IMPROVEMENTS IN THE MANUFACTURE OF MARBLE
Year: 1884

page_text: I AUGUSTO GUATTARI of 91 Shirland Gardens, Paddington, in the County of
Middlesex, Engineer, do hereby declare the nature of the said invention for
IMPROVEMENTS IN THE MANUFACTURE OF MARBLE".to be as follows:-
This Invention relates to the manufacture of marble from sulphate of lime or
gypsum.
The process of manufacture differs according as the gypsum is left in its natural
state, or modified as to certain of its physical characteristics. By the first inethod
of treatment the marble is made from sulphate of lime (gypsum) without
decomposing the material which retains its natural structure grain & and is
transformed into veritable marble of which it acquires the weight consistency
colour appearance and polish.
By a simple modification of this same process artificial marble is made from
sulphate of lime or gypsum which is reduced to powder from which by special
manipulations and certain chemical preparations a marble is obtained possessing
the hardness durability, appearance, polish, colour and veining of antique marble.
Before entering into the details of the process it is desirable to enumerate the
different varieties of gypsum (sulphate of lime) which it is proposed to transform
into carbonate of lime (marble).
και
First variety..
(a) Gypsum spar or foliated gypsum comprehends,
1 Sparry gypsum.
2nd Foliated sulphate of lime.
3rd Selenite.
This variety under its different aspects is often translucent and almost colourless
when crystalized, but it frequently inclines to brown, grey, yellow, pink carmine,
red, and it contains 22% of water of hydration.

page_text: approaching to red, carmine, and violet. All the rocks of this class have about
4. 27% of water more or less.
(d) Fourth variety.
Mealy gypsum or pulverulent selenitic sulphate of lime, sulphite of lime and
sometimes fossil-farina. This substance though gypseous in reality is only a true
mealy lime; it is of a pure white inclining sometimes towards grey; it contains a
certain quantity of water of crystallization.
They have not therefore many characteristics common to the other kinds such
for example as gypsum of the fibrous the saccharoid the compact and the crystallized
varieties which have 20% of water.
These hydrated species of gypsum are met with in abundance in the lower
tertiary strata both in Italy and in France, and in England, Germany, Belgium,
and other places. They are as well as the other varieties mentioned above, more or
less susceptible of being hardened provided the water which they retain is taken out
by submitting them to the degree of heat required by each quality. This operation
is of very great importance as, if an error were committed in doing it the material
would be damaged so much that no profit could be gained from it. The dehydration
is then so important that it deserves to be studied with deep attention as the
success of this operation depends on the preparation of the gypsum in the ovens.
One and the same method of dehydration is not applicable to all the various kinds
of gypsum. It is intended to use all the above mentioned species of gypsum which
are found everywhere and to transform them into marble, following the rules of
dehydration and hydration by means of chemical compounds which will be
mentioned later.
The first operation is the dehydration of the gypsum which is effected in suitably
constructed stoves, care being taken to observe the following directions as to the
heat required for the dehydration of each variety of gypsum.
The first variety, that is the gypseous spar and its various analogues which
contain 22 per cent of water ought to be submitted the first time to a temperature
of 80° R; the gypsum is then sent into a prepared bath hereafter referred to, and
after having remained there the necessary time and been dried in the open air, it is
carried again to the oven where it is submitted to a temperature of 180° R in order
to complete its desiccation after which it is placed again in the bath and kept
there; it is dried in the air and it is then submitted to the final treatment.
For the second variety the same process is, necessary regarding the bath ; the
material is submitted to a temperature of 40° R the first time and of 150° R the
Becond time.
For the third variety with all its various types the operation is the same but
applying the first time a heat of 120° R, and the second time 190° R.

