Improved Manufacture of Material suitable for Building and Architectural Purposes, and for Ceramic and other similar Works.
Year: 1892

page_text: Date of Application, 2nd June, 1892
Complete Specification Left, 13th Feb., 1893-Accepted, 29th Apr., 1893
PROVISIONAL SPECIFICATION.
Improved Manufacture of Material suitable for Building and
Architectural Purposes, and for Ceramic and other similar Works.
I, MARC LAFFONT of 95 Boulevard Beaumarchais, Paris, in the Republic of
France, M.D., do hereby declare the nature of this invention to be as follows:-
Very small residues of various species of eruptive rock have before now been
obtained in laboratories by melting either certain chemicals or the component
substances of the rock itself at a temperature which has never been less
than 1050° C.; this minimum temperature, indeed, applying to rock the component
parts of which are most fusible; but in most cases the temperature had to be raised
to from 1300 to 1600° C. and upwards, while in no case have so quite fireproof
materials been employed.
Now it is an unquestionable fact that eruptive rock might become a very superior
building material but for the difficulty of hewing it and its great hardness. I have
therefore endeavoured to reproduce this material artificially, on a large scale, and
in the final form in which it is ready for immediate use, and I intend to introduce
the new material under the name of "pyrosilex." I will now proceed to describe
its manufacture.
From an economical point of view, the manufacture of artificial eruptive rock
from chemicals, or from the dust of the rock itself, is evidently quite out of the
question, considering the great expense it would involve.
But, chemistry, mineralogy and the study of geological strata instruct us that
the different kinds of clay are neither more nor less than sedimentary or eruptive
rock, more often eruptive, modified and disintegrated through meteorological
influences. I have therefore selected clay as a component element of the artificial
eruptive rock.
Considering that the changes undergone by igneous rock through meteorological
influences result in the disappearance of its original properties, while in the incan-
descent condition it becomes consolidated, my first operation consists in baking or
calcining the clay at a high temperature. For this purpose I employ, not the
powdered clay known as fire-clay (which only consists of hydrated silicate of
alumina containing more or less moisture and a slight tincture of oxide of iron or
of alkaline salts or earths), but what is known as fusible clay, containing larger
quantities of oxide of iron (from 3 to 10 per cent. and more) lime (from 3 to 10 per cent.
and more), magnesia, alkalies, and sometimes a certain amount of manganese;
in other words I preferably use clay containing all those elements which constitute
eruptive rock. To prevent the clay, subjected to the action of the fire, from
undergoing an undesirable alteration or deformation by melting, after it has been
calcined, (when it is desired to give it a definite form with a view to immediate
use) I adopt the methods commonly in use in the pottery and tile manufacture.
In order to obtain material similar to eruptive rock, I therefore employ a mixture
of calcined fusible clay and of crude fire-clay; or a mixture of dust of eruptive
rock, of grit or sandstone, of clay-slate or ordinary slate or of sand resulting from
the disintegration of rock, with crude fire-clay, in proportions varying according to
the nature and properties of the mixed substances. The mixture is first made in a
dry condition and then moistened and stirred; and this is repeated as many times
as is necessary to attain the desired degree of plasticity; the plastic mass is then
thoroughly dried and baked at a high temperature.
White heat should in all cases be attained; that is to say that the temperature
should never be less than 1250° C., but may, according to the degree of infusibility,
be much higher. At less than 1250° C. " pyrosilex can not be obtained by this
procoRR

page_text: (1) INITIAL PHYSICAL CONDITION OF THE MATERIALS TO BE TREATED.
It is well known that the more finely a substance is divided, the greater surface
it offers for the action of other substances with which it is combined or compounded.
It is therefore necessary that the substances to be treated by this process should be
dry, and in the condition of powder. After they have been mixed in the dry state,
they should be stirred two or three times over in suitable vats or tanks, so that
they are uniformly moistened and kneaded and may acquire the desired plasticity
and consistency. This pulpy mass is then, for a space of time which may vary
according to circumstances, allowed to rest in a place where its degree of moisture
cannot vary. Moulding is next proceeded with; the mass when introduced into
the moulds, being either hard or soft, the latter being preferable.
(1) The fire-clay to be employed is first selected: It may be of any suitable
kind, provided it is dilutable, inalleable, plastic, and as free as possible from foreign
bodies (such as alkalies, lime, magnesia, oxide of iron or the like). After being
dried this clay is reduced to powder and sifted. For convenience I shall herein-
after refer to this powdered clay as the plastic substance.
