IM: PROVEMENTS IN THE MANUFACTURE OF GLAZES OR ENAMELS FOR POTTERY WARE
Year: 1864

page_text: LETTERS PATENT to John Henry Johnson, of 47, Lincoln's Inn Fields,
in the County of Middlesex, Gentleman, for the Invention of "IM:
PROVEMENTS IN THE MANUFACTURE OF GLAZES OR ENAMELS FOR POTTERY
WARE." A communication from abroad by Dominique Grosjean, of
Cosseneu, near La Motte Beuvron, in the Empire of France,
Gentleman.
Sealed the 3rd January 1865, and dated the 2nd August 1864.
PROVISIONAL SPECIFICATION left by the said John Henry Johnson
at the Office of the Commissioners of Patents, with his Petition, on
the 2nd August 1864.
I, JOHN HENRY JOHNSON, of 47, Lincoln's Inn Fields; in the County of
Middlesex,. Gentleman, do hereby declare the nature of the said Invention
for "IMPROVEMENTS IN THE MANUFACTURE OF GLAZES OR ENAMELS FOR POTTERY.
WABE," a communication to me from abroad by Dominique Grosjean, of
Cosseneu, near La Motte Beuvron, in the Empire of France, Gentleman, to
be as follows:-
This Invention relates to the manufacture of certain glazes or enamels
suitable for pottery ware of all kinds, which glazes or enamels are perfectly
innoxious both to the user and to the manufacturer, by reason of the entire
absence in their composition of all deleterious or poisonous metallic oxides

page_text: objectionable in the glazes or enamels ordinarily employed, whilst at the same
time their cost is not augmented.
In carrying out this Invention for the manufacture of glazes or enamels,
which are to be applied to the articles of pottery ware by the ordinary
process of dipping, two successive operations or processes are employed.
The first process consists in the preparation of a fritt, and the second
process consists in effecting the intimate admixture of this fritt in proper
proportions with clay of a peculiar composition as herein-after described.
In the first process the Inventor employs the following ingredients, namely,
1, a clay constituting a multiple, silicate of alumina, of peroxide of iron, of
lime, and of potash; and it is further preferred to use a clay containing in the
calcined state about three times as much silica as it contains alumina, and
from one-quarter to two per cent. of potash or of soda or of potash and soda;
the sum of the bases contained in the clay should be about equal in weight
to one-half or two-thirds the weight of the silica contained in such clay; 2,
borax; 3, carbonate of soda, or a mixture of carbonate of soda and potash ;
4, sea salt.
The proportions which have been found to give a good result, but which
may be varied if desired, are-
Twenty parts by weight of baked clay of the nature above described.
Eight ditto ditto
of salts of soda or a mixture of equal parts of
of borax.
Eight ditto
ditto
Four
ditto
of sea salt.
salts of soda and of potash.
These ingredients are to be enclosed in a crucible and heated in a furnace
to a state of semi-fusion, in which state the mass is to be thrown into cold
water, when the desired fritt will be obtained.
In order to manufacture this fritt into a glaze or enamel suitable for glazing
or enamelling pottery ware, it is to be first reduced to a powder and intimately
mixed with about thirty parts by weight of clay of the description herein-before
mentioned, which has been washed and dried in the air. This mixture is to
be ground with water in a mill, and the result will be one of the improved
enamels or glazes herein-before referred to, which may be applied by dipping
the articles therein in the usual manner. Colors of any variety may be
obtained by adding to the glaze any of the well-known coloring matters,
taking care, however, not to employ those which contain heavy metallic oxides
of a poisonous nature.
When it is desired to produce highly transparent enamels or glazes, the
same process is employed as that herein-before described, with this exception

page_text: that for the baked clay used in preparing the fritt a corresponding amount of
white quartzy sand is substituted. This sand is first heated to a red heat, and
then thrown into cold water, after which it is to be reduced to a fine powder.
If desired, the baked clay which enters into the composition of the fritt may
be either wholly or partially replaced by unburnt clay; and in some cases it
is proposed to introduce into the composition of the fritt any suitable or
desirable quantities of lime, magnesia, or baryta, or of calcareous or other
substances of a like nature, in order to obtain varied results; and to add a
little borax in the second process, should it be found that the fritt obtained by.
the first process is not sufficiently fusible. Small quantities of fluoride of
calcium, phosphate of lime, and various silicates may also enter into the
composition of the said glazes or enamels, being added at will either to the
fritt or to the clay with which such fritt it mixed or used in both operations.
In case the clay employed shall contain less potash and soda than the pro-
portions herein-before given, it is proposed to increase proportionately the
quantities of alkaline carbonates employed in preparing the fritt.
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 2nd February 1865.
TO ALL TO WHOM THESE PRESENTS SHALL COME, I, JOHN
HENRY JOHNSON, of 47, Lincoln's Inn Fields, in the County of Middlesex,
Gentleman, send greeting.
WHEREAS Her most Excellent Majesty Queen Victoria, by Her Letters
Patent, bearing date the Second day of August, in the year of our Lord
One thousand eight hundred and sixty-four, in the twenty-eighth year of
Her reign, did, for Herself, Her heirs and successors, give and grant unto
me, the said John Henry Johnson, Her special license that I, the said
John Henry Johnson, my executors, administrators, and assigns, or
such others as I, the said John Henry Johnson, my executors adminis-
trators, or assigns, should at any time agree with, and no others,
from time to time and at all times thereafter during the term therein ex-
pressed, should and lawfully might make, use, exercise, and vend, within the
United Kingdom of Great Britain and Ireland, the Channel Islands, and
Isle of Man, an Invention for "IMPROVEMENTS IN THE MANUFACTURE OF GLAZES
OR ENAMELS FOR POTTERY WARE," a communication to me from abroad by Domi-
nique Grosjean, of Cossenen, near La Motte Beuvron, in the Empire of France,