page_text: For the fourth variety nouning is changed as regards the bath; the temperature
to which the material is submitted is 80° R the first time and 133° R the second
time.
For the other varieties of gypsum, that is to say, the fibrous, the saccharoid, the
compact, the crystallised and the calciferous, the operation is the same as above
described as regards the baths but the material must be exposed the first time to
115° R and the second time to 195° R.
I will now proceed to describe the treatment to be applied to the rock which has
been dehydrated in order to harden it.
Before however entering into the description of the chemical processes, & slight
digression may be made. After many experiments it has been discovered that on
account of the great affinity of silica for lime the acid of silicate of potash would
combine directly with lime by decomposing the sulphate of lime (gypsum) and
transferring the sulphuric acid which had been combined with the lime to form a
sulphate of potash whilst the silicic acid combines with the lime. In obtaining this
experience it was ascertained that by wetting a piece of anhydrous sulphate of
lime of whatever form or color with a solution of silicate after exposure to the air,
it would acquire such a solidity that it could be compared as regards molecular
cohesion with every kind of marble and might receive such a polish as to deceive
the most experienced artist, and for gypsum of the first kind, that is to say, the
foliated spars, &c, &c, I use silicate of soda, hydrated silicate of lime composed of
a solution of other silicates in salts of lime.
For gypsum of the second kind, that is to say, the lithoid, the compact, &c, &c,
I use the silicate of lime, chloride of lime mixed with sulphate of potash, an
important process for the crystallization of gypsums which are not crystallizable,
acid phosphate of lime and also the sulpho silicate of potash or soda.
For gypsums of the third class the anhydrites, the muriacites, &c, I use the
sulpho silicate of potash, acid fluo silicate of potash, the double silicate of potash
and manganese, the hydro fluo borate of potash in which boric acid predominates.
For gypsum of the fourth kind, that is, the mealy gypsum, pulverulent sulphate
of lime, &c, &c, I use silicate of soda, bydrated silicate of lime, and all the salts of
lime.
For the other varieties enumerated, that is, the fibrous gypsum, the saccharoid,
the compact, the crystallised and the calciferous, I use chloride of sodium, borate of
soda or borax, biphosphate of soda or potash, sulphate of barytes mixed with a
solution of alkaline silicate; these substances are appropriated according to the
nature of the mineral rock to be operated on and according to the natural color
of the gypsum or those to be given to it artificially..
Application of the Bath Silicate of Potash -100 parts. of water are mixed with
61/2 parts of silicate of potash. The bath being thus prepared, the objects already
sculptured are plunged into it for the length of time necessary, to produce the first
hardening of the material and after having undergone the second dehydration the
immersion is repeated in a bath saturated with sulpho silicate of potash in suitable
proportions; in the same way silicate of soda and all the other silicates could be
employed.
Silicate of lime is not applicable where the rock is to be colored artificially, but
it produces a great degree of hardness and it is available for hardening the white
rock and also naturally colored rock.
Regarding the other chemical substances mentioned in the application of the
process, the solutions indicated in the processes already explained will be used
regarding the variety and nature of the gypsum to be used, it is useless to describe
these things here which are part of practice which it is indispensible to possess in
order to obtain the desired effect.
Description of the way to manufacture the colours for marbles made by the first
and second methods (the soluble colors are to be applied by imbiboing for the
first method, the oxides for the artificial marbles).

page_text: Manufacture of artificial marble from powdered gypsum denominated marmorite
in order to convert gypsum into artificial marble having the durability of stone
and resisting the action of the atmosphere the following process is used.
1. The sulphate of lime already reduced to small pieces and having been
de-hydrated by means of a heat of 133° more or less, according to the quality
of the rock employed is placed in a bath, saturated with one of the chemical
substances already mentioned until it is thoroughly impregnated; that done it is
withdrawn and carried to the stoves and there dried and where once dried it
is taken to be burnt, submitting it to a very high temperature or a red heat.
After a second burning and cooling, the products are submitted to the action
of edge runners where they are reduced to powder which is passed through a
sieve.
This powder thus prepared becomes "marmorite" with which are manufactured
objects of all desired forms by means of dies stamps &° &°.
This "marmorite" kept perfectly dry is treated in the following manner:
The necessary quantity is put into a trough in which is poured silicated or
saturated water remaining from the first baths and kneaded into a paste which
is put in the moulds; it is then submitted to the action of presses; after leaving
the press the moulded article is taken out in order to dry it again in the open air.
It is also to be noted that the material will acquire more durability the longer it is
exposed in the air before being worked.
The colours which are formed with mineral powders and liquids are mixed with
the paste. All the above mentioned operations being finished the treatment is
completed by washing and polishing.
According to another mode of making artificial marble from marmorite, the
crude gypsum is pulverised and mixed with the waste rock formed by the consecu-
tive operations of the first method of manufacturing marble. There is afterwards
added to this powder 4% of its weight of sulphate of aluminum or aluminate of
potash and this mixture is calcined and then pulverized again. The powder thus

page_text: prepared is put into a bath composed of a saturated solution of chloride of sodium
or of silicate of alumina in the proportion of one part to 12 of water. Then it is
mixed into a paste according to the same rules and with the same precautions as in
the previous method.
Although the two systems which have just been described give good results,
there is another which although differing little in substance from the preceding
is more advantageous for the workmen permitting them to work calmly and with
precision, as the marmorite sets much more slowly than in the two preceding
methods; this result is obtained by mixing with 100 parts of "marmorite
4 parts of the root of the marsh mallow, and adding 40 parts of water. The paste
thus prepared procures not only the advantages mentioned above, but it gives a
very beautiful aspect and the greatest brilliancy to the objects made from it owing
to the amount of mucilage which the marsh mallow contains.
This system facilitates the working of pieces of great thickness which are
hardened like stone and which can be easily turned and worked with iron tools
like marble.

