IMPROVEMENTS IN THE PRODUCTION OF ARTIFICIAL STONE OR MARBLE AND IN COLORING " THE SAME
Year: 1882

page_text: LETTERS PATENT to John Henry Johnson of 47 Lincolns Inn Fields in
:
the County of Middlesex Gentleman for an Invention of "IMPROVEMENTS
IN THE PRODUCTION OF ARTIFICIAL STONE OR MARBLE AND IN COLORING
"
THE SAME A communication to him from abroad by the Certaldo Marble
Company Limited of Paris in the Republic of France.
PROVISIONAL SPECIFICATION left by the said John Henry Johnson at the
Office of the Commissioners of Patents on the 18th August 1882.
JOHN HENRY JOHNSON of 47 Lincolns Inn Fields in the County of Middlesex
Gentleman " IMPROVEMENTS IN THE PRODUCTION OF ARTIFICIAL STONE OR
MARBLE AND IN. COLORING THE SAME". A. communication to me from abroad by
the Certaldo Marble Company Limited of Paris in the Republic of France
This Invention relates to the production of Artificial stone or marble and in
coloring the same and consists firstly in subjecting solid natural Sulphate of Lime
to a gradual process of gradual partial or completo dehydration throughout the
mass and then to a gradual process of impregnation or to repeated limited
immersions in one or more of the solutions hereafter referred to in order gradually
to effect the hardening and coloring of the material.
The said material is taken in the solid natural state without pulverization and
cut or carved or similarly worked in to the required block slab or other form or
article.
In carrying out this Invention I firstly submit the solid natural sulphate of
lime to a process of partial or complete dehydration at a temperature ranging from
about 200° F to about 400° F, the same being gradually attained.
In carrying out this process of gradual and of partial or complete dehydration I
submit the solid native sulphate of lime gradually to the action of heat until such
desired partial or complete dehydration is obtained, such result being gradually
obtained and effected at a gradually increasing temperature varying from about
200° F to about 400° F. But by preference I employ a temperature varying from
260° F to 300° F the same being gradually attained.

page_text: When such gradual partial or complete dehydration has been effected throughout
the mass,
I then either allow the stove or furnace gradually to cool down in order
that the contents may become gradually cooled or I remove the block slab or
article from the stove and allow the same to undergo a gradual cooling process and
I then submit it to the hardening process causing it to be subjected to the gradual 5
action of solutions such for example as those of alum and of oxalic acid such
solutions being employed either alone or in conjunction with coloring matters or
agents such as minerals or organic compounds.
The length of time during which the material should be kept under this
hardening treatment will depend somewhat on the strength of the ingredients 1
composing the bath the character and rapidity of the chemical reactions involved
the porosity and nature or physical and chemical condition of the material but
usually about twelve hours more or less will suffice though I prefer repeated dippings
two, three or more, (say two or three) seconds at first and increasing gradually to
one, two, three or more minutes, more or less, with drying intervals of like increasing
length between dippings, for half or three quarters of an hour or so, after which the
article may remain in the bath for twelve hours or so. Or instead of employing
solutions of alum and of oxalic acid for effecting the hardening process, I employ,
for example, a solution of carbonate of soda or carbonate of potash or I employ the
soluble compounds of magnesia, such for example, as sulphate of magnesia or I
employ solutions of metallic compounds or Salts, such as Sulphate of Iron, Sulphate
of Zinc or sulphate of copper or mixtures of the same or instead of employing
inetallic salts or compounds, I employ soluble compounds of potash, such for example,
as prussiate of potash or bichromate of potash or cyanide of potassium either alone
or in conjunction with coloring matters, such for example, as aniline colors or with
vegetable coloring matters such for example as Indigo logwood Brazil wood and
yellow wood or with animal or mineral coloring matters such as Sepia or
Cochineal.
The following are examples of baths which have been found to answer well:
For the making of a white "certaldite" the bath consists (by weight) of water,
200 parts, alum 4 parts and oxalic acid 2 parts.