page_text: Gentleman, upon the condition (amongst others) that I, the said John
Henry Johnson, my executors or administrators, by an instrument in writing
under my hand and seal, or under the hand and seal of one of them, should
particularly describe and ascertain the nature of the said Invention, and in
what manner the same was to be performed, and cause the same to be filed
in the Great Seal Patent Office within six calendar months next and
immediately after the date of the said Letters Patent.
NOW KNOW YE, that I, the said John Henry Johnson, do hereby
declare the nature of the said Invention, and in what manner the same
is to be performed, to be particularly described and ascertained in- and by
the following statement, that is to say :-
The said Invention relates to the manufacture of certain glazes or enamels
suitable for pottery ware of all kinds, which glazes or enamels are perfectly
innoxious both to the user and to the manufacturer, by reason of the entire
absence in their composition of all deleterious or poisonous metallic oxides
so objectionable in the glazes or enamels ordinarily employed, whilst at the same
time their cost is not augmented.
In carrying out this Invention for the manufacture of glazes or enamels,
which are to be applied to the articles of pottery ware by the ordinary process
of dipping, two successive operations or processes are employed.
The first process consists in the preparation of a fritt, and the second process
consists in effecting the intimate admixture of this fritt in proper proportions
with clay of a peculiar composition as herein-after described...
In the first process the Inventor employs the following ingredients, namely,
1, a clay constituting a multiple, silicate of alumina, of peroxide of iron, of
lime, and of potash; and it is further preferred to use a clay containing in the
calcined state about three times as much silica as it contains alumina, and
from one-fourth to two per cent. of potash or of soda, or of potash and soda;
the sum of the basis contained in the clay should. be about equal in weight
to one-half or two-thirds the weight of the silica contained in such clay; 2,
borax; 3, carbonate of soda, or a mixture of carbonate of soda and potash;
4, sea salt.
The proportions which have been found to give a good result, but which
may be varied if desired, are―
20 parts by weight of baked clay of the nature above described.
8 do.
1
do.
of borax.
da
of colta of code
mixture of
لمسمم
f
8. do.
do.
of borax.
8 10.
do.
4 do.
.do.
of colts of code or a mixture of equal parts of
salts of soda and of potash.
of sea salt.

page_text: These ingredients are to be enclosed in a crucible and heated in a furnace
to a state of semi-fusion, in which state the mass is to be thrown into cold
water, when the desired fritt will be obtained.
In order to manufacture this fritt into a glaze or enamel suitable for-glazing
or enamelling pottery ware, it is to be first reduced to a powder and intimately
mixed with about thirty parts by weight of clay of the description herein-before
mentioned, which has been washed and dried in the air. This mixture is to
be ground with water in a mill, and the. result will be one of the improved
enamels or glazes herein-before referred to, which may be applied by dipping the
articles therein in the usual manner. Colors of any variety-may be obtained-by
adding to the glaze any of the well-known coloring matters, taking care, how-
ever, not to employ those which contain heavy metallic oxides of a poisonous
nature.
When it is desired to produce highly transparent, enamels or glazes, the
same process is employed as that herein.before described, with this exception,
that for the baked clay used in preparing the fritt a corresponding amount
of white quartzy sand is substituted. This sand is first heated to a red heat,
and then thrown into cold water, after which it is to be reduced to a fine
powder. If desired, the baked clay which enters into the composition of the
fritt may be either wholly or partially replaced by unburnt clay; and in some
cases it is proposed to introduce into the composition of the fritt any suitable
or desirable quantities of lime, magnesia, or baryta, or of calcareous or other
substances of a like nature, in order to obtain varied results; and to add a
little borax in the second process, should it be found that the fritt obtained
by the first process is not sufficiently fusible. Small quantities of fluoride of
calcium, phosphate of lime, and various silicates may also enter into the
composition of the said glazes or enamels, being added at will either to
the fritt or to the clay with which such fritt is mixed or used in both
operations.
In case the clay employed shall contain less potash and soda than the
proportions herein-before given, it is proposed to increase proportionately
the quantities of alkaline corbonates employed in preparing the fritt.
It is also proposed to apply a white glaze or enamel to Fayence ware of
all kinds and of all colors, without introducing into such white glaze any
deliterious oxide, and without the intervention of stanniferous or plumbiferous
preparations.
For this purpose the enamels or glazes herein-before described are employed,
prepared with white silicates of alumina. When it is desired to cover a
colored paste or clay with a white glaze or enamel, a coating of white clay is

page_text: first applied to the surfaces to be glazed, such white clay being free from
oxide of iron and from oxide of manganese. The whole is then fired, after
which the white glaze is applied and the article is again fired.
Having now described and particularly ascertained the nature of the said
Invention, 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 herein-
before in part recited Letters Patent, is,-
First, the manufacture of innoxious glazes or enamels for pottery ware of all
kinds substantially as herein-before described.
Second, the application and use to pottery ware of all kinds of innoxious
glazes or enamels of the nature herein-before set forth.
In witness whereof, I, the said John Henry Johnson, have hereunto set
my hand and seal, this Second day of February, in the year of our
Lord One thousand eight hundred and sixty-five.