Engraving, Stereotyping, and Electrotyping Purposes.
Year: 1887

page_text: [Communicated from abroad by HOKE ENGRAVING PLATE COMPANY (Incorporated),
of Saint Louis, Missouri, United States of America, Manufacturers.]
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Engraving, Stereotyping, and Electrotyping Purposes.
I, WILLIAM ROBERT LAKE, of the Firm of Haseltine, Lake and Co., Patent
Agents, Southampton Buildings, in the County of Middlesex, do hereby declare the
nature of this Invention to be as follows :-
My Invention relates generally to that class of plates for engraving which consist of
a soft, friable coating upon a harder base and which are chiefly used in the production
of matrices for stereotyping and electrotyping purposes.
The present Invention also comprises improvements both in the coating and in the
base of such plates and in an improved process of making the plates. The improved
coating is composed of a finely powdered substance and a soluble mineral bond. I
prefer to use an insoluble inorganic substance like tripoli, chalk, glass, soapstone, talc,
barytes, or a mixture of such substances, for the body of the coating. The bonds I
prefer are the soluble mineral bonds, and of these the best are those known to chemists
as the soluble glasses, and of these I consider silicate of soda and silicate of potash the
most desirable.
The improved coating may be used in lieu of any other coating heretofore used for
engraving plates of the class under consideration, and it is superior to any other. It
is used in combination with several different kinds of base-plates. The essential point
in the base-plate so far as the engraving alone is concerned, is that its upper surfaces
shall be smooth and harder than the coating. I prefer that it should be of a darker
color than the coating.
For stereotyping purposes I prefer to use a thin, steel base-plate having its upper
surface blued except where I desire to produce a type having lines and letters of
unequal depth. In such cases I prefer a friable base-plate like roofing-slate into

page_text: which the engravers tool may be made to penetrate but which will apprise the
engraver of the fact that he has reached it when his tool strikes it by offering more
resistance to the tool than the coating does. A base plate of a stoney nature is
also desirable where a type which will produce an impression like a lithograph
is desired.
I have found that the printing surface cast from a matrice will partake of the
nature of the surface upon which it is cast and print like a type made of such
material. Where the plate is intended to be used in making a matrice from which
to cast an electrotype I prefer to use a base-plate of glass. Where the coating con-
tains chalk or any other substance liable to be affected by the acid in electrotyping I
treat it with a solution of silicate of soda to harden and protect the surface, and finally
coat it with wax before placing it in the bath.
The said Invention also relates in part to the thickness of the base-plate used. I
have found that a thin base-plate is much better than a thick one for stereotyping
purposes, for the reason that a thin plate can when inserted in the casting-box, readily
assume the temperature of the said box and thus enable the molten stereotyping metal
to thoroughly enter all the lines of the matrice before being chilled.
The process of making the improved engraving-plates is substantially as follows;
I first reduce the substance of which I intend to form the body of the coating to a
fine powder. I then mix it with water and the bond in solution and spread the
mixture upon the surface of the base plate and dry it thereon preferably by means of
heat below the boiling point of water and above 100° F. It is not essential that it
should be placed upon the base plate and dried immediately after mixing. I prefer
to allow 5 to 15 minutes to expire after placing the coating on the plate before
applying heat. I have found it desirable to lay a plate of slate, about 1th of an inch
thick, upon the coating while it is being dried, or preferably a finished engraving
plate having its face slightly hardened by the application of a solution of silicate of
soda or potash. A plate of any porous, inorganic substance will however answer the
purpose very well, such as a plate of glass or metal, or other suitable substance,
porous substances being preferable.
By using the following formula a comparatively soft coating can be obtained
without covering the plate while it is being dried.
6 drams of common talc or fine soap stone.
3 drams of barytes.
21 cubic centimetres of water.
9 drops of silicate of soda.
The proportion of barytes may be varied from 3 to 6 drams or be entirely left out
and a corresponding weight of tale substituted therefor.
In either case from to 1 drop of silicate of soda is used to each dram of earthy
matter. The silicate of soda referred to in this Specification has a specific gravity of
1-275, silicate of potash having an equivalent strength has a specific gravity of 1.325.
The plate may be hardened by using more of the bond or a larger proportion of
barytes.
