IMPROVEMENTS IN THE MANUFACTURE OF ENAMELLED CAST IRON WARE
Year: 1879

page_text: LETTERS PATENT to Eben Colby Quinby, of St. Louis, Missouri, United States
of America, now residing at Stourport, in the County of Worcester, and Enoch
Baldwin, of the Firm of Baldwin, Son, & Co., of Stourport aforesaid, Iron-
founders, for the Invention of "IMPROVEMENTS IN THE MANUFACTURE OF
ENAMELLED CAST IRON WARE."
PROVISIONAL SPECIFICATION left by the said Eben Colby Quinby and
Enoch Baldwin at the Office of the Commissioners of Patents on the 12th
March 1879.
EBEN COLBY QUINBY, of St. Louis, Missouri, United States of America, now
residing at Stourport, in the County of Worcester, and ENOCH BALDWIN, of the
"IMPROVE-
Firm of Baldwin, Son, & Co., of Stourport aforesaid, Ironfounders.
MENTS IN THE MANUFACTURE OF ENAMELLED CAST IRON WARE."
Our said Invention relates to the enamelling of cast iron by an improved process
whereby we can apply to the interior or other surface of cast iron vessels or utensils
a thin enamel coating or lining which will be stronger and more durable or per-
manent and cheaper than the coating or lining produced on cast iron by any process
heretofore known.
We are aware that the lining or coating of cast iron with a kind of enamel or
porcelain has already been practised; therefore our Invention does not consist in
the combination of such a coating or lining with cast iron irrespective of the
peculiar ingredients employed to form the coating or covering, but the said Inven-
tion consists in the enamelling of cast iron by the peculiar process and composition
whereby we effect results which have not heretofore been practicable.
Furthermore we are aware that various compositions have been employed with
more or less success for the enamelling of wrought iron, but these will not succeed
well with cast iron. After many experiments wherein we have ascertained the
different effects produced by the use of different substances or ingredients and
the necessary
proportions on wrought and cast iron we have discovered
ingredients, and the proportions in which they should be combined to ensure suc-
cess in the enamelling of cast iron, and enable us to produce enamelled cast iron

page_text: ware in a commercially advantageous manner, and we employ for this purpose a
peculiar boro-silicate enamel or glass, that is to say, a composition of borax and
silica, which we will 'hereinafter describe.
In practising our Invention it is indispensable that the surface to be enamelled
or glazed should be clean, therefore after having first annealed the article or vessel
we turn the surface thereof in a lathe in the same manner as such articles are
turned for tinning, that is to say, we find the operation of turning affords the
most advantageous method of obtaining the desired cleanliness of the surface to be
enamelled, but if necessary or desirable we may cleanse the same by other means,
such as pickling and scouring.
After being turned the ware should be well washed, preferably in warm water,
and wiped dry; it is then ready for the application of the enamel or glass
coating.
Our improved composition or enamel is composed of equal parts of refined
borax and silica, the latter preferably in a coarse-grained condition. After the
fusion of these materials, which must be very carefully effected to ensure their
thorough and perfect combination we pour or run the composition into cold water.
The glass or vitreous substance thus-produced is then ground in an ordinary
porcelain mill or other suitable apparatus in water, and during this operation we
add about ten (10) pounds of white clay or kaolin to every one hundred (100)
pounds of the glass. After this mixture, or compound has been ground sufficiently
fine, which will ordinarily be effected in about ten hours, it is drawn off, passed
through a fine sieve, and allowed to settle for about ten or twelve hours, and
the surplus water is then removed from the top. The said compound or com-
position at this stage of the process will be thin and watery, but by the addition
of a small quantity of calcined and ground magnesia it is rendered so thick that it
will not run freely. It will then be ready for application to the surface to be
coated. We prefer however to use for thickening the compound sulphate of
magnesia, as this substance facilitates the formation of spots in the enamel or glaze
when it is applied to the cast iron. And it is a peculiar feature of our Invention
that although previously any spotting or mottling has been considered detrimental
to the cast iron ware we now produce the spotting or mottling of the enamel as a
special result or effect for ornamenting our improved ware. And we take advantage
of the peculiar property or nature whereby it appears that our boro-silicic com-
position acts on the surface of clean cast iron when the wet glaze or enamel is
dried very slowly thereon to effect the formation of the spots, that is to say,-
To ensure the desired spotting or mottling of the ware we apply after first
cleansing the surface of the cast iron, the aforesaid glaze or enamel to the said
surface, and then allow the same to dry very slowly. We make the same orna-
mental by tinting or coloring the glaze with such well known ingredients as oxide
of tin, bone-ash, or phosphate of lime, fluor-spar, magnesia, cobalt, oxide of
manganese, oxide of iron, baryta, sulphate of lime, or plaster of Paris and other
suitable substances. The oxides of lead, antimony, and arsenic might also serve,
but we do not consider them safe to use for culinary purposes. The use and choice
of these coloring matters must be left to the judgment of the manufacturer, who,
knowing the result he wishes to produce, can vary his composition accordingly.
It is obviously impracticable to give herein the precise ingredients for all circum-
stances or cases, but it is necessary to state that when oxide of tin or other
ingredients which are not of themselves fluxes or will not act as fluxes are used, a
small portion (ordinarily not exceeding twenty pounds) of the best quality of
carbonate of soda must be added to each one hundred pounds of borax and silica;
care must be taken however not to use too large a quantity of this substance
otherwise few spots will appear, and the enamel will be apt to exfoliate under the
effects of atmospheric changes and become useless. If we wish to avoid the forma-
tion of spots on the enamelled surface we apply the enamel in a very thin coat, and
dry the same quickly thereby not allowing time for the oxidation of the iron