(2) On the other hand any of the following materials may be chosen according
to local circumstances, facilities of conveyance, cost of production, etc.; which
materials are also reduced to powder and sifted :
(a) Fragments of eruptive rock of various kinds such as protogyne, eurite,
retinite, obsidian, compact syenite, compact fine-grained porphyry, serpen-
tine, trap, melaphyre, dolerite, basalt, etc.;
(b) Quartzy sandstone or sand;
Clay-slate or ordinary slate;
(d) Fusible, non-marlaceous clay previously calcined or baked (such as chips
or waste from brick-yards).
One of these materials, no matter which, is powdered and sifted; and in referring
to it hereinafter I propose calling it the fusible material.
(3) The plastic material and the fusible material are now mixed together in pro-
portions varying according to the nature of each, which may be readily ascertained
by preparatory experiments (made, say, in a muffle-furnace), the scale of comparison
being, on the one hand, 1, 2, 3, 4 or 5 parts of plastic material, and on the other
hand 5, 4, 3, 2 or 1 parts of fusible material.
(4) After thoroughly mixing the two materials, the mixture is moistened and
stirred so as to make it homogeneous and ensure uniform moisture throughout. The
stirring process is preferably interrupted several times, as intermittent stirring will

page_text: better develop the plasticity of the moisture. When stirred the mass should, until
it is required for use, be kept in a place where its degree of dampness can undergo
no alteration. At this stage the material shall hereinafter be referred to as the mass.
(5) The mass may be differently employed, according to the purpose it is to
fulfil or the kind of goods it is desired to manufacture.
(a) For decorative (stamped, moulded, or turned) pieces, or for hollow
articles, such as pipes each article is made in one operation and then directly
conveyed into the drying chamber.
(b) In the case of solid blocks, such as bricks, paving-stones, slabs, etc., the
mass is first placed in moulds and introduced into the first drying-chamber,
where it is left until, under a strong pressure of the finger, it shows a slight
mark. It is then ready to go to the press, and upon being pressed, it is
taken to the second drying-chamber.
A rough mixture, in which homogeneity is disregarded, may yield a mass of
different composition, and the final product will be pyrosilex of variegated appear-
ance, having streaks, veins, or bands of different colours.
Or silex, quartz, broken clinker, or any other infusible material may be embodied
in the outer surface of the moulded article to diversify its appearance.
(6) When the articles are thoroughly dried, they are placed in the kiln and in
doing this, care should be taken that the flame can always freely circulate around
the goods. And it will here be observed, by the way, that as the different articles
of pyrosilex are always obtained at a white heat, or at a temperature never less
than 1250° C. and do not consist of mere physical modifications of matter, as is the
case in ordinary ceramic goods, pieces of various size and thickness may simul-
taneously be introduced into the kiln without the risk of burning some and of not
baking others sufficiently.
Ordinary bricks are obtained by the physical change undergone by the material
used; from adhesive and plastic it becomes tough and hard, owing to the increased
hardness of the closely compressed and intermixed molecules; whereas pyrosilex
is the result of chemical action and cannot be produced at a less temperature
than 1250° C.
The fire should be attended to as follows:-
For 12 hours a low fire should be kept up, to obtain a thorough desiccation of
the goods by the elimination of moisture therefrom. It should, however, rise by
slow degrees and at the twelfth hour incandescence should commence, at a
temperature of about 525° C. From the 12th hour onwards an ever increasing
heat is kept up, say according to the following (Pouillet's) scale:
14th hour 700° C. (melting point of aluminium) deep red-heat.
16th hour-800° C. nascent cherry-red.
18th hour-900° C. deep cherry-red.
20th hour-1000° C. (melting point of silver) bright cherry-red.
22nd hour-1050° C. (melting point of copper) very deep orange.
At this stage the samples are light grey, of chalky fracture, capable of receiving
scratches and rough to the tongue.
24th hour-1100° C. deep orange.
There is an external layer or zone lighter than the rest; the hardness is
increased; scratches may be produced; roughness to the tongue perceptible.
28th hour-1200° C. (melting point of gold at 90 per cent.) bright orange.
The exterior is reddish, the interior of a lighter hue; fracture not so chalky ;
will not receive scratches so readily; rough to the tongue.
30th hour-1250° C. (melting point of pure gold) very bright orange.