It is better to bake the plates in an oven when a covering plate is used; when no
covering plate is used it is better to bake in the open air. The covering plate should
not be applied to the coating until the said coating has solidified sufficiently to prevent
it adhering to the covering plate.
I sometimes vary the process by mixing the substance or substances intended to
form the body of the coating with water, and spreading it on the plate and drying it,
and then pouring a solution of the bond over the plate and allowing it to soak into
the coating and then applying heat. To produce the best results heat must be applied
after the bond is introduced and a plate must be laid upon the surface of the
coating when it is drying. I prefer to make the mixture for the coating of about the
consistency of batter so that it is barely thin enough to pour out of a containing
yessel, and so that some of it will stick to the sides of such vessel. I prefer to use

page_text: earths, or a mixture of earths, for the body of the coating, but metals which are not
chemically antagonistic to soluble glasses may be added to the mixture. Soluble salts
and the alkalies, including alkaline earths, are unsuitable. The clays are very
undesirable because of their tendency to crack when drying. The best results are
obtained where substances of a stoney nature are used like those mentioned which are
not soluble in water, and are not expanded thereby to any great extent. Where clay
is used I prefer to add plaster of Paris to prevent cracking in drying. The following
formula has been found to produce very fine results.
One dram pulverized silicate of magnesia.
Two drams sulphate barium.
Four minims pure solution of silicate of soda or potash of equal density.
Five cubic centimetres water preferably filtered or distilled.
I have also found the fact that an engraving plate of the kind to which the present
Invention relates should have the particles of its coating loosely and evenly bound
together, and that those particles next the base plate should be bound thereto more
strongly than the particles above them are bound either to them or each other. So
that the particles will separate from each other readily, and more readily from each
other than from the base plate, but will nevertheless adhere to each other and to the
base plate with sufficient strength to enable the artist to draw lines close together and
across each other without breaking away the coating between the lines. A coating
composed of a finely powdered inorganic substance such as the ones named, and
bound by means of a soluble, mineral bond in the proper proportions and made
according to my process possesses these desirable qualities.
Dated this 26th day of November 1887.
HASELTINE, LAKE & Co.,
45, Southampton Buildings, London, W.C.,
Agents for the Applicant.

page_text: Improvements in and relating to the Manufacture of Plates for
Engraving, Stereotyping, and Electrotyping Purposes.
I, WILLIAM ROBERT LAKE, of the firm of Haseltine, Lake & Co., Patent Agents,
Southampton Buildings in the County of Middlesex, 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 :-
Relief-types of the class to which the present improvement relates are cast, moulded,
electro-typed or prepared in a matrix formed of a composite engraving plate, consisting
of a base-plate having a plane, smooth hard surface, to which is applied a coating that
is softer than the base-plate and of pulverizable material which can be readily scored
and engraved by means of a graver and which crumbles under the graver, and the
matrix is formed by engraving the design of the desired type in the coating, the lines
engraved being extended through the coating to the base-plate beneath. From such
engraved matrices stereotypes were cast directly as carly as the latter part of the last
century. A coated plate, to be used as a matrix when engraved, was patented by
Hoffman in France in 1792. Like his successors, Hoffman used a comparatively soft
coating upon a hard base-plate, the thickness of the coating regulating the relief and
the base-plate equalizing the depth of the engraved lines. Palmer, Joyce and others
in Europe have substantially followed Hoffman, but all have failed to produce a
satisfactory engraving-plate for the purpose described. The various coatings which
have been devised are objectionable for many reasons and especially because the
particles of the coating cohere more to each other than to the base-plate, and
consequently the coating, when cut with the graver, scales from the base-plate and
chips, so that it is impracticable to form the cuts closely together, or to cross them, or
to do any but the coarsest work with the plates.
The object of this invention is to obviate this difficulty as well as to provide an
engraving-plate having other superior qualities.
The base-plate of my improved engraving-plate for stereotyping purposes is
preferably a polished blued steel plate of suitable surface. It withstands the heat
incident to stereotyping and its tint, when a light colored coating is used, presents a
marked and agreeable contrast to the coating and enables the engraver to readily
judge the effect of his work. For electro-typing purposes a base-plate of glass is
preferred. Glass is also an excellent material in combination with the special coating
preferred by me and hereinafter described and its transparency enables the engraver
to examine his work by holding the plate to the light.
