IMPROVEMENTS IN THE MANUFACTURE OF ARTIFICIAL STONE AND THE TREATMENT OF THE SURFACE OF THE SAME
Year: 1884

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I, HERBERT JOHN ALLISON, of 52 Chancery Lane, London, in the County of
Middlesex, Patent Agent, do hereby declare the nature of my invention for
IMPROVEMENTS IN THE MANUFACTURE OF ARTIFICIAL STONE AND THE TREATMENT
OF THE SURFACE OF THE SAME" (which invention has been communicated to me
from abroad by Jamos Lafayette Rowland, of Troy, in the County of Reusselaer and
State of New York, United States of America, gentleman), and in what manner
the same is to be performed, to be particularly described and ascertained in and
by the following statement:-
Many methods have been essayed to manufacture artificial stone or marble of
hydraulic cements and other materials suitable for mantles, table-tops, furniture-
slabs and various other articles which are made of the natural marbles or slate, but
from want of efficiency, cheapness, or practicability, none have given such satisfactory
results as to be generally adopted.
My present invention is chiefly to this end and for the purpose of obviating
previous objections, and by it I can cheaply manufacture an article closely
resembling natural marble but more closely natural slate and possessing more the
character of the latter, and which, therefore, I shall herein designate by the name
"Calcareous Slate." I can also by it cheaply manufacture stone of an appearance
and character closely resembling many of the various kinds of natural stone used for
building and various other purposes as for example, limestone, marble, freestone
and various other sandstones-which are suitable for the same uses, and superior
in respect to strength, texture, and durability to any which have been made.
This calcareous slate is suitable both for such articles as are made of natural
slate or marble, and for receiving with equal efficiency and perfection similar treat-
ment, in the way of having lines, grooves, and various ornamental designs cut or
carved in its exterior surfaces, and surface-coatings as of paints, varnishes, or the
process of marbleizing applied to it.

page_text: The invention consists, first of a new article of manufacture-to wit, a cal-
careous slate resembling and partaking of the character of natural slate, produced
artificially.
Second, of a new and useful composition of matter herein described and which is
compounded and used as set forth.
Next, of an improvement in artificial stone compounds which have calcined
calcareous matter as an ingredient or base of their composition, effected as and by
the means set forth herein.
And finally, of a process for improving the exterior surfaces of articles made of
Buch materials and combinations thereof as described herein.
The composition of these compounds as compounded for this slate, any one of
which may be used as may be preferred in its manufacture, and also as varied and
used in connection with other materials herein described in forming compounds for
the manufacture of stone with a resemblance to and with qualities characteristic
of freestone or other natural stone an imitation of which may be desired, or as used
and introduced into an artificial stone compound for the improvement of the same,
is as follows:
Ground or pulverized slate and one, or two or more, such as may be selected for
the purpose of the following named materials: hydraulic cement, hydraulic lime,
hydrate of lime, and quicklime; with which materials, when it is desired to imitate
closely a marble, or when a stone in imitation of limestone, freestone, or some other
natural stone is desired, are to be included these materials-to wit, finely ground
or pulverized marble, limestone, talc, sand or other equivalent material, or sand in
its natural state cleanly washed, and some one or more of the same such as may be
suitable and preferred for the purpose, used in connection with the powdered slate
mixed with one, or with two or more of the first named materials. The foregoing
ingredients are combined as and in such various proportions or quantities of each
as hereinafter setforth, though the specification will not be of such extent as to
represent all the various compounds suitable for the manufacture of articles under
this invention that may be formed by these modes of combining these materials,
such description being quite unnecessary.
I intend to give such a full and complete description of this my invention as to
make it known to others and to enable workmen who are skilful and have
experience in the art to which it pertains to fully comprehend and practically and
successfully carry out the same. And to this end I shall now proceed to state a
mode of preparing or adapting in state or condition the materials, hereinbefore
named, for compounds, the special end or purpose some of them serve in the same,
and such formulae as may serve for forming compounds, any one of which may be
used as may be preferred, for the manufacture of this slate, and also such as may
serve for forming compounds for the manufacture of stone in imitation of freestone,
limestone, or other natural stone the manufacture of which I deem practicable-in
this way illustrating the mode of formulating and compounding these materials-
a mode of making up the compounds as formulated and forming articles thereof,
and finally, a process of improving the exterior surfaces of the articles.