For the making of black certaldite or one practically so, or of a dark color.
The bath consists of water by weight
Campeachy wood (Logwood)
Gall nuts
Sulphate of iron
Do. of copper
200 parts
3.50
"
6
"
"
0.50
"
For the production of Certaldite of Rose or pink color or tinge.
In this case the bath is prepared by taking 200 parts by weight of the bath
described for the bath for white certaldite and there is dissolved therein a small
per centage of say from the 100 to the 200 parts of one per Cent by weight of
rose of aniline or rose of naphthaline varying the amount according to the shade
desired.
The following composition is for the preparation of a bath for making ivory
colored certaldite For this purpose there is used of the white bath by weight
200 parts of Brazil wood one part sulphuric acid 1 part rose of aniline from 1000th
to 5000th of one part.
For the production of red certaldite To this end there is used by weight of
water 200 parts alum 4 parts oxalic acid, part Brazil wood 6 parts, chloride of
zine one part (as a mordant) cream tartar / 10th of one part.
For making pale yellow colored certaldite there are used two baths in which
the gypsum is dipped alternately several times
The first consists of the white bath by weight 200 parts and of sulphate of
copper six parts after the gypsum has been dehydrated and dipped in this bath as
herein before described it is dipped into a bath composed of the white bath by
weight 200 parts with cyanide of potassium 6 parts and thereafter again into, the

page_text: first bath then again into the second bath and so on increasing the duration of
dippings and drying intervals.
In this
For the making of certaldite having yellow spots on the back ground or body of
a general red tint-To this end there is added to the bath described for red
certaldite about ½ part by weight of sulphuric acid This color can only be
obtained in a particular quality of gypsum containing impurities of baric nature
which tend to neutralize the sulphuric acid disposed in a certain patchy way.
For the preparation of the bath for the making of yellow certaldite
case there are used two baths, the first is prepared by water by weight 200 parts and
sulphate of iron six parts and the second of the white bath by weight 200 parts and
Bichromate of potash two parts. The material is treated in each of these baths
alternately substantially in the manner hereinbefore described with reference to the
pale yellow bath After the dippings the pieces are left to soak in the sulphate of
iron bath,
The following bath is for the making of a yellow certaldite-In preparing it
there is used of the white bath by weight 200 parts and logwood by weight
4 to 6 parts.
For making green certaldite there is used water 200 parts alum 3 to 4 parts,
logwood 2 to 3 parts and sulphate of indigo 1 to 2 parts.
A bath for the making of dark green certaldite consists of water 200 parts
alum 2 parts, logwood 4 parts and sulphate of iron 2 to 3 parts-The use of
sulphate of iron enables the proportion of alum to be reduced from that first
described as the sulphate of iron aids in hardening and also combines with the
logwood to make color.
A bath for making a lilac colored certaldite is composed of the white bath
hereinbefore described 200 parts Campeachy wood 8 parts and to this is added a
little carbonate of soda as much as may be necessary to neutralize the excess of
acid in the white bath Other alkaline matter may be used for this purpose The
hardening is done by the white bath and the compeachy wood gives colour.
important to neutralise the excess of acid in order to prevent the making of a
reddish tint.
It is
For the preparation of a bath for the making of a sky blue certaldite there is
used of the white bath 200 parts alum 6 parts (in all 10 parts of alum) cyanide of
potassium from 1/15000th to 1/30000th.
For making dark blue certaldite there is used of the white bath, 200 parts by
weight aniline blue 1 part and sulphuric acid 1/2 part. The sulphuric acid acts as a
solvent on the aniline.
The blue which I prefer to use is in Europe distinguished by the letters B BB
For making a certaldite of a light green colour there is used water 200 parts,
sulphate of copper 16 parts, ammonia 20 parts. The sulphate of copper takes the
place of the alum for hardening and a portion of it also unites with the ammonia
so as to make the desired coloring matter
For the preparation of a bath for the making of white certaldite there is used
water 100 parts, sulphate of iron 1 part This bath is used with the lighter colored
gypsum or in those gypsums wherein little or no change of color is desired In
distinguishing the colours in all the foregoing cases I mean the colours to be given to
the main body or sulphate of lime part of the gypsum The colors or tints of the
impurities present in the gypsum will generally be of a dark shade and will vary
considerably with the kind of impurity and the effect thereon of the ingredients
composing the bath.