For the coating of the plate a finely-powdered material such as a finely-powdered
earth or mixture of earths or other equivalent finely-powdered inorganic substance or
substances which will withstand the heat of molten stereotyping metal is used. The
more thoroughly and evenly the material is comminuted and the more marked the
contrast in colour between the coating and the base-plate the better is the engraving
plate adapted for the purpose in view.

page_text: The leading features of the improvement are, that the particles of the coating next
to the base-plate adhere thereto more strongly than the particles above them adhere
either to them or to each other, and that the coating is very friable and the particles
thereof very loosely as well as very evenly bonded together, so that they readily
separate without taking and without breaking away between the lines when the plate
is engraved; bonding the particles of the coating to each other and to the base-plate
with soluble glass or an equivalent soluble mineral alkaline bond; bonding the
particles of the coating to each other and to the base-plate by treating the. particles
with a solution of soluble glass or equivalent soluble mineral alkaline solution and
then baking the coated base-plate until the coating is dried; mixing together the
ingredients to be bonded, then adding a water-glass in solution or an equivalent
solution of a soluble mineral alkaline substance, and then baking or subjecting a base-
plate coated with the mixture to a heat beneath the boiling point and not under
100° Fahrenheit until the coating is solidified, after which the heat may be increased
without injury to the coating, the special combination of substances given in the
formula and used to form the coating upon the base-plate.
The accompanying drawing shows an engraving-plate constructed according to this
invention in which,
Figure 1 is a plan view, and,
Figure 2 is a longitudinal section of Figure 1 on the line 2, 2.
A represents the base-plate, and B the coating.
In engraving a design in the matrix it highly desirable that the engraver shall
be able to see distinctly the lines made through the coating and thereby judge correctly
the work being done. To this end the coating is made white or light colored, while
the surface of the basc-plate appears dark, and the end is more effectually attained by
employing a blued steel-plate for the base-plate.
The production of a perfect type requires corresponding perfection in the matrix in
which the type is cast or otherwise prepared. A plane, smooth, polished metallic
plate A, presents the surface required for the face of the type. To obtain a sufficient
counter for the type, the coating B must be of corresponding thickness, and to make
smooth fine lines, to make lines close together, and to cross the lines, the coating must not
break away between the lines nor where they cross each other. It is also desirable to
minimise the resistance to the point of the graver as it is moved through the coating.
It is also desirable for the coating to be very even and homogeneous so that whether
slightly harder or slightly softer it shall offer uniform resistance to the graver. It is
not only essential that the coating withstand the heat of stereotyping or the acid in
electro-typing but it is also very desirable that it resist the action of the water or of
the atmosphere, so that, whether recently made or for some time on hand, it shall be
capable of use, and the inerchantable qualities of the plate are enhanced if it is light,
portable and cheap. All these requisites, and most of them notably, are attained with
the improved coating the most suitable proportion of which is stated in the following
formula.
Of sulphate of barium (barytes) take two drams; of silicate of magnesia (French chalk)
one dram; silicate of soda four drops; and of water five cubic centimetres. This mixture
will cover to a sufficient thickness six square inches of plate. The more perfectly it is
mixed the better the plate. A good way to make the mixture is first to mix the earth or
earths in a finely-pulverized form with water and work and rub the ingredients in a
mortar until the mixture becomes smooth, and then add the solution of soluble glass and
mix it with the other ingredients as thoroughly as practicable. The mixture should then
be spread evenly over the base-plate, shaking it slightly to settle the coating evenly. The
coating should, after being placed on the plate, be dried by heat beneath the boiling
point and not lower than 100° Fahrenheit, and preferably between 180° and
190° Fahrenheit, until it solidifies, after which the heat may be increased as high as
300° Fahrenheit without injury to the coating. The object in keeping the heat
beneath the boiling point while the coating remains in a semi-liquid state is to prevent.
its boiling. The coating should be thoroughly dried. The coating at its top is usually
incrusted, and after the plate has cooled and before it is engraved the crust should be

page_text: scraped off and the coating made of a uniform depth over the surface of the base
plate.
