IMPROVEMENTS IN THE MANUFACTURE OF ENAMELLED WROUGHT OR SHEET A com- IRON, AND OF MATERIALS OR COMPOUNDS EMPLOYED THEREFOR."
Year: 1877

page_text: LETTERS PATENT to William Robert Lake, of the Firm of Haseltine, Lake,
& Co., Patent Agents, Southampton Buildings, London, for the Invention of
"IMPROVEMENTS IN THE MANUFACTURE OF ENAMELLED WROUGHT OR SHEET
A com-
IRON, AND OF MATERIALS OR COMPOUNDS EMPLOYED THEREFOR."
munication from abroad by Eben Colby Quinby and Joseph Cary Whiting,
both of Saint Louis, Missouri, United States of America, Gentlemen.
PROVISIONAL SPECIFICATION left by the said William Robert Lake at the
Office of the Commissioners of Patents on the 7th August 1877.
WILLIAM ROBERT LAKE, of the Firm of Haseltine, Lake, & Co., Patent Agents,
Southampton Buildings, London. "IMPROVEMENTS IN THE MANUFACTURE OF
ENAMELLED WROUGHT OR SHEET IRON, AND OF MATERIALS OR COMPOUNDS
EMPLOYED THEREFOR." [A communication from abroad by Eben Colby Quinby and
Joseph Cary Whiting, both of Saint Louis, Missouri, United States of America,
Gentlemen.]
The said Invention relates to the production of enamelled surfaces on wrought or
sheet iron by the employment of the improved enamel or crystal materials, and
the novel processes herein-after described.
The said Invention consists,-
1st. In a new enamel glass or crystal.
2nd. In the employment of clay in the enamel coating for sheet-iron and enamel
ware.
3rd. In the addition of carbonate of magnesia to the compound which forms the
said enamel coating for the purpose of rendering the same more opaque and
assisting in the spotting, mottling, or flecking of the enamel ware.
4th. In.the addition of sulphate of magnesia to the said enamel coating for the
purpose of assisting the enamelling of mottled wrought or sheet-iron ware.
5th. In the employment of arsenious acid in the said enamel coating for
effecting a more perfect adhesion of the enamel coating to the iron base.

page_text: 6th. In the manufacture of mottled sheet-metal enamelled ware wherein the
mottles are developed in the enamel coat during the drying and baking processes
which are carried on as herein-after set forth.
7th. In the employment of processes whereby an enamel glass and an enamel
coat are so produced and applied to sheet metal ware as to produce a thin glazed and
mottled enamel on the surface of such ware.
The first considerations of a good enamel for wrought or sheet iron wares, more
particularly for household purposes, to which this Invention is chiefly, though not
exclusively applicable, is durability, which is referable, first, to its adhesiveness
whereby it clings to the iron and resists separation from it; and second, to the
thinness of the enamel, which renders it more pliable, and consequently but slightly
liable to break or check when the iron and itself are subjected to strain by
accident or otherwise.
Beauty of color, or ornament, and brilliancy of finish, are secondary considerations
not to be disregarded, but still not to be sought after at the expense of durability,
and the chief object of this Invention is to secure in enamelled wrought or sheet
iron wares both durability and beauty to a degree not heretofore reached, by
operations simpler and more direct than heretofore practised in the work of
enamelling on wrought or sheet iron. This work, as ordinarily conducted, con-
templates the employment of two or more coats of enamel, that is to say, a body
coat prepared especially to unite the iron with itself, and a second coat or coating
which is usually colored with some metallic oxide, and is intended to impart finish
to the article; and there is often a third coat especially adapted for glazing or
imparting polish to the whole; and this process of enamelling comprehends many
repetitions not necessary in practising this Invention, and gives an inferior enamel
coating; and the said Invention comprises the composition of an enamel glass or
crystal, and also a manner of applying the same, with other ingredients, as a coating
for sheet-iron ware. And first, as to the composition of this enamelled glass or
crystal. The same consists of silica, 100 lbs.; soda ash, 35 lbs.; borax, 75 lbs. ;
plaster of Paris or gypsum, 20 lbs., or 10 to 20 lbs.; and arsenious acid in the pro-
portion of one and one-eighth per cent. of all the other ingredients.
These proportions may be varied to some extent, but as given, have been found
to work well. When these ingredients are compounded, as herein-after set forth,
the result is an enamel glass or crystal, vitreous enough to carry a glaze of itself
with an affinity for wrought or sheet iron, which causes it to adhere thereto with
extreme tenacity when employed, as set forth, and burned upon it, and which will
not exfoliate or absorb moisture in quantity sufficient to destroy its polish.
Such of the above-mentioned ingredients of the said enamel glass or crystal as
require it having been comminuted, all are carefully mixed together and brought
to a state of complete vitrification in a reverberatory oven. This done, the enamel
glass or crystal is run off as usual into water to granulate it, when it is ready for
grinding.
In making an enamel for wrought or sheet-iron ware I take, say 100 lbs. of this
enamel glass or crystal, and grind the same in an ordinary porcelain mill, adding
thereto about five (5) lbs. of clay, which helps to give body to the enamel and to
prevent its crazing when it is finally fixed on the iron in the heat of a muffle.
In most cases it is preferable to introduce along with the enamel glass and clay
in the grinding process calcined carbonate of magnesia in the proportion of 8 oz.
to 100 lbs. of the enamel glass.
Prepared as above set forth the mixture is run off through a strainer into tubs,
where it is allowed to remain about one day, during which time a sort of ripening
is effected, when it is finally prepared as follows:-The mixture being brought to
about the consistency of cream, by the addition, when necessary, of water, dilute
sulphate of magnesia is added until the consistency of the mixture is such that it
will no longer run like water upon the surface of the article when applied, or upon
the surface of the mixing spoon, but is coagulated and pasty, yet still capable. of
being shaken out into a thin and uniform coat. Two ounces of sulphate of magnesia