The material when thoroughly dry and after being treated in one or some of the
methods hereinbefore described is scraped planed or polished or otherwise brought
to the necessary surface and then coated or treated with oil paraffin stearine wax
or other preservative.

page_text: SPECIFICATION in pursuance of the conditions of the Letters Patent filed
by the said John Henry Johnson in the Great Seal Patent Office on the
17th February 1883.
JOHN HENRY JOHNSON of 47 Lincolns Inn Fields in the County of Middlesex
Gentleman " IMPROVEMENTS IN THE PRODUCTION OF ARTIFICIAL STONE OR
MARBLE AND IN COLOURING THE SAME a communication to me from abroad by
The Certaldo Marble Company Limited of Paris in the Republic of France
دو
This Invention relates to the production of artificial stone or marble and to
colouring the same and consists firstly in subjecting solid natural sulphate of lime
or natural minerals containing sulphate of lime as their basis to a (preferably very
gradual) process of partial or complete dehydration throughout the mass then
to a (preferably very gradual) process of impregnation or to repeated immersions
of increasing duration in one or more of the solutions hereafter described in order
gradually to effect the hardening and colouring of the material.
The said material is taken in the solid natural state without pulverization
and cut or carved or similarly worked into the required block slab or other form or
article.
In carrying out this Invention the solid natural sulphate of lime is first
submitted to a process of partial or complete dehydration at a temperature ranging
from about 230 degrees Fahrenheit to about 320 degrees Fahrenheit the same being
preferably very gradually attained.
In carrying out this process of gradual and of partial or complete dehydration
the said native sulphate of lime is submitted gradually to the action of heat
until such desired partial or complete dehydration is obtained such result being
gradually obtained and effected at a gradually increasing temperature varying
from about 230 degrees Fahrenheit to about 320 degrees Fahrenheit―These
temperatures should be obtained by a very gradual increase from the ordinary
temperature extending over at least four hours before the highest temperature is
reached In ordinary cases an additional twelve hours submission to the attained
temperature will be found sufficient for slabs or objects one and a half to two
centimetres in thickness-The duration of the dehydrating process must be
proportioned to the thickness of the articles under treatment-For very thick
articles a period of as much as forty eight hours or even more will be found
necessary I find that different qualities of native sulphate of lime require different
temperatures to dehydrate them satisfactorily-These different temperatures
however all lie between the extremes of 230 degrees Fahrenheit and 320 degrees
Fahrenheit To ascertain if a suitable dehydration to the centre of the pieces bas
been attained it is desirable to put test pieces or blocks (of the same thickness as
that of the articles being treated) into the oven and to remove and break them
from time to time when the depth to which the dehydration has gone is at once
seen by the change of colour When such gradual partial or complete dehydration
has been effected throughout the material I then either allow the stove or furnace
gradually to cool down in order that the contents may become gradually cooled or
I remove the block slab or article from the stove and allow the same to undergo a
gradual cooling process extending over at least six hours for large pieces and
continued in all cases until the temperature of the whole piece is reduced to or
about that of the bath or baths into which it is then to be dipped as hereinafter
described I then submit it to the hardening process causing it to be subjected to
the gradual action of hardening or indurating solutions such for example as
solutions of alum and oxalic acid such solutions being employed either alone or in
conjunction with colouring matters or agents either mineral or organic

page_text: The length of time during which the material should be kept under this
hardening treatment will depend somewhat on the strength of the ingredients
composing the bath, the character and rapidity of the chemical reactions involved,
and the porosity and nature or physical and chemical condition of the material, but
usually about twelve hours more or less will suffice But the immersion should be
preceded by repeated dippings (alternating with drying intervals) six seven or
more These dippings should be of very short duration (say from three to ten
seconds each) and it is very important that they should be continued until the
surface of the piece remains wet for at least three minutes after its withdrawal
from the bath The preliminary dipping and drying intervals may if desired be of
gradually increasing duration After this the pieces must be immersed continuously
in the indurating bath for twelve hours or instead of employing solutions of alum
for effecting the hardening process there may be employed for example a solution
of carbonate of soda or carbonate of potash or the soluble compounds of magnesia
such for example as sulphate of magnesia are employed or solutions of metallic
compounds or salts such as Sulphate of Iron Sulphate of zinc or Sulphate of Copper
or mixtures of the same may be employed or instead of employing metallic Salts or
compounds soluble compounds of potash such for example as prussiate of potash or
bichromate of potash or cyanide of potassium may be employed either alone or in
conjunction with colouring matters such for example as aniline colours or with
vegetable colouring matters such for example as Indigo, Logwood Brazil Wood and
Yellow Wood or with animal or mineral colouring matters such as Sepia or
Cochineal-If an extreme degree of hardness be required the processes of
dehydrating and indurating as hereinbefore described may be repeated once
or even oftener.
