A New Pigment or Paint Base and Processes of Producing the same.
Year: 1889

page_text: Date of Application, 8th Oct., 1889
Complete Specification Left, 18th July, 1890-Accepted, 23rd Aug., 1890
PROVISIONAL SPECIFICATION.
[Communicated from abroad by JAMES PLINY PERKINS, of No. 115, Broadway,
New York City, United States of America, Inventor and Manufacturer.]
A New Pigment or Paint Base and Processes of Producing
the same.
I, WILLIAM LLOYD WISE, of No. 46, Lincoln's Inn Fields, in the County of
Middlesex, Consulting Engineer and Patent Agent, do hereby declare the nature of
this invention to be as follows:-
This invention relates to a new product to be used as a pigment or paint base, or as
a combined red pigment and paint base which can be produced commercially in
different ways, and to processes of producing the same.
By this invention a variety of bright red pigments of the most pronounced color
can be produced. These colors belong to the class commonly known as Venetian
reds. One process of producing such pigments is as follows:-Silicious ferruginous
slag is employed as the raw material: it is most commonly found as a bye-product in
the manufacture and working of wrought iron, though it may be produced in other
ways in a form suitable for the application of the process.
The best quality of this slag is produced in puddling and reheating furnaces. It is
nearly black in color and of great specific gravity, and consists of nearly pure
silicate of iron mixed with ferrous oxide. This slag, as above described, is pulverised
in any suitable apparatus to the degree of fineness known as "190 mesh" or more.
It is not necessary that it should be pulverised to a degree finer than that, and the
process may be carried out with a fair degree of success with slag ground to a lesser
degree of fineness than that mentioned.
The second step in the process consists in treating the slag pulverised as above
described, with sulphuric acid. The acid. may be mixed with the pulverised slag in
the ordinary way by stirring with spades or paddles, or in any suitable mechanical
mixer or mixing machine. The amount of sulphuric acid to be mixed with a given
quantity of pulverised slag varies according to the quality of, the slag and the
particnlar shade of color which it is desired the resulting piginent shall present. In
general, however, with the average slag and the average quality of acid, the best
results have been obtained when the proportion, by weight, of the acid to the slag has
been as one to three. In certain cases, however, a higher proportion of acid than
that of one to three may be necessary. The acid may be used undiluted in its
commercial form of oil of vitriol, or it may be diluted with water, and this method of
applying it is considered preferable as its action is slower, more moderate, and more
uniformly diffused through the mass of pulverised slag. When undiluted the action
of the acid is intense, local and uneven. It attacks too violently those particles with
which it first comes in contact, and being absorbed by those does not get to the other
particles. Another method of obtaining the same effect as that resulting from the
dilution of the acid is to dampen or moisten the pulverised slag with the given
quantity of water before applying the undiluted acid. The result is obviously the
same, though it is deemed preferable to dilute the acid first and then apply the dilute
solution to the dry pulverised slag.
The perceptible effects of this, the second step in the process, are the liberation of
heat and the caking or solidification of the mass of slag. What was formerly a fine
powder becomes a solid mass, though brittle and easily broken up. The color of the
mass changes from the dark shade which the slag had after pulverisation, to a grey or
whitish tinge. If water was used to dilute the acid as above described a considerable

page_text: quantity of steam is given off during this step of the process, and if acid is used in
undiluted form, a certain amount of steam is still given off during this step of the
process.
The third step in the process consists in heating the substance produced by the
steps hereinbefore described to a red heat in any suitable furnace. The caked mass
remaining after the completion of the second step of the process should be broken up
so as to be capable of convenient handling and introduction into the furnace. The
furnace should be so constructed as to admit of the escape of the fumes given off on
heating the charge and to allow access of air when desired.
The result of the process of treating slags of the nature described, in the manner
above set out, is a bright red pigment of the most desirable of those shades known as
Venetian red. The pigment is of a soft nature and can easily be ground to an
impalpable smooth powder. This pigment has strong and lasting coloring powers, it
mixes and blends easily with other pigments, and grinds perfectly with oil. The
ground pigment is free from grit, and of unusual smoothness.