page_text: have usually been found sufficient for 100 lbs. of the mixture; and if during the
coating process the paste or mixture beco:nes thin and watery, as much of the water
as rises to the surface is removed during a slight intermission of the dipping
process, and then the paste is brought to a proper consistency again by the appli-
cation of dilute sulphate of magnesia. The same result may be measurably accom-
plished by the use of sulphate of magnesia in the mill during the grinding process.
For instance, when the grinding operation is intermitted the tendency of the ingre..
dients in the mill being to settle rapidly, the upper stones are liable to become
clogged, in which case the mill is again started with difficulty. To avoid this
result the grinding operation is usually made continuous until it is completed. But
this continuous grinding is rendered unnecessary in practising this Invention by the
introduction into the mixture of a small quantity of sulphate of magnesia.
The mixture having been finally prepared as above set forth, the wrought or
sheet-iron article to be enamelled is dipped therein, the same having been first
prepared by the well-known processes of annealing, pickling, scouring, and
washing. Care should be taken that the enamel coating is not laid on too heavily,
and that it is evenly distributed.
This
Having received a thin uniform coat by dipping, the article so coated is dried, for
if the enamel coat is burned while still wet or damp it will crack or craze.
drying is accomplished in an oven, the range of heat in which varies from about
100° to 170°, but the drying may be accomplished, even at summer heat, in an
ordinary close room.
One of the objects of this Invention being to produce a beautifully mottled or
spotted enamel coat, a variant character is given to the surface by varying the
temperature at which the drying is accomplished within the range as above set
forth. The higher the temperature the smaller and less distinct the spots; the
lower the temperature the more pronounced the mottling.
The burning process is effected in an ordinary muffle at a red or cherry heat, or a
little above the ordinary time required, being about four minutes. The result is a
beautifully mottled enamel coat, and one which sticks to the iron base with great
tenacity.
If the arsenious acid is omitted from the enamel glass, the enamel coat produced,
as herein specified, will be less adhesive, and as a consequence will be less valuable
for our purposes than when the said acid is used; and a quantity about as specified,
namely, 2/2 lbs. to 100 of silica, or to 230 lbs. of all the other ingredients of the
enamel glass, gives an enamel of the required quality.
In carrying this Invention into practice we prefer to employ one coat and one
burning.