When the coating is mixed very slowly, it may be baked at once; but otherwise it
should be allowed to stand after mixing for at least five minutes before baking, and is
rather improved by being allowed to stand longer. The object in allowing it to stand
before baking is to allow the air contained in the mixture to escape as far as possible
and to prevent the coating from curling up and cracking while being dried. To
prevent the crust from curling up and breaking, it may be covered, when partly dry,
with a piece of glass, slate or other substance which is a good conductor of heat. The
covering plate should not be placed on the coating until the coating has become dry
enough not to stick to the covering plate. The plate thus covered should then be left
to dry in an oven, so that the covering plate may become heated, and so evaporate
rapidly the moisture that settles on it from the coating underneath it. If the covering
plate were allowed to remain cool or cold the moisture would gather into drops and
fall back into the coating and so retard the drying process and injure the even
texture of the coating. In the first stage of baking the plate may be in an oven, or
on top of a stove or oven, at a temperature not exceeding 200° Fahrenheit, but when
covered and placed in the oven the temperature may be increased to 300° or more
without injury to the coating.
The above method of mixing and baking is not the only one that can be used. The
essential points are first to introduce the bond in the form of a solution into the body
of the coating, and then dry the coating upon the plate.
Instead of mixing the bond with the water and earths in the manner above
described, the mixture may be made without the bond and dried, with or without
artificial heat, upon the base-plate, and the coating may then he saturated with a
solution of silicate of soda containing from twenty five to fifty drops of silicate of
soda to an ounce of water, and then baked as above directed. In this process I
prefer to use twenty five drops of the silicate of soda to an ounce of water.
Though I consider the formula for the coating above given the best, it may be
widely departed from and good results still obtained, so long as the bond is of the
proper nature and is used in the proper proportion. I prefer to use the earths named
in the formula (silicate of magnesia and sulphate of barium) and in the proportions
given; but the proportions may be varied indefinitely and good, though inferior,
plates made. Either silicate of magnesia or sulphate of barium may be used alone in
place of the mixture though not so good. Sulphate of barium is somewhat undesirable
when used alone, because a coating made of it has a tendency to crack in drying.
The following substances are unsuitable as substitutes for sulphate of barium and
silicate of magnesia viz. :-first, all soluble salts; second, alkalies, including earthy
alkalies or alkaline earths; and, third, all substances incapable of withstanding the
heat of molten type-metal in stereotyping. All other solid inorganic substances
which can be reduced to a fine powder, except the metals, I call earths" and
wherever the word "earth
ог earthy" is used in this specification it should be
understood in that sense and subject to the above limitations. Among the substances
which I call "earths" is silica, sometimes called an acid," but for my purposes it
has all the qualities of an earth, and I find the silicious rocks especially valuable.
"
All kinds of light-colored earths may, when finely powdered, be used in lieu of the
ones named in the above formula, though they are far from being equally good.
Those which have the least attraction for water are the best. The clays are perhaps
the least desirable of all, because of their tendency to crack when drying. It is
desirable where they are used to mix them with an equal bulk of plaster-of-Paris or
with some other substance which will prevent cracks, as the bond will not perform
that function when used in the proper proportion.
The most desirable earths, naming them in their order of merit, are in my opinion,
the following; soapstone, tripoli, talc, quartz and chalk. They may be used singly
or in combination with each other or other white earths not named. Sulphate of
barium, though excellent when mixed with silicate of magnesia, is not so good as the
substances named above when used singly. I have obtained my best results by

page_text: mixing a very light with a very heavy earth, and consider that a good course to
follow. I consider the specific gravity of a mixture of sulphate of barium and silicate
of magnesia in the proportions named in the formula given the most desirable, and in
selecting an earth or making a mixture of earths an attempt to approximate the same
specific gravity should be made.
I have given the proportions of silicate of soda and water which I prefer to use
with the mixture of earths given in the formula, but both water and the bond may be
used in different proportions though the results will not be so good. From four to
six (6) cubic centimetres of water and from one to fourteen drops of silicate of soda
may be used with the mixture of earths given in the formula. Where, however, less
than two drops of bond are used, the plate is very poor, because insufficiently bonded.