A dark spotted surface with grey violaceous stripes; interior dark; vitreous
appearance; splintery fracture; will receive no scratches; is not rough to the
tongue.
32nd hour-1300° C. (melting point of steel) nascent white.
The appearance is that of uniform micro-granulitic porphyry; the characteristics
of hardness go on increasing.

page_text: 34th hour 1400° C. brilliant white.
The material becomes still harder and more crystalline and may now be said to
have attained perfection.
This last temperature will prevail and even be exceeded if the furnace is charged
till the 36th hour. The furnaces are then closed, the orifices cemented and the
dampers of the chimney shut gradually.
This should on no account be done
suddenly as it would inevitably cause crevices and cracks in the furnace, owing to
the enormous heat stored up therein. Two hours after, all the orifices are closed,
and for 8 to 10 hours a kind of secondary baking takes places. Then the furnaces
begin to cool; but the cooling is not complete, or yet sufficient, for at least three
days; so that the whole operation lasts about 5 or 6 days.
Now I wish, in conclusion, to make two remarks concerning the influence of the
fire upon the goods made by this process.
(a) Until a temperature of 1200° C. (bright orange heat) is attained, the
action is the same as in the baking of bricks. The change in the material takes
place gradually and inwardly, the centre forming the least resistant zone. In point
of fact, I have, in experimenting on a large scale, raised the temperature of the
fire to 1100° C. only (deep orange) and having kept it at this height for about
48 hours, the blocks of pyrosilex I obtained from the furnaces or kilns, after cooling,
combined the characteristics and consistency of ordinary bricks of good quality.
Having on another occasion carried the fire to 1200° C. (bright orange) I obtained
goods equal in quality and consistence to the best Burgundy bricks made of
specially selected earths. But in either case nothing beyond the qualities of brick
could be obtained.
(b) By raising the temperature to 1400° C. (brilliant white),-far beyond the
melting point of tempered steel, it will be found upon the inspection and com-
parison of the gauges or test-glasses, which are removed in succession beginning
at 1250° C., that the crystal-developing forces act outwardly, beginning at the
core; so that the centre is visibly porphyrized, shiny and neither susceptible of
receiving scratches nor rough to the tongue, while the periphery has still the aspect
and consistency of brick; and on the samples a kind of glazing is perceptible on
the outer surface. Besides when the product has attained perfection i.e. become a
perfect imitation of real eruptive rock free from any deformation and showing
a shrinkage, which though variable is always less than 10%, it is no longer capable
of any modification under any temperature whatsoever.
The pyrosilex furnaces should be internally lined with the best fire-bricks which
will be subjected to no alteration, seeing that in my process neither salt nor any
flux is made use of. The furnaces should be provided with a reversed flame, pre-
ferably circular shaped and with an elliptically arched roof. The flame reversing-
wall should rise to about 25 or 30 centimetres from the arch, unless gas is employed
as fuel, in which case the flame may be allowed to act direct.
Dated this 2nd day of June 1892.
.
W. P. THOMPSON & BOULT,
Agents for the Applicant.
COMPLETE SPECIFICATION.
Improved Manufacture of Material suitable for Building and
Architectural Purposes, and for Ceramic and other similar Works.
I, MARC LAFFONT of 95 Boulevard Beaumarchais, Paris in the Republic of
France, M.D., 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:-
Very small residues of various species of eruptive rock have before now been
obtained in laboratories by melting either certain chemicals or the component
substances of the rock itself at a temperature which has never been less than

page_text: 1050° C.; this minimum temperature, indeed, applying to rock the component
parts of which are most fusible; but in most cases the temperature had to be raised
from 1300° to 1600° C. and upwards, while in no case have so quite fire-proof
materials been employed.
Now it is an unquestionable fact that eruptive rock might become a very superior
building material but for the difficulty of hewing it and its great hardness. I have
therefore endeavoured to reproduce this material artificially, on a large scale, and
in the final form in which it is ready for immediate use, and I intend to introduce
the new material under the name of "pyrosilex." I will now proceed to describe
its manufacture.
From an economical point of view, the manufacture of artificial eruptive rock
from chemicals, or from the dust of the rock itself, is evidently quite out of the
question, considering the great expense it would involve.
But chemistry, mineralogy, and the study of geological strata instruct us that
the different kinds of clay are neither more nor less than sedimentary or eruptive
rock, more often eruptive, modified and disintegrated through meteorological
influences. I have therefore selected clay as a component element of the artificial
eruptive rock.