page_text: ""
"
I AUGUSTO GUATTARI of 91 Shirland Gardens, Paddington in the County of
Middlesex, Engineer, do hereby declare the nature of the said invention for
IMPROVEMENTS IN THE MANUFACTURE OF MARBLE and in what manner the
same is to be performed, to be particularly described and ascertained in and by the
following statement :-
This Invention relates to the manufacture of marble from sulphate of lime or
gypsum.
The process of manufacture differs according as the gypsum is left in its natural
state or modified as to certain of its physical characteristica. By the first method
of treatment, the marble is made from sulphate of lime (gypsum) without decom-
posing the material, which retains its natural structure grain &c and is transformed
into veritable marble of which it acquires the weight, consistency, colour, appearance
and polish.
By a simple modification of this same process what I may term artificial marble
(in contradistinction to marble produced by the first method) is made from sulphate
of lime or gypsum which is reduced to powder from which by special manipulations
and certain chemical preparations a marble may be obtained possessing the hardness
durability, appearance, polish, colour and veining of antique marble.
Before entering into the details of the process it is desirable to enumerate the
different varieties of gypsum (sulphate of lime) which it is proposed to transform
into carbonate of lime (marble).
Lithoidal gypsum and also compact gypsum compact massive and stony sulphate
of lime and often alabaster. This kind of stony gypsum is found principally of a
greyish white color and sometimes colored otherwise; it is often translucent and
always amorphous, and it is scarcely ever found sparry and foliated. Analysis
shows this variety and its sub-divisions to possess 38% of water of hydration.
(c) Third variety.
3
Anhydrite, muriacite, and anhydrous sulphate of lime, and sometimes ferigite,
vulpinite, bardiglione, bardiglio, and gypsum of bergamo. This kind of gypsum
which is always deficient in water of crystallization, comprehends several distinct
sub-varieties of sulphate of lime which are 1° Sparry anhydrite, 2° Sparry 4
anhydrous gypsum, 3° Sulphate of lime, the colour of which is very often milky
white sometimes inclining more or less to gray, azure and reddish, and much
more rarely approaching to red, carmine, and violet. All the rocks of this class
have about 4. 27% of water more or less.

page_text: (d) Fourth variety.
Mealy gypsum or pulverulent selenitic sulphate of lime, sulphite of lime and
sometimes fossil-farina. This substance though gypseous in reality is only a true
mealy lime; it is of a pure white inclining sometimes towards grey; it contains a
certain quantity of water of crystallization.
They have not therefore many characteristics common to the other kinds such
for example as gypsum of the fibrous the saccharoid the compact and the crystal-
lized varieties which have 20% of water.
These hydrated species of gypsum are met with in abundance in the lower
tertiary strata both in Italy and in France, and in England, Germany, Belgium, and
other places. They are as well as the other varieties mentioned above, more or
less susceptible of being hardened provided the water which they retain is taken
out by submitting them to the degree of heat required by each quality. This
operation is of very great importance since, if an error were committed in
performing it the material would be damaged so much that no profit could be
gained from it. The dehydration is therefore so important that it deserves to be
studied with deep attention as the success of this process depends on the prepara-
tion of the gypsum in the ovens; One and the same method of dehydration is not
applicable to all the various kinds of gypsum. It is intended to use all the above
mentioned species of gypsum which are found everywhere and to transform them
into marble, following the rules of dehydration and hydration by means of chemical
compounds which will be mentioned later on.
1⚫t method.
The first operation is the dehydration of the gypsum which is effected in suitably
constructed stoves, care being taken to observe the following directions as to the
heat required for the dehydration of each variety of gypsum.
The first variety, that is the gypseous spar and its various analogues which
contain 22 per cent of water ought to be submitted the first time to a temperature
of 80° R; the gypsum is then immersed in a prepared bath hereafter referred to,
and after having remained there the necessary time and been dried in the open air,
it is carried again to the oven where it is submitted to a temperature of 180° R in
order to complete its desiccation after which it is placed again in the bath and kept
there; it is dried in the air and it is then submitted to the final treatment.
For the second variety the same process is necessary regarding the bath; the
material is submitted to a temperature of 40° R the first time and of 150° R the
second time.
For the third variety with all its various types the operation is the same but
applying the first time a heat of 120° R, and the second time 190° R.
For the fourth variety nothing is changed as regards the bath; the temperature
to which the material is submitted is 80° R the first time and 133° R the second
time.
For the other varieties of gypsum, that is to say, the fibrous, the saccharoid, the
compact, the crystallised and the calciferous, the operation is the same as above
described as regards the baths but the material must be exposed the first time to
115° R and the second time to 195° R.
I will now proceed to describe the treatment, to be applied to the rock which
has been dehydrated, in order to harden it.
Before however entering into the description of the chemical processes, a slight
digression may be made. After many experiments it has been discovered that on
account of the great affinity of silica for lime the acid of silicate of potash would
combine directly with lime by decomposing the sulphate of lime (gypsum) and
transferring the sulphuric acid which had been combined with the lime to form a
sulphate of potash whilst the silicic acid combines with the lime. In obtaining
this experience it was ascertained that by wetting a piece of anhydrous sulphate
of lime of whatever form or colour with a solution of silicate after exposure to