Chemical analyses of the resulting product of this process of treating slag tend to
show that it consists of an intimate mixture of ferric oxide and separated or precipitated
silica.
During the application of heat in the third step of the process, sulphuric dioxide
gas passes off in fumes.
As before stated the shade of color in the pigments produced by this process may
be varied by varying the amount of sulphuric acid used, the brighter reds being
produced when the larger quantity of acid is used, and the darker ones when a less
quantity of acid is used.
The pigments produced by this process are brighter and more pronounced in color,
and are more homogeneous in composition than any that can so far as I know be made
by the mixture of the ordinary Venetian reds with the ground silica.
According to a modification of the foregoing process, after pulverising the slag the
second step consists in subjecting the pulverised slag to the action of heat with
access of air. This calcining which is effected in a suitable furnace changes the color
of the pulverised slag from a black or slate color to a dark reddish or seal brown.
The third step in this process consists in treating the slag which has been pulverised
and calcined as above described, with sulphuric acid. The acid may be mixed with
the pulverised or calcined slag in the ordinary way by stirring with 'spades or paddles,
or in any suitable mechanical mixer or mixing machine. The amount of sulphuric
acid to be mixed with a given quantity of pulverised and calcined slag varies
according to the quality of the slag and the particular shade of color which it is
desired the resulting pigment shall present. The amount of acid, however, is always
much less than that required when treating the pulverised slag with sulphuric acid
without the intermediate step of heating or caleining.
In this process also the same effect as that resulting from the dilution of the acid
can be obtained by damping or moistening the pulverised slag with the given quantity
of water before applying the undiluted acid; but, as in the preceding process, it is
considered preferable to dilute the acid and then apply the dilute solution to the dry
'pulverised slag.
The fourth step in this process consists in heating the substance produced by the
steps herein-before described to a red heat in any suitable furnace; the caked mass
remaining after the completion of the third step in the process should be broken up so
as to be capable of convenient handling and introduction into the furnace. The
furnace should be so constructed as to perimit the escape of the fumes given off on the
heating of the charge and to allow access of air when desired.
Dated this 8th day of October 1889.

page_text: COMPLETE SPECIFICATION.
A New Pigment or Paint Base and Processes of Producing
the same.
A communication from JAMES PLINY PERKINS, of No. 115, Broadway, New York City,
U.S.A., Inventor and Manufacturer.
I, WILLIAM LLOYD WISE. of No. 6 Lincoln's Inn Fields, in the County of
Middlesex, Consulting Engineer and Patent Agent, 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 invention relates to a new product to be used as a pigment or paint base,
or as a combined red pigment and paint base, which can be produced commercially in
different ways and to processes of producing the same.
By this invention a variety of bright red pigments of the most pronounced color
can be produced. These colours belong to the class commonly known as Venetian
reds. The said product consists of an intimate mixture of ferric oxide and separated
or precipitated silica and the shade of red produced can be varied by varying the
proportions of the constituent parts, but when these are combined in the proportions
preferred of about twenty-five parts silica to seventy-five parts ferric oxide, a bright
red pigment of the most desirable shade is produced.
One process of producing such pigments is as follows:-
Silicious ferruginous slag is employed as the raw material; it is most commonly
found as a bye-product in the manufacture and working of wrought iron, though it
may be produced in other ways in a form suitable for the application of the
process.
The best quality of this slag is produced in puddling and reheating furnaces. It is
nearly black in colour and of great specific gravity, and consists of nearly pure silicate
of iron mixed with ferrous oxide.
This slag is pulverised in any suitable apparatus to the degree of fineness known as
190 mesh" or more. It is not necessary that it should be pulverized to a degree
finer than that, and the process may he carried out with a fair degree of success with
slag ground to a lesser degree of fineness than that mentioned.