page_text: surface. The slow drying allows the application of a thicker or more perfect coat
as it permits the enamel to "set" or enter the pores of the iron.
The said enamel or glaze is applied to the iron surface of any vessel or utensil
to be coated or lined by pouring a small quantity of the liquid enamel into the said
vessel or útensil, and turning the same around to cause the enamel to cover all
parts of the surface thereof, then pouring out the surplus enamel. Or the said
enamel may be applied by dipping or immersing the vessel or utensil in it or by
other suitable means. After the coating has been applied to it the vessel is dried.
slowly and then burned or fused in an ordinary muffle at a cherry red heat or
slightly below a white heat.
SPECIFICATION in pursuance of the conditions of the Letters Patent filed by the
said Eben Colby Quinby and Enoch Baldwin in the Great Seal Patent Office
on the 12th September 1879.
EBEN COLBY QUINBY, of St. Louis, Missouri, United States of America, now
residing at Stourport, in the County of Worcester, and ENOCH BALDWIN, of the
Firm of Baldwin, Son, and Co., of Stourport aforesaid, Ironfounders.
MENTS IN THE MANUFACTURE OF ENAMELLED CAST-IRON WARE."
" IMPROVE-
Our said Invention relates to the enamelling of cast iron by an improved process
whereby we can apply to the interior or other surface of cast iron vessels or utensils
a thin enamel coating or lining which will be stronger and more durable or per-
manent and cheaper than the coating or lining produced on cast iron by any process.
heretofore known.
We are aware that the lining or coating of cast iron with a kind of enamel or
porcelain has already been practised, therefore our Invention does not consist in
the combination of such a coating or lining with cast iron irrespective of the
peculiar ingredients employed to form the coating or covering, but the said Inven-
tion consists in the enamelling of cast iron by the peculiar process and composition
whereby we effect results which have not heretofore been practicable.
Furthermore we are aware that various compositions have been employed with
more or less success for the enamelling of wrought iron, but these will not succeed
well with cast iron. After many experiments wherein we have ascertained the
different effects produced by the use of different substances or ingredients and
proportions on wrought and cast iron we have discovered the necessary ingredients
and the proportions in which they should be combined to ensure success in the
enamelling of cast iron, and enable us to produce enamelled cast iron ware in a
commercially advantageous manner, and we employ for this purpose a peculiar
boro-silicate enamel or glass, that is to say, a composition of borax and silica,
which we will hereinafter describe.
}
In practising our Invention it is indispensable that the surface to be enamelled