page_text: the air, it would acquire such a solidity that it could be compared as regards
molecular cohesion with every. kind of marble and might receive such a polish
as to deceive the most experienced artist.
For gypsum of the first kind, that is to say, the foliated spars, &c, &c, I use
silicate of soda, hydrated silicate of lime composed of a solution of other silicates
in salts of lime.
For gypsum of the second kind, that is to say, the lithoid, the compact, &c, &c,
I use the silicate of lime, chloride of lime mixed with sulphate of potash, an
important process for the crystallization of gypsums which are not crystallizable,
acid phosphate of lime and also the sulpho silicate of potash or soda.
For gypsums of the third class the anhydrites, the muriacites, &c, I use the
sulpho silicate of potash, acid fluo silicate of potash, the double silicate of potash
and manganese, the hydro fluo borate of potash in which boric acid predominates.
For gypsum of the fourth kind, that is, the mealy gypsum, pulverulent sulphate
of lime, &c, &c, I use silicate of soda, hydrated silicate of lime, and all the salts of
lime.
'
For the other varieties enumerated, that is, the fibrous gypsum, the saccharoid,
the compact, the crystallised and the calciferous, I use chloride of sodium, borate of
soda or borax, biphosphate of soda or potash, sulphate of barytes mixed with a
solution of alkaline silicate; these substances are appropriated according to the
nature of the mineral rock to be operated on and according to the natural color of
gypsun or those to be given to it artificially.
the
Application of the Bath (Silicate of Potash)-100 parts. of water are mixed with
61, parts of silicate of potash. The bath being thus prepared, the objects already
sculptured are plunged into it for the length of time necessary to produce the first
bardening of the material and after having undergone the second dehydration the
immersion is repeated in a bath saturated with sulpho silicate of potash in suitable
proportions; in the same way silicate of soda and all the other silicates could be
employed.
Silicate of lime is not applicable where the rock is to be colored artificially, but it
produces a great degree of hardness and it is available for hardening the white rock
and also naturally colored rock.
Regarding the other chemical substances mentioned in the application of the
process, the solutions indicated in the processes already explained will be used
regarding the variety and nature of the gypsum to be used; it is useless to
describe these things here which are part of practice which it is indispensible
to possess in order to obtain the desired effect.
Description of the way to manufacture the colours for marbles made by the first
and second methods (the soluble colors are to be applied by imbibing for the first
method, the oxides for the artificial marbles).
1. Black is obtained by pyrolignite of iron reduced by boiling in gallic acid with
sirico black and other substances.
2. Yellow and its tints are obtained
(a) with citrate of iron dissolved in oxysulphate of iron.
(b) with sulphate of cadmium.
(c) with chromate of yttrium.
(d) with chromate of lithium.
(e) with crocoxantina.
(f) with yellow of antimony.
3. Red and its tints to rose are obtained
with dragons blood dissolved according to rule.
(b) with madder root of scarlet colour prepared according to rule.
(c) with sesquioxide of Iron.
(d) with Mussaride red.
(c) with sulphate of didymium and the salts derived from it which are
soluble in water and give a rose colour.