The second step in the process consists in treating the slag pulverised as above
described with sulphuric acid. The acid may be mixed with the pulverised slag in the
ordinary way by stirring with spades or paddles, or in any suitable mechanical mixer or
mixing machine. The amount of sulphuric acid to be mixed with a given quantity of
pulverised slag varies according to the quality of the slag and the particular shade of
color which it is desired the resulting pigment shall present. In general, however,
with the average slag and the average quality of acid, the best results have been
obtained when the proportion, by weight, of the undiluted acid to the slag has been as
one to three. In certain cases however, a higher proportion of acid than that of one
to three may be necessary. The acid may be used undiluted in its commercial form of
oil of vitriol, or it may be diluted with about three parts of water to one of undilute
acid, or sufficient to moisten or thoroughly permeate the slag being operated upon, and
this method of applying it is considered preferable, as its action is slower, more
moderate, and more uniformly diffused through the mass of pulverised slag. When
undiluted the action of the acid is intense, local and uneven. It attacks too violently
those particles with which it first comes in contact, and, being absorbed by those, does
not get to the other particles. Another method of obtaining the same effect as that
resulting from the dilution of the acid, is to dampen or moisten the pulverised slag
with the given quantity of water before applying the undiluted acid. The result is
obviously the same, though it is deemed preferable to dilute the acid first and then
apply the dilute solution to the dry pulverised slag.
The perceptible effects of this, the second step in the process, are the liberation of
heat and the caking or solidification of the mass of slag. What was formerly a fine

page_text: powder becomes a solid mass, though brittle and easily broken up. The color of the
mass changes from the dark shade which the slag had after pulverisation. to a grey or
whitish tinge. If water be used to dilute the acid, as above described, a considerable
quantity of steam will be given off during this step of the process, and if acid be used
in undiluted form, a certain amount of steam will be still given off during this step of
the process.
The third step in the process consists in heating the substance produced by the steps
hereinbefore described to a red heat in any suitable furnace. The caked mass remin
ing after the completion of the second step of the process should be broken up, so as
to be capable of convenient handling and introduction into the furnace. When first
introduced into the furnace, the treated slag should be subjected to a low red heat, and
should at no time be heated to above 1800° or a very light ref, but not approaching
a white heat. The length of time required is appoximately from two to four and a
half hours according to the degree of lieat applied, and the amount of moisture in the
treated slag when placed in the furnace and which moisture must be evaporated. The
duration of this heat ng process is determined by taking small samples from the
furnace at short intervals, allowing them to cool so that the material may develope its
color, and applying the usual test with litmus paper to determine the absence of free
acid, when the process will be finished.
The furnace should be so constructed as to admit of the escape of the fumes given
off on heating the charge, and to allow access of air when desired.
The result of the process of treating slags of the nature described, in the manner
above set forth, is a bright red pigment of the most desirable of those shades known
as Venetian red. The pigment is of a soft nature, and can easily be ground to an
impalpable smooth powder. This pigment has strong and lasting coloring powers, it
mixes and blends easily with other pigments, and grinds perfectly with oil. The
ground pigment is free from grit and of unusual smoothness. Chemical analyses of
the resulting, product of this process of treating slag show that it consists of an
intimate mixture of ferric oxide and separated or precipitated silica in the proportion
of about 25 parts silica to 75 parts of the oxide. Considerable variations from these
proportions still give pigments of desirable shades of red, but the most enduring
pigment of the most popular of the colors, known as Venetian reds, is that resulting
from the admixture of these elements in the above named proportion of 25 to 75.
During the application of heat in the third step of the process, sulphuric dioxide gas
passes off in the fumes.
As before stated, the shade of color in the pigments produced by this process may
be varied by varying the amount of sulphuric acid used, the brighter reds being
produced when the larger quantity of acid is used, and the darker ones when a less
quantity of acid is used.
The pigments produced by this process are brighter and more pronounced in color,
and are more homogeneous in composition, than any that can, so far as I know, be
made by the mixture of the ordinary Venetian reds with ground silica.
This process produces a mixture of ferric oxide with silica in the separated and
precipitated and extremely fine condition which it assumes when it is set free from
the certain silicates decomposable by acids and then heated. In the separated or pre-
cipitated condition silica is finer and more pulverulent than it can be when produced
by the most complete grinding of quartz rock or quartzose mineral, for the particles
thus obtained by grinding will consist of particles of large crystals in the crystalline
condition, also, separated or precipitated silica is opaque, while the minute particles of
crystals or crystalline rock obtained by grinding would be transparent or translucent,
consequently it is believed that this is the reason why pigments produced by this
process are so much more pronounced in color than the weaker, lighter shades produced
by mixing ordinary Venetian reds with ground silica. Separated or precipitated
silica has, furthermore, a much greate, power to hold, or bind colors than crystalline
silica.
