Improvements in and relating to Artificial Stone known as Reconstructed Granite, and in Process of Making the same.
Year: 1898

page_text: Date of Application, 9th Aug., 1898-Accepted, 22nd Oct.,
1898
COMPLETE SPECIFICATION.
Improvements in and relating to Artificial Stone known as
Reconstructed Granite, and in Process of Making the same.
I, WILLIAM COURTENAY, a Citizen of the United States of America, of 14.
Dey Street, in the City and County of New York, in the State of New York, United
States of America, Manufacturer, 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;-
-
This is an improvement on what is described in British Patent 7,184 of 1891,
and the improvement consists not only in the different mode of and mechanism for
making reconstructed granite blocks, but in a new and improved article or product.
To carry out my process I take granite, in the form of granite chips or blocks,
or any convenient form, and calcine the same by intense heat. The granite is then
pulverized, and by sifting, grades of different fineness may be obtained. The
pulverized granite is then mixed with other ingredients in about the following
proportions.
For the inner portion or body of the blocks, a mixture of say 100 parts of the
pulverized granite, 10 parts ground feldspar, and 40 parts fire clay is made,
with the addition of enough water to make the mass plastic. This produces a
highly refractory composition, which will not melt under a much higher tempera-
ture than that to which the blocks are exposed in the kiln.
For the ornamental face, surface, or outer skin of the blocks, a different com-
position is made, consisting, say, of 100 parts of the pulverized granite, 30 parts
of ground feldspar and 20 parts fire clay, with water added. Such a composition
can be thoroughly fused at temperature from about 2700 to 3000 degrees
Fahrenheit, as nearly as I am able to ascertain.
The refractory body of the block may be molded to a size somewhat smaller
than the desired block, either by hand, or in a mold, and the facing or coating of
the fusible material may be applied to certain faces thereof, to the thickness of
say about one-fourth of an inch, and the block then pressed in a mold; or the
mold may be lined on certain faces with the fusible plastic material and the
body filled in with the more refractory material, so as to give the ornamental or
exposed faces a coating of the fusible material; and this coating will generally
not be of great thickness, say one-fourth to one-half an inch on blocks four inches
or more in thickness and a foot or more in other dimensions. But I do not desire
to limit myself in the proportions of these refractory and fusible portions of the
block. It is, however, advisable to make the fusible coating no thicker than can
be fused by the kiln or furnace heat in burning.
The granite may be said to form the base or main substance of the blocks, the
clay a binding agent and the feldspar a flux; although this may not be entirely
accurate, as the action of heat on the different materials at different temperatures
is not fully understood.
The blocks having been shaped to the desired form, are dried sufficiently to
retain such form in the kiln or seggers. The ornamental faces of the blocks may

page_text: then be sprayed with a glazing mixture, such as is used in glazing stoneware
or pottery. The glazing mixture, such as zinc white, white lead, or other glaze
fuses at a low temperature, and both in and out of the kiln prevents discoloration
of the blocks by the oxidation of iron or other impurities which may be in the
granite. The glazing mixture is used in almost imperceptible quantites, not for
the purpose of forming a glazed surface, in the usual sense, but for the prevention
of discoloration, and is effective for that purpose. It may be applied to all the
faces.
The blocks having been-prepared as above, either with or without the glazing
compound, may be placed in a kiln, as would be the case with bricks, for burning.
The kilns are then fired, and a temperature approximating 3000 degrees F., more
or less, maintained until the outer fusible coating is thoroughly vitrified and the
body of the block baked or burned. The time required for burning depends on
the composition and on the conformation of the blocks. The temperature should
not be high enough to fuse the refractory body of the block, but should fuse the
less refractory surface.
In some instances the blocks may be placed in seggers, and fired, as usual in
burning pottery. As a substitute for seggers. as ordinarily constructed, 1 have
devised a plan of supporting a number of blocks-in open frames, which I will now
describe.
Figure 1 of the drawing indicates a section of one of the blocks; A indicating
the inner refractory material; and B the outer coating of more fusible material.
Figure 2 shows a pile for the kiln; C, C, indicating tiles; 1), corner supports,
and B the composition blocks.
Figure 3 is a pile with two rows of blocks.
By taking the flat tiles C, C, of fire clay, of large size, the top and bottom
plates of the pile may be readily formed. Between these plates. two or more
rows of blocks B may be enclosed, and the blocks may be placed upon each other
two or more courses in height, with sand between the courses. Upright pillars D,
of firebrick, support the plates C, so that the composition blocks B have but little
or nothing beyond their own weight to support. A slight space is preferably
left between the blocks and the upper tile, for heat circulation. Strips of asbestos
paper E are placed over the faces of the blocks B, or over the joints, the edges
of these strips being held by turning under the edges of the blocks. The asbestos
paper protects the face of the blocks from the direct action of flame or heat,
and thus preserves the color and texture.
The piles of blocks formed in this manner may be built into kilns of almost any
size, and the blocks burned in such kilns are produced at much less expense than
when burned in seggers, as ordinarily constructed, since the space occupied is
much less, and the loss from breakage much reduced. The blocks are also better
supported.
In laying up blocks in ordinary kilns, the ornamental faces of the blocks may
also be protected by strips of asbestos paper, which strips may be held by turning
in the edges between the blocks, or under the edges thereof.
Where all the edges of the blocks are of ornamental character, as in balustrades,
and the like, the asbestos paper may pass entirely around the block. The sheet
of asbestos paper prevents what is known as fire flashing" or the discoloration of
the blocks in whole or in part from burning in the kiln or furnace, and also pre-
vents cracking from uneven temperatures.
The glazing compound is applied solely for the purpose of preserving the color,
and is a mere film, and is not such a glaze as is applied to tiles, pottery and
vitrified brick. After burning, this thin glossy film is generally removed, either
by a sand blast, or by treatment with a solution of hydrofluoric or other acid,
and washing with water, leaving the blocks lusterless, like natural stone.
I
propose to avail myself of known, compositions and processes in this art. The 5
proportion of material and the modes of manipulation may be changed within the
limits of my claims without departing from my invention.