Considering that the changes undergone by igneous rock through meteorological
influences result in the disappearance of its original properties while in the
incandescent condition it becomes consolidated, my first operation consists in baking
or calcining the clay at a high temperature. For this purpose I employ, not the
powdered clay known as fire-clay (which only consists of hydrated silicate of alumina
containing more or less moisture and a slight tincture of oxide of iron, or of
alkaline salts or carths) but what is known as fusible clay, containing larger quan-
tities of oxide of iron (from 3 to 10 per cent. and more) lime (from 3 to 10 per cent.
and more), magnesia, alkalies and sometimes a certain amount of maganese, in
other words I preferably use clay containing all those elements which constitute
eruptive rock. To prevent the clay subjected to the action of the fire, from
undergoing an undesirable alteration or deformation by melting, after it has been
calcined, when it is desired to give it a definite form with a view to immediate use)
I adopt the methods commonly in use in the pottery and tile manufacture.
In order to obtain material similar to eruptive rock, I therefore employ a
mixture of calcined fusible clay and of crude fire-clay; or a mixture of dust of
eruptive rock, of grit or sandstone, of clay-slate or ordinary slate, or of sand
resulting from the disintegration of rock, with crude fire-clay, in proportions
varying according to the nature and properties of the mixed substances. The
mixture is first made in a dry condition and then moistened and stirred; and this is
repeated as many times as is necessary to attain the desired degree of plasticity;
the plastic mass is then thoroughly dried and baked at a high temperature.
White heat should in all cases be attained, that is to say the temperature should
never be less than 1250° C. but may according to the degree of infusibility, be
much higher. At less than 1250° C. " pyrosilex can not be obtained by this
process.
"
(1.) INITIAL PHYSICAL CONDITION OF THE MATERIALS TO BE TREATED.
It is well known that the more finely a substance is divided the greater surface
it offers for the action of other substances with which it is combined or compounded.
It is therefore necessary that the substances to be treated by this process should
be dry, and in the condition of powder. After they have been mixed in the dry
state, they should be stirred 2 or 3 times over in suitable vats or tanks, so that
they are uniformly moistened and kneaded and may acquire the desired plasticity
and consistency. This pulpy mass is then for a space of time which may vary
according to circumstances, allowed to rest in a place where its degree of moisture
cannot vary. Moulding is next proceeded with, the mass when introduced into the
moulds being either hard or soft, the latter being preferable,

page_text: (2.) PRESSING.
The bricks, tiles, slabs, or the like are pressed after they have been moulded and
partly dried, though they must still be sufficiently plastic to slightly yield to the
pressure of the finger. The pressing is performed by means of any suitable kind
of press preferably hydraulic.
(3.) DESICCATION OF THE PRESSED ARTICLES PREVIOUS TO THEIR being
PLACED INTO THE KILN.
It is generally known that ceramic goods should be dried as thoroughly as
possible before being placed in the kiln, dessication being of the highest importance.
These are the general lines on which this process is carried out and I shall now
proceed to describe it in detail.
THE PROCESS.
(1) The fire-clay to be employed is first selected: It may be of any suitable
kind, provided it is dilutable, malleable, plastic, and as free as possible from foreign
bodies (such as alkalies, lime, magnesia, oxide of iron or the like). After being
dried this clay is reduced to powder and sifted. For convenience I shall hereinafter
refer to this powdered clay as the plastic substance.
(2) On the other hand any of the following materials may be chosen according
to local circumstances, facilities of conveyance, cost of production, etc. ; which
materials are also reduced to powder and sifted :
.
(a) Fragments of eruptive rock of various kinds such as protogyne, eurite,
retinite, perlite, obsidian, compact syenite, compact fine-grained porphyry,
diabase, serpentine, trap, melaphyre, dolerite, basalt etc.;
(b) Quartzy sandstone or sand;
(c) Clay-slate or ordinary slate ;
(d) Fusible, non-marlaceous clay previously calcined or baked (such as chips
or waste from brick-yards).
One of these materials, no matter which, is powdered and sifted; and in
referring to it hereinafter I propose calling it the fusible material.
(3) The plastic material and the fusible material are now mixed together in
proportions varying according to the nature of each which may be readily
ascertained by preparatory experiments (made, say in a muffle-furnace), the scale
of comparison being on the one hand, 1, 2, 3, 4, or 5 parts of plastic material, and
on the other hand, 5, 4, 3, 2, or 1 parts of fusible material.
