper is at the proper temperature, the tinning is proceeded with,
to level the whole surface. If the pressure of the apparatus is insufficient to prevent
the plate getting out of shape, it may be increased by temporarily placing weights
upon it. The small cavities left after cooling at the points where the pins have rested
are filled with the same alloy by means of a soldering iron. The entire surface is
next filed and the engraved side protected in readiness for immersing the plate in the
electrotyping bath.
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
1st. The non-extensible tissues herein described, employed as a foundation for
photographic gelatine films whereby distortion is prevented in subsequent manipulations,
as specified.
2nd. The combination of improvements in developing bichromated gelatine prints
and obtaining moulds therefrom, as described.
3rd. The method of impregnating dry plaster casts or moulds and afterwards
metallizing them in a metallic reducing bath, as herein described.
4th. The employment of a gutta percha film, prepared as hereinbefore described,
for producing moulds or matrixes, in the manner described, for the production of flat
or cylindrical "engraved" surfaces for printing from, as specified.
5th. The gutta percha coated fabric herein described and its employment for
producing counterpart moulds by pressure for use in the production of deeply
engraved" surfaces for embossing or producing relief impressions on flexible
materials, as specified.
6th. The herein-described methods of curving either the moulds made of fusible
alloy or the flexible moulds before described, for the purpose of cheaply producing
truly cylindrical scamless printing cylinders, as specified.
"
7th. The herein described methods of producing flat or cylindrical "engraved
surfaces for printing from, by successive mouldings and the subsequent.combination of
the partial moulds to form a complete subject and the production of flat or. cylindrical
engraved" surfaces therefrom, as described.
8th. The herein described means of producing an "engraved" plate from embossed
leather, paper, or other. fabric.
"
9th. The herein described method of preventing distortion in tinning and backing
up the
engraved plates of all. dimensions by means of a pressure frame. with
adjustable pegs..
10th. The herein described method of bringing the herein described metal moulds
to a truly cylindrical form by pressing them into a truly bored cylinder by
means of half cylindrical cores and of a wedge driven in between them, as
described.
"surface
11th. The herein described method of converting any flat "engraved
into a true cylinder suitable for printing from, whatever may be the irregularities of
its surface.

page_text: 12th. The herein described method of producing other " engraved" cylinders from
a cylindrical relief surface obtained by electrotypy.
"
13th. The herein described method of producing from an engraved" cylinder,
others exactly similar thereto, as specified.
Dated this 27th day of June 1889.
A. MICHAUD.
By A. M. & Wm. Clark,
53, Chancery Lane, London, Patent Agents.