Formula for Compound No. 1.-By measure, four parts ground slate, four parts
Portland cement, one part (or any quantity from one-half of one part to one) of
hydrate of lime, and water, the latter in quantity sufficient to form with these a
homogeneous and compactly compressible paste or mortar. The mode of mixing
up this compound and forming articles thereof, is as follows: Mix the hydraulic
cement and hydrate of lime intimately with each other, as by passing them together
through a proper sieve for the purpose, add the ground slate and mix till the whole
mass has a uniform shade of color then apply the water-preferably in the form of
vapor or spray as by passing the water through a rose having many fine holes-
intermixing in the mean while with suitable rakes or otherwise as may be most
efficient for the purpose, continuing the intermixing till the entire mass has become
sufficiently homogeneous and of proper consistency to be packed or compressed
compactly. Then tamp or compress this resultant mixture in moulds of suitable

page_text: construction and shape to give articles the form desired, using proper care in the
operation to effect throughout the articles thus formed, so far as may be practicable,
perfect contact and connection of the particles with one another.
When relieved of the mould the articles are indurated and solidified, and this is
speedily and quickly accomplished either by treating them with proper applications
of water saturated with or holding in solution carbon dioxidido, or subjecting them
in a closed chamber to any one of the other carbonating processes described in the
patents for improvements in the manufacture of artificial stoue heretofore granted
and issued to me; or they may be gradually indurated and matured by the
carbonic-acid and water-vapor of the atmosphere and suitable applications to them
of water from time to time.
Formula No 2. Same ingredients and quantities or proportions as given in the
preceding formula, with this exception, one part (or any quantity from one-half to
one part) finely ground quicklime, or one part hydraulic line (lime of Fiel) is to be
substituted and used in the place of hydrate of lime. The mode of making up
compounds and forming articles thereof, is the same as stated above, care being
taken to perfectly slake the ground quicklime in the operation of making up the
compound.
Formula No. 3. Four parts ground slate, four parts Portland cement, water in
quantity as stated. Mix the slate and cement intimately with each other, add the
water and proceed as stated.
Formula No. 4. Four parts ground slate, four parts finely ground or pulverized
limestone or marble or sand, or two parts pulverized limestone or marble and two
parts sand finely pulverized, or two parts (or if it be desired four parts or a greater
quantity) of fine sand cleanly washed and two parts pulverized limestone or marble,
eight parts Portland cement, one part (or any quantity from one to two parts)
hydrate of lime or one part of ground quicklime, and water in quantity as stated.
Mix the ingredients, ground slate, hydraulic cement, lime and pulverized limestone
marble or sand (or sand or other equivalent material used) intimately with one
another and then proceed as stated.
Formula No. 5. Four parts ground slate, four parts (or any quantity greater
that may be preferred and deemed practicable) fine cleanly washed sand, Eight
parts Portland cement, two parts or one part hydrate of lime or one part ground
quicklime, and water in quantity as stated. Mix the ground slate, cement, lime,
and sand intimately with one another and then proceed as stated.
Formula No. 6. Four parts ground slate, four parts fine sand cleanly washed, or
two parts sand and two parts pulverized limestone or marble, Eight parts Portland
cement, and water in quantity as stated. Mix all the solid materials with one
another till the mass has a uniform shade of color, then add the water and proceed
as previously stated.
As to the mode of preparing these materials and the special end some of them
serve, I may state that for obtaining the most efficient results thoy should be in a fine
state and all coarse grains or parts excluded from them; those in the hydrate of lime
being usually gritty and partially slaked parts, and in the hydraulic cements and
limes portions of over burned materials or aggregations of injured particles and
deleterious to a composition. I usually therefore, pass the hydrate of lime through
fine bolting cloth, and the hydraulic limes and cements through a sieve having
meshes sufficiently fine to exclude such parts, and in like manner (according to the
degree of fineness desired in the materials) screen all the other materials used. For
instance, for obtaining the most efficient result with the compound expressed by
the Formula No. 1, I, after mixing all the ingredients as stated, before applying
the water pass the mass through a sieve having seventy meshes to a square inch of
surface and then proceed as stated.