(4) After thoroughly mixing the two materials, the mixture is moistened and
stirred so as to make it homogeneous and ensure uniform moisture throughout.
The stirring process is preferably interrupted several times, as intermittent stirring
will better develop the plasticity of the moisture. When stirred the mass should,
until it is required for use, be kept in a place where its degree of dampness can
undergo no alteration. At this stage the material shall herein after be referred to
as the mass.
(5) The mass may be differently employed, according to the purpose it is to fulfil
or the kind of goods it is desired to manufacture.
(a) For decorative (stamped, moulded, or turned) pieces, or for hollow articles
such as pipes, each article is made in one operation and then directly
conveyed into the drying chamber.
(b) In the case of solid blocks, such as bricks, paving-stones, slabs, etc., the
mass is first placed in moulds and introduced into the first drying-chamber,
where it is left until, under a strong pressure of the finger, it shows a slight
mark. It is then ready to go to the press, and upon being pressed, it is
taken to the second drying chamber.
A rough mixture in which homogeneity is disregarded, may yield a mass of

page_text: fact, I have, in experimenting on a large scale, raised the temperature of the fire
to 1100° C. only (deep orange) and having kept it at this height for about 48 hours,
the blocks of pyrosilex I obtained from the furnaces or kilns, after cooling,
combined the characteristics and consistency of ordinary bricks of good quality.
Having on another occasion carried the fire to 1200° C. (bright orange), I obtained
goods equal in quality and consistence to the best Burgundy bricks made of
specially selected earths. But in either case nothing beyond the qualities of brick
could be obtained.
(b) By raising the temperature to 1400° C. (brilliant white),-far beyond the
melting point of tempered steel,-it will be found upon the inspection and com-
parison of the gauges or test-glasses, which are removed in succession beginning
at 1250° C., that the crystal-developing forces act outwardly, beginning at the core;
so that the centre is visibly porphyrized, shiny and neither susceptible of receiving
scratches nor rough to the tongue, while the periphery has still the aspect and
consistency of brick; and on the samples a kind of glazing is perceptible on the
outer surface. Besides when the product has attained perfection i.e. become a
perfect imitation of real eruptive rock free from any deformation and showing a
shrinkage which though variable is always less than 10%, it is no longer capable
of any modification under any temperature whatsoever.
The pyrosilex furnaces should be internally lined with the best fire-bricks which
will be subjected to no alteration, seeing that in my process neither salt nor any
flux is made use of. The furnaces should be provided with a reversed flame,
preferably circular shaped and with an elliptically arched roof. The flame
reversing-wall should rise to about 25 or 30 centimetres from the arch, unless gas
is employed as fuel, in which case the flame may be allowed to act direct.
Having now particularly described and ascertained the nature of my said inven-
tion and in what manner the same is to be performed, I declare that what I
claim is :-
1. A material suitable for building and architectural purposes and for ceramic
and other similar works composed of crude fire proof clay dried crushed and sifted
with fragments of eruptive rock such as grit or sandstone clay-slate ordinary slate
sand or the like in their different geological metamorphoses also dried and crushed
sifted uniformly moistened placed in moulds and either pressed or not according
to the nature of the articles to be made and lastly dried and progressively raised
to a temperature higher than 1250° C. substantially as described.
2. A material suitable for building and architectural purposes and for ceramic
and other similar works composed of baked or burnt fusible clay and crude fire-
proof clay in mixtures such as are mentioned in the preceding claim such mixtures
being heated to a higher temperature than 1250° C. and thereby producing material
possessing all the properties of the finest eruptive rock and the fracture of which
has a splintery or shell-like crystalline or euritic appearance it being incapable of
absorbing moisture free from any roughness perceptible to the tongue proof against
the action of acids polishable either by means of its own dust or by emery and hard.
3. The employment in the treatment of certain non-fusible kinds of clay of
mixtures of crude clay and of a suitable cement. made of the same clay for the
purpose specified.
4. The employment of mixtures of a number of substances such as are herein-
before referred to for the purpose of obtaining a material of various shades or
colours in stains, veins zones and the like substantially as described.
5. The treatment of the mixtures as aforesaid by the process of operation herein-
above set forth for the purpose of obtaining articles of various shapes or forms by
moulding stamping cutting or the like.
3000