. Separated or precipitated silica is apparently neutral so far as concerns the dimming

page_text: or affecting the color of the ferric oxide with which it is mixed in the proportions
resulting from the operation of this process.
According to a modification of the foregoing process, after pulverising the slag the
second step consists in subjecting the pulverized slag to the action of heat, with access
of air.
For this purpose the dry slag is introduced into a suitable calcining furnace in
which it may cover the bottom thereof to a greater depth than is the case when the
slag is previously treated with sulphuric acid. It should at first be subjected to a low
cherry red heat, and stirred or agitated to permit of thorough access of air, the
heat meanwhile being gradually raised during the period of say, from one to two hours,
when an ordinary red heat shall have been obtained. When removed from the furnace
and allowed to cool, the color of the natural pulverised slag will be found to have
changed to a reddish or seal brown.
The third step in this process consists in treating the slag, which has been pulverised
and calcined as above described, with sulphuric acid. The acid may be mixed with
the pulverised or calcined slag in the ordinary way by stirring with spades or paddles,
or in any suitable mechanical mixer or mixing machine. The amount of sulphuric
acid to be mixed with a given quantity of pulverised and calcined slag varies according
to the quality of the slag and the particular shade of color which it is desired the
resulting pigment shall present. The amount of acid, however, is always much less
than that required when treating the pulverised slag with sulphuric acid without the
intermediate step of heating or calcining.
In this process as in that previously described, the acid may be used undiluted, in
its commercial form of oil of vitriol or it may be diluted with water, and I prefer this
method of applying it for the reasons hereinbefore stated.
In this process also the same effect as that resulting from the dilution of the acid
can be obtained by damping or moistening the pulverised slag with the given quantity
of water before applying the undiluted acid; but, as in the preceding process, it is
considered preferable to dilute the acid and then apply the dilute solution to the dry
pulverised slag.
The perceptible effects of this, the third step in the present process, are the same as
those already explained with reference to the second step in the process hereinbefore
described.
The fourth step in the present process consists in heating the substance produced by
the steps herein before described to a red heat in any suitable furnace. The mechanical
treatment of the mass in this fourth step is substantially the same as that set forth in
The caked mass
the second step of the present process hereinbefore described.
remaining after the completion of the third siep in the process should be broken up
so as to be capable of convenient handling and introduction into the furnace. The
furnace should be so constructed as to permit the escape of the fumes given off on the
beating of the charge and to allow access of air when desired.
The result of this process of treating slags, of the nature described, in the manner
above set forth, is a bright red pigment similar to that described as the product of the
other process hereinbefore specified.
During the application of heat in the fourth step of the process, sulphuric dioxide
gas passes off in fumes.
As stated with reference to the other process herein before described the shade of
color in the pigment produced by the present process may be varied by varying the
amount of sulphuric acid used, the bright reds being produced when the larger
quantities of acid are used, and the darker ones when a less quantity of acid
is used.
By the process just described as compared with that previously described herein for
producing the same or a similar pigment a considerable saving can be effected in the
amount of sulphuric acid used. Therefore in localities where sulphuric acid is
expensive and fuel is comparatively cheap the process last bereinabove described
would be preferable to that previously described herein as above referred to.

page_text: Having now particularly described and ascertained the nature of the said inven-
tion and in what manner the same is to be performed I declare that what I
claim is :-
1. The manufacture of the herein described new red pigment or paint base consisting
of an intimate mixture of ferric oxide and separated or precipitated silica.
2. The manufacture or production of a red pigment or paint base from silicious
ferruginous slag, by pulverising the slag, then treating it with. sulphuric acid, and
afterwards heating the resulting mass substantially as hereinabove described.
3. The manufacture or production of a red pigment or paint base from silicious
ferruginous slag, by pulverising the slag, then heating it with access of air, then
treating it with sulphuric acid, and applying heat to the resulting mass as hereinabove.
described.
Dated this 18th day of July 1890.
W. LLOYD WISE.
Per F. J. Brougham.