page_text: SPECIFICATION in pursuance of the conditions of the Letters Patent filed by
the said William Robert Lake in the Great Seal Patent Office on the 7th
February 1878.
WILLIAM ROBERT LAKE, of the Firm of Haseltine, Lake, & Co., Patent
Agents, Southampton Buildings, London. "IMPROVEMENTS IN THE MANUFACTURE
OF ENAMELLED WROUGHT OR SHEET IRON, AND OF MATERIALS OR COMPOUNDS
EMPLOYED THEREFOR." A communication from abroad by Eben Colby Quinby and
Joseph Cary Whiting, both of Saint Louis, Missouri, United States of America,
Gentlemen.
The nature of this Invention consists,-
First. In a new enamel glass or crystal to form a coat.
Second. In the employment of clay in the said enamel coat for sheet-iron
enamelled ware.
Third. In the addition of carbonate of magnesia to the compound which forms
the said enamel coat for the purpose of rendering the coat more opaque, and
assisting in the spotting, mottling, or flecking of the enamelled ware.
Fourth. In the addition of sulphate of magnesia to enamel coatings for the
purpose of assisting in the enamelling of mottled wrought or sheet-iron ware.
...Fifth. In the use of arsenious acid in the enamel coat for the purpose of affecting
a more perfect sticking or adherence of the enamel coat to the iron base.
Sixth. In a combination of processes whereby an enamel glass and an enamel
coat are produced and applied to sheet-metal ware to produce such ware with a
thin glazed and mottled enamel on its surface.
Seventh. In the manufacture of mottled sheet-metal enamelled ware, wherein
the mottles are developed in the enamelling coat during the drying and baking
processes which are carried on as herein-after set forth.
The most important consideration in an enamel for wrought or sheet iron wares
is that of durability, more particularly when this ware is designed for household
purposes, to which the said Invention is chiefly applicable, though not confined
to the same.
This quality of durability is referable, first, to the adhesiveness of
the material whereby it clings to the iron and resists separation from it; and,
second, to the thinness of the enamel, which renders it more pliable, and conse-
quently less liable to break or check when with the iron it is subjected to strain
by accident or otherwise.
Beauty of colour or ornament and brilliancy of finish are secondary considerations
not to be disregarded, but still not to be sought after at the expense of durability.
And the chief object of this Invention is to secure in enamelled wrought or sheet
iron wares both durability and beauty to a degree not heretofore reached, and by
operations simpler and more direct, as I believe, than heretofore practiced in the
art of enamelling on wrought or sheet iron. This art, as ordinarily conducted,
involves the employment of two or more coats of enamel, namely, a body coat
prepared especially with the view to unite with the iron, and a second coat which
is usually colored with some metallic oxide, and is intended to impart finish and
ornament to the article; and there is often a third coat over both of these especially
adapted for glazing or imparting polish to the whole; and this process of enamelling
comprehends many repetitions not necessary in my improved process, and gives au
inferior enamel coating.
The said improved process comprises the composition of an enamel glass or
crystal, and also the manner of applying the same with other ingredients as a coating
to sheet-iron wares. In the composition of the said enamel glass or crystal I take
silica, 100 pounds; soda ash, 35 pounds; borax, 75 pounds; plaster of Paris or
gypsum, 20 pounds, or 10 to 20 pounds; and arsenious acid in the proportion of
one and one-eighth per cent. of all the other ingredients.
These proportions may be varied to some extent, but those above given have

page_text: been found to work well. When these are compounded as herein-after set forth,
the resultant mixture is an enamel glass or crystal, vitreous enough to carry a
glaze of itself with an affinity for wrought or sheet iron, which causes it to adhere
thereto with extreme tenacity when employed as herein set forth and burned upon
it, and which will not exfoliate or absorb moisture in quantity sufficient to destroy
its polish.
Such of the above-mentioned ingredients of the said enamel glass or crystal as
require it having been comminuted, all are carefully mixed together and brought to
a state of complete vitrification in a reverberatory oven with observance of the
rules applicable to glass making generally. Then the enainel glass or crystal is
run off as usual into water to granulate it when it is ready for grinding.
For making an enamel for wrought or sheet-iron ware I take, say, 100 pounds
of this enamel glass or crystal, and grind the same in an ordinary so-called porcelain
mill, adding thereto about five (5) pounds of clay, preferably white, and having a
pronounced soapy feeling, which clay helps to give body to the enamel, and to
prevent its crazing when it is finally fixed on the iron in the heat of a muffle.
This grinding process requires about one working day, but should always be con-
tinued until the enamel glass or crystal is thoroughly ground, and the clay
thoroughly mixed with it.
In most or all cases I have further found that it is best to introduce along with
the enamel glass and clay in the grinding process calcined carbonate of magnesia
in the proportion of 8 ounces to 100 pounds of the enamel glass.
This salt of magnesia serves to make the enamel coat as finally applied less
transparent, contributes to the flecking or spotting of it with white, and thus in a
measure prevents the iron base from imparting to the enamel coat throughout its
own dull and unattractive shade.
Prepared as above set forth, the mixture is run off through a strainer into tubs,
where it is allowed to remain about one day, during which time a sort of ripening
is effected, when it is finally prepared as follows:-The said mixture being brought
to about the consistency of cream by the addition when necessary of water, dilute
sulphate of magnesia is added until the consistency of the mixture is such that it
will no longer run like water upon the surface of the article when applied or upon
the surface of the mixing spoon, but is coagulated and pasty, yet still capable of
being shaken out into a thin and uniform coat. Two ounces of sulphate of magnesia.
have usually been found sufficient for 100 lbs. of this mixture; and if, as some-
times happens during the coating process, the paste or mixture becomes thin and
watery I carefully remove as much of the water as rises to the surface during a
slight intermitting of the dipping process, and then bring the paste to a proper
consistency again by the application as above specified of sulphate of magnesia.
The same result may be measurably accomplished by the use of sulphate of
magnesia in the mill during the grinding process. For instance, when the grinding
operation is intermitted, say, at the noon hour, the tendency of the ingredients in
the mill being to settle rapidly, the upper stones, which in this operation are drawn
över the lower or bed stone by bent arms, are apt to become clogged, in which case
the mill is again started with difficulty. To avoid this inconvenience the grinding
operation is usually made continuous until it is completed. But by this Invention
this continuous operation is rendered unnecessary by the introduction into the
mixture of a small quantity of sulphate of magnesia; and the above-named
desirable result is accomplished while the consistency necessary for the final
application of the enamel coat is secured.
The aforesaid mixture having been finally prepared as above set forth, the
wrought or sheet iron article to be enamelled is dipped into it, the same having
been first prepared by the well-known processes of annealing, pickling, scouring,
and washing. For washing the article clear water is used, the wrought or sheet
iron remaining therein until it is dipped. Care should be taken that the ename!
coating be not laid on too heavily, and that it be evenly distributed.