The following are examples of baths which have been found to answer well.
For the making of a white "Certaldite" the bath may consist (by weight) of
Water 200 parts Alum 4 parts and Oxalic Acid 2 parts.
For the making of black Certaldite or one practically so or of a dark colour the
bath consists of
Solid Extract of Yellow Wood (Fustic)
Powdered Gall Nuts
Sulphate of Iron
Sulphate of Copper
0.50
"
"
"
"
3
"
"
0.50
"
"
For the production of Certaldite of a rich brown color or tinge-The bath is
prepared by taking 200 parts by weight of water 4 parts by weight of Alum two
parts by weight of oxalic acid and a sufficient quantity of extract of husks and
shells of walnuts to produce the desired depth of colour which must be ascertained
by trial pieces
The following composition is for the preparation of a bath for making ivory
coloured Certaldite For this purpose there are used of the white bath (by weight)
200 parts; of solid Extract of Brazil Wood One part; Sulphuric Acid half part;
Rose of Aniline from 1000th to 5000 th of 1 part The purest descriptions of gypsum
should be selected for making this ivory coloured Certaldito.
For the production of red Certaldite there are used (by weight) of water
200 parts; Alum 4 parts; Oxalic Acid half part; Solid Extract of Brazil Wood or
Lima Wood 6 parts; Chloride of Tin 2 parts (as a mordant); Cream of Tartar
from 1 of 1 part to 1/2 of 1 part
th
For the making of Certaldite having yellow spots on the back ground or body
of a general red tint there is added to the bath described for red Certaldite about
/ part by weight of Sulphuric Acid-This colour effect can only be obtained in a
particular quality of gypsum containing impurities of basic nature which are
disposed in a certain patchy way and which tend to neutralize the sulphuric acid.
For the preparation of the bath for the making of Yellow Certaldite there are

page_text: used two baths the first is prepared with water (by weight) 200 parts; and Sulphate
of Iron 6 parts; and the second of the white bath (by weight) 200 parts; and
Bichromate of Potash 2 parts.-The material must first be dipped in the sulphate
of Iron bath and then in the Bichromate of Potash bath and then alternately in
these Baths until the surface remains wet after withdrawal as bereinbefore
described After the dippings the pieces are left to soak in the Sulphate of
Iron bath.
The following is another bath for the making of a yellow certaldite In preparing
it there is used of the white bath (by weight) 200 parts; and solid Extract of Yellow
wood or fustic (by weight) 4 to 6 parts
For making green certaldite there is used water 200 parts; alum 3 or 4 parts;
solid Extract of Yellow Wood 9.5 parts and sulphite of Indigo 9.5 parts or smaller
quantities of the last named two ingredients if a lighter hue are required.