page_text: I have described the process as applied to reconstructed granite, but it is
apparent that some other varieties of stone may be treated in like manner.
Heretofore, in making reconstructed granite from homogeneous material, it
has been found needful to employ a very high temperature in burning, and the
loss by breakage and distortion has been very great. By making the outer surface
of the blocks of a more easily fusible material than the interior, I secure absolutely
better blocks at a less expense. The ornamental face is like natural stone, but
is impervious to moisture, and practically fireproof, while the body of the block,
not having been fused, adheres readily to the cement.
Having now particularly described and ascertained the nature of my said
invention and in what manner the same is to be performed, I declare that what I
claim is-
1. A composite building block having the appearance of granite, the main
body of the block being of granite, clay, and a minimum of flux and the face
being of different proportions of the material with an excess of flux, said face
being solidified by fusion of the flux.
2. A building block having its main body composed of granite, clay, and a flux,
and its ornamental face composed of granite, clay in less proportions, and flux
in greater proportion, the flux in the face portion only being in a solidified con-
dition due to fusion.
3. A building block composed as to its body of granite, clay, and a minimum
of flux, its face of granite, less clay and a maximum of flux, said face compacted
by fusion, and having a glazing over said face.
4. The method of producing building blocks of granite appearance, which
consists in pulverizing granite, mixing the fine granite with clay and a flux,
forming the body of the block of the said ingredients with a minimum of flux,
and the face of the said ingredients with a maximum of the flux, and burning
the block until the face is fused and the body baked but not 'fused.
5. The method of producing building blocks which consists in pulverizing
granite, mixing the fine granite wth clay and a flux, forming the body of the
block of the said material with a minimum of the flux, and the face of the said
materials with a maximum of the flux, glazing the face, and burning to 'first fuse
the glazing and then the face composition, leaving the body unfused, but baked
or burned.
6. The method of forming artificial granite blocks, with ornamental faces,
which consists in molding the body of the block of a compound of granite, clay
and a flux, and molding the face thereon of like materials, but in different propor-
tions, so that the face contains an excess of the flux, protecting the face by a
non-combustible covering, and firing to the extent that the facing, under the
covering, is fused, the body of the block remaining unfused.
7. The method of producing artificial granite blocks, which consists in molding
the body of a compound of granite, clay, and a flux, molding the face of a
compound of granite, clay, and an excess of flux, covering the face with a glazing
composition, burning to first form the giaze and then to fuse the flux in the
facing, and after cooling removing the glaze.
8. The novel pile for burning artificial stone blocks, wherein the bodies are
supported by tiles and firebricks, and the faces covered and protected by asbestos ⚫
paper in manner stated.
Total th
L
1
P
JENSEN & SON,
77, Chancery Lane, London, W.C., Patent Agents.