page_text: Having received a thin uniform coat by dipping, the article so coated is dried,
for if the enamel coat is burned while still wet or damp it will crack or craze.
This drying is accomplished for convenience and dispatch in an oven constructed
for the purpose; the range of heat in which oven varies from about 100° to 200°
Fahrenheit, but the drying may be accomplished even at summer heat in an
ordinary close room.
One of the objects of this Invention being to produce a beautifully mottled
or spotted enamel coat a variant character is given to the same by varying
the temperature at which the drying is accomplished within the range as above
set forth. The higher the temperature the smaller and less distinct the spots;
the lower the temperature the more pronounced the mottlings. The time
required will obviously depend upon the thickness of the enamel coat, and the
quantity of moisture present, and upon the degree of heat employed. When
thoroughly dried the coat is of a whitish colour, and usually either brown spotted,
or reddish-brown spotted, or mottled; and when burned in a muffle is of grayish
colour, dark spotted, or dark and light spotted, or mottled; and the coloring inatter
of these spots or mottles is believed to be a salt or salt of iron produced in a
hydrated form on the surface of the metal during the cleansing processes, the same
being absorbed by or penetrating into the wet enamel coating when dried as herein-
before set forth.
The burning process is effected in an ordinary muffle at a red or cherry-red or
slightly greater heat, the ordinary time required being about four minutes. The
result is a beautifully mottled enamel coat, and one also which adheres to the iron base
with great tenacity; and as to this quality of tenacity, it is found that if out of the
enamel glass the arsenious acid, which as stated is one of the ingredients, is omitted,
the enamel coat resulting from careful following of all the other steps of the
above-described process will not have the adhesive quality necessary for a good
enamel, and as a consequence will be less valuable for the purposes of this In-
vention. And it has been found in practice that a quantity about as specified,
namely, 21 lbs. to 100 lbs. of silica, or to 230 lbs. of all the other ingredients
of the enamel glass gives an enamel of the required quality.
In carrying the above-described process into operation one coat and one burning
are usually found most advantageous.
Having thus fully described the said Invention as communicated to me by my
foreign correspondents, and the manner of performing the same, I wish it under-
stood that I claim,—
First. The enamel glass or crystal composed of silica, borax, soda, plaster of Paris,
and arsenious acid, as and for the purposes set forth.
Second. The combination of clay with the enamel glass or crystal composed of
silica, borax, soda, plaster of Paris, and arsenious acid, as and for the purpose set
forth.
Third. The combination of carbonate of magnesia with the enamel coat composed
of silica, borax, soda, plaster of Paris, arsenious acid, and clay, as and for the purpose
set forth.
Fourth. The employment of sulphate of magnesia in the process of enamelling
sheet-iron ware, as and for the purpose set forth.
Fifth. The employment of arsenious acid in the process of enamelling sheet-iron
ware for the purpose of forming a more tenacious adherence of the enamel on the
iron, as above set forth.
Sixth. The process of enamelling sheet-iron ware, consisting in the making of an
enamel glass or crystal by the complete vitrification of silica, borax, soda, plaster
of Paris, and arsenious acid, the running of the same when so vitrified into water, the
grinding of the same in water with admixture of clay and carbonate of magnesia,
the straining and ripening of the resultant mixture, the treatment of the same
with sulphate of magnesia either in the mixing pan or the mill, or in both, the
coating with the same when thus treated of the annealed and cleansed wrought or

page_text: sheet iron surface, the drying of the coated article, and the burning in the muffle,
all as above set forth.
Seventh. The manufacture of sheet metal mottled enamelled ware whereon the
mottles are developed in the enamel coat by the means above described.
In witness whereof, I, the said William Robert Lake, have hereunto set my
hand and seal, this Seventh day of February, in the year of our Lord
One thousand eight hundred and seventy-eight.
IIM DANT
W. RODT. LAKE.. (L.S.)
M
YY