page_text: or glazed should be clean; therefore after having first annealed the article or vessel
we turn the surface thereof in a lathe in the same manner as such articles are
turned for tinning, that is to say, we find the operation of turning affords the most
advantageous method of obtaining the desired cleanliness of the surface to be
enamelled, but if necessary or desirable we may cleanse the same by other means,
such as pickling and scouring.
After being turned the ware should be well washed, preferably in warm water,
and wiped dry, it is then ready for the application of the enamel or glass
coating.
small
Our improved composition or enamel is composed of equal or about equal parts
of refined borax and silica, the latter preferably, in a coarse-grained condition.
After the fusion of these materials, which must be very carefully effected to ensure
their thorough and perfect combination we pour or run the composition into cold
water. The glass or vitreous substance thus produced is then ground in an
ordinary porcelain mill or other suitable apparatus in water, and during this opera-
tion we add about ten (10) pounds of white clay or kaolin to every one hundred (100)
pounds of the glass. After this mixture or compound has been ground sufficiently
fine, which will ordinarily be effected in about ten hours, it is drawn off, passed
through a fine sieve, and allowed to settle for about ten or twelve hours, and the
surplus water is then removed from the top. The said compound or composition
at this stage of the process will be thin and watery, but by the addition of
quantity of pure calcined and ground magnesia it is rendered so thick that it will
not run freely. It will then be ready for application to the surface to be coated.
We prefer however to use for thickening the compound sulphate of magnesia as
this substance facilitates the formation of spots in the enamel or glaze when it is
applied to the cast iron. And it is a peculiar feature of our Invention that although
previously any spotting or mottling has been considered detrimental to the cast
iron ware we now produce the spotting or mottling of the enamel as a special
result or effect for ornamenting our improved ware. And we take advantage of the
peculiar property or nature whereby it appears that our boro-silicic composition
acts on the surface of clean cast iron when the wet glaze or enamel is dried very
slowly thereon to effect the formation of the spots, that is to say :-
To ensure the desired spotting or mottling of the ware we apply, after first cleansing
the surface of the cast iron, the aforesaid glaze or enamel to the said surface, and
then allow the same to dry very slowly. We make the same ornamental by
tinting or coloring the glaze with such well known ingredients as oxide of tin,
bone-ash, or phosphate of lime, fluor-spar, magnesia, cobalt, oxide of manganese,
oxide of iron, baryta, sulphate of lime, or plaster of Paris, and other suitable sub-
stances; the oxides of lead, antimony, and arsenic might also serve, but we do not
consider them safe to use for culinary purposes. The use and choice of these
coloring matters must be left to the judgment of the manufacturer, who, knowing
the result he wishes to produce, can vary his composition accordingly. It is
obviously impracticable to give herein the precise ingredients for all circumstances
or cases, but it is necessary to state that when oxide of tin or other ingredients
which are not of themselves fluxes, or will not act as fluxes, are used, a small
portion (ordinarily not exceeding twenty pounds) of the best quality of carbonate
of soda must be added to each one hundred pounds of borax and silica; care must
be taken however not to use too large a quantity of this substance otherwise few
spots will appear, and the enamel will be apt to exfoliate under the effects of
atmospheric changes and become useless. If we wish to avoid the formation of
spots on the enamelled surface we apply the enamel in a very thin coat, and dry
the same quickly, thereby not allowing time for the oxidation of the iron surface.
The slow drying allows the application of a thicker or more perfect coat as it
permits the enamel to "set" or enter the pores of the iron.
The said enamel or glaze is applied to the iron surface of any vessel or utensil to
be coated or lined by pouring a small quantity of the liquid enamel into the said
vessel or utensil, and turning the same around to cause the enamel to cover all

page_text: parts of the surface thereof; then pouring out the surplus enamel. Or the said
enamel may be applied by dipping or immersing the vessel or utensil in it or by
other suitable means. After the coating has been applied to it the vessel is dried
slowly, and then burned or fused in an ordinary muffle at a cherry red heat or
slightly below a white heat.
Having thus fully described our said Invention, and the manner of performing
the same, we wish it clearly understood that our Invention is distinguished broadly
from any process in which the production or formation of a few spots on the
surface of the enamel coating may take place accidentally, or undesignedly, or
occasionally, for as above stated in our improved manufacture we desire and ensure
the production of spots or mottling on cast iron ware as an ornamental feature, and
because by our process this appearance can be produced with a thinner coat of
enamel than any previously introduced, and we claim,-
The improved manufacture of enamelled cast-iron ware (more or less mottled
or spotted as desired) by the application to the clean surface of the cast iron of the
above described composition or glass consisting of borax and silica in equal
or about equal proportions, and more or less of the other above named ingredients
as above set forth.
In witness whereof, we, the said Eben Colby Quinby and Enoch Baldwin,
have hereunto set our hands and seals, this Tenth day of September, in
the year of our Lord One thousand eight hundred and seventy nine.