page_text: 4. Azure blue is obtained with sulphate of sodium mixed with acetate of copper
and tartaric acid in equal weights which are boiled, till the colour is obtained, with
oxide of cobalt, with oxide of copper and indigo dissolved in water.
5. Green and its tints with verdigris dissolved according to rule and mixed hot
with wax; with hydrochlorate of cobalt with the soluble oxide of chromium with
silicate of copper. From the combination of the principal colours mentioned are
obtained the other colours desired.
Manufacture of artificial marble from powdered gypsum denominated marmorite.
In order to convert gypsum into artificial marble having the durability of stone and
resisting the action of the atmosphere the following process is used.
1. The sulphate of lime already reduced to small pieces and having been
de-hydrated by means of a heat of 133° R more or less, according to the quality of
the rock employed is placed in a bath, saturated with one of the chemical substances
already mentioned until it is thoroughly impregnated; that done it is withdrawn
and carried to the stoves and there dried and when once dried it is taken to
be burnt, submitting it to a very high temperature or a red heat. After a second
burning and cooling, the products are submitted to the action of edge runners where
they are reduced to powder which is passed through a sieve.
This powder thus prepared becomes "marmorite" with which are manufactured:
objects of all desired forms by means of die stamps &° &°
This "marmorite" kept perfectly dry is treated in the following manner:
The necessary quantity is put into a trough in which is poured silicated or
saturated water remaining from the first baths and kneaded into a paste which is
put in the moulds; it is then submitted to the action of presses; after leaving the
press the moulded article is taken out in order to dry it again in the open air. It
is also to be noted that the material will acquire more durability the longer it is
exposed in the air before being worked.
The colours, which are formed with mineral powders and liquids are mixed with
the paste. All the above mentioned operations being finished the treatment is
completed by washing and polishing.
According to another mode of making artificial marble from marmorite, the
crude gypsum is pulverised and mixed with the waste rock formed by the
consecutive operations of the first method of manufacturing marble. There is
afterwards added to this powder 4% of its weight of sulphate of aluminum or
aluminate of potash and this mixture is calcined and then pulverized again. The
powder thus prepared is put into a bath composed of a saturated solution of
chloride of sodium or of silicate of alumina in the proportion of one part to 12 of
water. Then it is mixed into a paste according to the same rules and with the same
precautions as in the previous method.
Although the two systems which have just been described give good results,
there is another which although differing little in substance from the preceding is
more advantageous for the workmen permitting them to work calmly and with
precision, as the marmorite sets much more slowly than in the two preceding
methods; this result is obtained by mixing with 100 parts of "marmorite" 4 parts
of the root of the marsh mallow, and adding 40 parts of water. The paste thus
prepared procures not only the advantages mentioned above, but it gives a very
beautiful aspect and the greatest brilliancy to the objects made from it owing to
the amount of mucilage which the marsh mallow contains.
This system facilitates the working of pieces of great thickness which are
hardened like stone and which can be easily turned and worked with iron tools like
marble.

page_text: Having now particularly described and ascertained the nature of the said
Invention and in what manner the same is to be performed I declare that what
I claim is:
1st The herein described process of manufacturing marble from gypsum
(sulphate of lime) which consists in dehydrating the material and submitting
the same to the action of baths or solutions of the chemical agents mentioned,
substantially as specified.
2nd The herein described process of manufacturing marble from gypsum
(sulphate of lime) which consists in submitting the material to the following
consecutive operations viz (a) dehydration; (b) immersion in a bath or solution of
the chemical agents mentioned (c) second dehydration after drying in the open air
(e) second immersion in a bath or solution of the chemical agents mentioned, and,
lastly, desiccation of the material in the open air, the whole substantially as herein
specified.
3rd The manufacture of the material herein denominated "marmorite" by
dehydrating the powdered gypsum, then submitting it to the action of a bath or
solution of the chemical agents mentioned, then burning the material at a high
temperature, and subsequently grinding and drying the same, substantially as
specified.
4th The manufacture of artificial marble from the material herein denominated
"marmorite " produced as herein described and specified in the preceding claim, by
making the said material into a paste with the solution specified, then moulding
and drying, substantially as described.
5th The manufacture of the material herein denominated "marmorite" by
mixing with the pulverized crude gypsum, the waste chippings of the marble made
by the first method, adding a suitable proportion of sulphate of aluminum, or
aluminate of potash, then calcining, pulverizing, and afterwards immersing in a
bath of chloride of sodium or of silicate of alumina, as specified.
6th The manufacture of artificial marble from the "marmorite" produced as
specified in the last preceding claim by making the said material into paste
with the silicated or other solution specified, and then moulding and drying,
as described.
7th In the manufacture of artificial marble from the "marmorite" produced as
herein described, the addition thereto of a suitable proportion of marsh mallow as
specified.
8th In the manufacture of artificial marble from rock or powdered gypsum by
the processes herein described, the method of coloring the product by the use of
the materials, substantially as specified.