The ingredient, ground slate, upon the combination of which with a calcined
calcareous base-in this way forming a compound whereof the slate described
herein is in the manner described produced-or its combination with such base and
then mixed and used as stated in connection with such materials as described; or

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its introduction into artificial stone compounds of the character described for the
improvement of the same. My invention chiefly depends for the improvements
in respect to the texture, quality of grain, strength, compactness, and durability
effected in the stone or concretions which are thus produced is to be of the best
quality and finely ground.-[The term "calcined calcareous base as here used, or
where hereinafter throughout this specification or in claims appended thereto it
may be used, I may here state, I intend shall mean a base consisting of one or of
two or more of such materials as first herein named--to wit, hydraulic cement,
bydraulic lime, hydrate of lime, and quicklime].
The ingredient hydrate of lime is to be in the state of an exceedingly fine or
impalpable powder. This material, so also, the ground quicklime (after being
perfectly slaked in the mixture) besides serving on becoming indurated in the
manufacture as a cement, serves previously to this in its moistened state, in the
operation of compressing or compacting the compound in the mould in forming
articles, as a lubricant to the grains or particles of solid material with which it
is combined, whereby greater density and strength are given to the articles.
The hydraulic limes and hydraulic cements to bo used are not necessarily of the
kinds particularly named in the formulae or compounds herein given, as some ono
or some two or moro mixed with one another, of any of the hydraulic cements of
good quality and known merit may be successfully used in lieu of Portland cement
or may be mixed with an equal quantity of the latter or in other proportions, and
this resultant mixture be used in the same proportions with the ground slate and
other ingredients as a Portland cement.
So, also, in like manner, the ingredients ground quick lime and hydrate of lime
or hydraulic lime may be mixed with one another and the resultant mixture bo
used as a hydrate of lime-in the same proportions with the other materials-And
this method of combining these limes and their use in this way in a compound
I deem highly advantageous providing they are perfectly slaked in the compound
before proceeding to form articles of it.
For the improvement, as hereinbefore stated, of an artificial stone compound of
the character described by the introduction of the ground slate into its composition,
I add, and, intimately intermix with the compound which is to be in this way
improved, usually, a quantity of the slate equal to one-half or three-fourths of or
one equal to the cementitious base of the compound.
To obtain in articles a color not obtainable with materials such as are herein
named, suitable mineral pigments-as the metallic oxides-may.be used for this
purpose by intimately mixing these with the ingredients of the compound in proper
quantities to give the color dosired.
In articles which are to have a fine quality of grain and closo texture, the
purpose to this end served by preparing the solid materials as described and having
all these in a fine or finely pulverized state being well understood, it only remains
to state that when an article is to serve for any special use requiring it the com-
position or compound for such article is to be forinulated specially in view of such
use, such inaterials and proportions selected for combination with the ground slate
as may be most suitable for the article or some one of the formulae herein given
adapted to this purpose by altering the proportions of some one or more of its
ingredients as for instance, tile for floors and areas-These articles requiring
unusual hardness, from twenty-five to one hundred per cent, more hydraulic lime is
to be used than is expressed in the formulae, herein given.
Some articles, when for any reason it may be deemed desirable,-
-as for instance,
the reduction of the cost-need not necessarily be made wholly but in part only, of
such compounds as are indicated by the formulae given in order to serve efficiently
the uses for which they are intended, and such articles may consist of a facing of
suitable thickness made of some one of these, and a backing suitable to complete
the thickness and strength required in the article, made of some courser and cheaper
composition that may be suitable for the purpose, as for instance, some one of the
usual concrete compositions, and some articles such for instance as tile for floora

page_text: and areas, and wainscoating and some other articles which are to be placed or
imbedded in mortar, cement, or plastic, and held in place by the same-are pre-
ferably made in this way with a backing of the coarser compositions, because the
plastic or mortar more readily and firmly adheres to such backing. In making
articles in this manner, care must be taken to join or incorporate most perfectly the
facing with the backing at their contact surfaces.
To form an article in this manner as for instance tile for floors and other
uses I usually proceed as follows: I put lightly in the mould a quantity of the
compound intended for a facing sufficient for such facing levelling it without com-
pression, and, if it be desired, slightly corrugating or indenting the same in n
manner most suitable for incorporating with it the inaterials for a backing, which
is next to be put in the mould. Then I put lightly and evenly in the mould such
a quantity of the composition intended for backing as will give, without any
additional supply, the thickness and strength required, and with hydraulic or other
suitable mode of compression from the article.