Where more than eight drops are used, the coating is made too hard to be entirely
satisfactory and is more or less liable to break away from the base-plate when being
engraved.
The silicate of soda which I have used and which I have taken as a standard in
making out the formula given is the solution known commercially as "pure" silicate
of soda. It is not necessary that it should be strictly chemically pure. It sometimes
differs somewhat in density and purity from the usual standard, but I have never
known it to differ enough to make the above formula and directions inapplicable.
What is commercially known as
66 pure "solution of silicate of potash, and which
shares the name of "soluble glass" with "silicate of soda is a strict chemical
equivalent of silicate of soda, and may be substituted for it and the same proportions
used where the solution is of the same specific gravity as the pure solution of silicate
of soda. There are also other soluble alkaline mineral equivalents of silicate of soda,
as is well known.
The following rule may be taken as a guide in using the bond and water with
other carths or mixtures of earths than the mixture prescribed in my formula. The
amount of bond and water used should be the same as for an equal bulk of the
mixture of earths given in the formula. This rule is not exact, because the chemical
character of the different earths varies, but it will answer for practical purposes.
Another test as to the amount of water to be used is that the mixture when made
should be thin enough to pour out of a containing vessel, but no thinner than
necessary for that purpose. It should be of about the consistency of batter, so that
a small portion will cling to the side of the vessel from which it is poured. Clay is
an exception to the general rule as to the amount of water necessary. Where it is
used, only one half the quantity of water necessary for other substances should
be used.
Where more water than I have directed is used, the earths settle to the bottom and
the larger portion of the bond remains on top, so that there is an insufficient amount
of bond near the base-plate unless an unnecessary amount of bond is used. The
amount of bond directed to be used is what should be embodied in the coating.
I do not desire to limit myself to any special composition or bond. I was the first
to discover the desirability of bonding the particles of the coating very loosely
together and more strongly to the base-plate than to each other, as well as a method
of accomplishing that end. There are well-known chemical equivalents of soluble
glass, all of which may be used. Some are called "soluble glasses" though I only
use the term "soluble glass" in this specification as embracing within its meaning
silicate of soda and silicate of potash in solution, I desire to cover all equivalents.
Having now particularly described and ascertained the nature of the said invention
and in what manner the same is to be performed as communicated to me by my
foreign correspondent I declare that what I claim is :-
First As a new article of manufacture, an engraving-plate having a base-plate
with a smooth, hard upper surface and a soft, friable coating of minute particles of
powdered matter loosely bonded together and having those particles of the coating
next the base-plate more strongly bonded to it than the particles above them are
bonded either to them or to each other.

page_text: Second-As a new article of manufacture,' an engraving-plate composed of a base-
plate having a smooth, hard upper surface, a soluble mineral bond, and a soft friable
coating of fine earthy particles loosely bonded together and more strongly bonded to
the base-plate by said soluble mineral bond, so that the particles of the coating next
the base-plate adhere thereto more strongly than the particles above them adhere
either to them or to each other, as, and for the purposes, described.
Third As a new article of manufacture, an engraving-plate having a soft, friable
coating composed of minute earthy particles bonded together, and to a base-plate
having a smooth, hard upper surface of soluble glass, for the purposes set forth.
Fourth In combination with a base-plate having a smooth hard upper surface, a
coating composed of soluble glass, silicate of magnesia, and sulphate of barium, in
substantially the proportions herein recommended, as and for the purposes described.
Fifth In combination with a base-plate having a smooth, hard upper surface, a
coating composed of soluble glass and a mixture of pulverized earths of different
specific gravities, as and for the purposes described.
Sixth-The herein described process of making an engraving-plate having a coating
bonded by a soluble glass, consisting in introducing the bond in solution into contact
with all the particles of the coating and then drying the coating by heat, substantially
as described.
Seventh The herein described process of making and finishing an engraving-
plate having its coating bonded by a soluble glass consisting in reducing the earthy
matter used to a fine powder, and subsequently introducing the bond in solution into
contact with all the earthy particles of the coating, drying the coating on a base-plate
by heat, and finally removing the crust, all substantially as herein directed.
Dated this 24th day of September 1888
HASELTINE, LAKE & Co.,
45, Southampton Buildings, London,
Agents for the Applicant.