A bath for the making of dark green Certaldite consists of water 200 parts;
Alum 2 parts; solid Extract of Yellow Wood 4 parts; and Sulphate of Iron 2 to 3
parts. The use of Sulphate of Iron enables the proportion of alum to be reduced
from that first described as the Sulphate of Iron aids in hardening and also
combines with the Yellow Wood to make colour.
A bath for making a lilac Certaldite is composed of the white bath hereinbefore
described 200 parts; solid Extract of Campeachy Wood 8 parts; and to this is added
a little carbonate of soda as much as may be necessary to neutralise the excess of
acid in the white bath Other alkaline matter may be used for this. purpose-The
hardening is done by the white bath and the Campeachy Wood gives colour.
It is important to neutralise the excess of acid in order to prevent the making of
a reddish tint-This may also be effected by using an equivalent amount of oxalate
of Ammonia in the place of the Oxalic Acid in the white bath.
For the preparation of a bath for the making of a sky blue Certaldite there is
used of the white bath 200 parts; Alum 6 parts; (in all ten parts of Alum); Yellow
Prussiate of Potash from 1/15,000th to 1/30,000th of a part-It is essential that the
alum used in this bath should contain traces of a soluble salt of Iron.
In making dark blue Certaldite there is used of the white bath 200 parts (by
weight); Aniline blue 1 part; and sulphuric acid 2 part. The Sulphuric Acid acts as
a solvent on the aniline blue-The blue which it is preferred to use is in Europe
distinguished by the letters B B B.
For making a Certaldite of a light Green or blue colour according to the quality
of the gypsum there is used water 200 parts; Sulphate of Copper 16 parts; liquor
ammoniæ (specific gravity 88) 20 parts; The Sulphate of Copper takes the place
of the alum for hardening and a portion of it also unites with the ammonia so as
to make the desired colouring matter.
In distinguishing the colour in all the foregoing cases I mean the colours to be
given to the main body or sulphate of lime part of the gypsum The colors or tints
of the impurities present in the gypsum will generally be of a dark shade and will
vary considerably with the kind of impurity and the effect thereon of the ingredients
composing the bath.
The material after being treated in one or some of the methods herein before
described and then thoroughly dried artificially or otherwise is scraped planed or
polished or otherwise brought to the necessary surface and then coated or impreg-
nated with paraffin stearin wax or other similar preservative substance..
Having now described and particularly ascertained the nature of the said Inven-
tion and the manner in which the same is or may be used or carried into effect I
would observe in conclusion that what I consider to be novel and original and
therefore claim as the Invention secured to me by the hereinbefore in part recited
Letters Patent is―
First The preparation of artificial stone or marble by submitting native gypsum
or sulphate of lime to the dehydrating and indurating treatment in the manner and
at the temperatures herein before described.
Secondly The preparation of colored artificial stone or marble by submitting

page_text: native gypsum or sulphate of lime to treatment in the manner at the temperatures
and in the baths herein before described.
Thirdly The method of preparing native gypsum or sulphate of lime for the
subsequent indurating process consisting in dehydrating it or partially dehydrating
it by submitting it to the action of gradually increasing and then gradually
decreasing temperatures as hereinbefore described.
Fourthly The method of indurating or hardening dehydrated or partially dehy-
drated native gypsum or sulphate of lime consisting in subjecting it to the impreg-
nating action of a solution or solutions of a salt or salts or a salt or salts and acid
or acids by impregnations with or immersions in the solution or solutions alternating
with drying intervals the impregnations or immersions and drying intervals being
continued until the surface of the article remains wet for some minutes after its
withdrawal from the bath so as to prepare it for the final immersion as herein before
described.
Fifthly The preparation of articles of artificial stone or marble by carving or
shaping to the desired form native gypsum or sulphate of lime then submitting the
samme to the dehydrating and indurating processes and then after drying treating
the same with stearin paraffin or wax or like preservative as hereinbefore described.
In witness whereof I the said John Henry Johnson have to this my
Specification set my hand and seal the seventeenth day of February One
thousand eight hundred and eighty three.
J. HENRY JOHNSON (L.S.)