The process of improving the surfaces of articles made of such compounds as
described, in this way adapting them for receiving a polish or paints and varnish,
or the process of marbleizing with the greatest efficiency, is as follows; I tako
either a chloride of lime or hydrate of lime, usually the latter, prepared as herein-
before stated, the same being free from gritty and unslaked particles, and by
intermixing this with water form a liquid sizing of proper consistency for being
freely applied, and so far as may be practicable, freely absorbed by the surfaces to
which it is to be applied. I then coat the surface or surfaces of the articles which
are to be improved in this way with this sizing, doing this in any suitable manner
for adapting the coating to the treatment it is subsequently to receive in the
process.
A simplo mode of applying the sizing to the surfaces is to make the application
with a woollen cloth gathered into a bunch, dipping a portion of this into the
sizing as frequently as the operation may require and rubbing the portion, thus
taken up, to the surface, going over the entire surface or the portions which it is
desired to improve in this way. The application thus made is then rubbed to the
surface, being kept suitably moistened with water to prevent its drying too rapidly
for its proper adhesion to the surface, and finally gently smoothed to and made to
conform with the surface. Prior to applying the sizing the surfaces may be gently
smoothed with fine sand-paper.
After the coating has become attached to the surfaces with sufficient firmness for
the next step in the process, as it will quickly do when the articles to which it is
applied are submitted to some one of the carbonating processes herein before
referred to, or as it will gradually do in drying and hardening in the atmosphere,
but not with the same efficient result, I proceed, using proper tools, usually a stone
with a true surface or suitable in shape for the purpose, such stone being of very
fine grit, to rub down the application uniformly and to such extent as may best fit
the articles for the uses for which they are intended, or for receiving any
subsequent treatment which it is intended they shall have, it being understood that
water is used in such quantities as may be required. This accomplished the articles
are properly dried, and such as are to have coatings, as of paints and varnishes, or
the process of marbleizing applied to them, may then be treated in making such
applications the same as similar articles made of natural slate or marble. In this
operation of rubbing down a coating of the sizing proper care is to be used not to
penetrate the surface with which it is incorporated, and this is easily to be avoided,
since water when used in proper quantities and not too freely, forms with tho
particles detached from the coating by the rubbing, a slippery substance that serves
efficiently to this end.
Such coating properly applied to articles having surfaces in quality and otherwise
suitable for its application, may be rubbed down to such extent as to appear as
slight aggregations of particles of the sizing filling interstitial spaces and defective
portions in the surfaces, and this mode of treatment of the coating by reason of

page_text: its effecting very great smoothness in the surfaces and also rondering them nearly
non-absorbent of water and other fluids, I find to be highly efficient and practicable
for adapting surfaces of articles which are to be marbleized for receiving the process
with the greatest efficiency.
In the case of articles made of the coarser artificial stone compounds the filling a
of the interstitial spaces and defective portions of their surfaces in this way renders
them less absorbent and less pervious to water and other fluids.
In forming the sizing, if it be desired to facilitate the hardening or indurating
after its application to the articles, a hydraulic cement in a very fine state may be
combined with the hydrate of lime, but not in such quantities as may affect the 1
efficiency of the sizing for the purposes for which intended, and if it be desired to
give the sizing any particular color suitable dyes and pigments for the purpose
may be mixed with it.
Having thus fully described my invention, I may state that I do not intend to
confine my invention to the precise proportions of the materials and combinations 1
represented in the formulae or compounds herein given, having on the other hand
provided for some changes in these as for instance, in such cases as hereinbefore
stated.
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
I claim is
⚫ 1. An artificial stone, herein designated by the name "Calcareous Slate," con-
sisting of powdered or ground slate mixed with a calcined calcareous base the
whole being set with water substantially as described.
2. The method herein described of forming artificial stone, which consists in i
setting a calcined calcareous base with which ground or powdered slate has been
mixed in the proportions specified, with water, substantially as described.
3. An artificial stone consisting of ground or powdered slate and a calcined
calcareous base intermixed with pulverized limestone, marble or sand, or other
equivalent material, or sand in its natural state the whole being set with water
substantially as described.
4. As an improvement of artificial stone compounds composed of sand or other
equivalent materials mixed with calcined calcareous matter, as hydrate of lime or
quick-lime, hydraulic cement or hydraulic lime, the introduction therein of
powdered or ground slate substantially as herein set forth.
5. The herein-described composition for the manufacture of artificial stone,
which consists of ground or powdered slate mixed with a calcined calcareous base
substantially as described.
G. The process of improving the surfaces of the artificial stone, herein described,
which consists of applying a solution of chloride of lime or of hydrate of lime to
such surfaces, substantially in the manner specified.