Improvements in the Manufacture of Enamelled Metallic Ware.
Year: 1896

page_text: Date of Application, 21st July, 1896-Accepted, 5th Sept., 1896
COMPLETE SPECIFICATION.
Improvements in the Manufacture of Enamelled Metallic Ware.
I, ALEXANDER NIEDRINGHAUS, of No. 304, North Eighth Street, in the
City of St. Louis, State of Missouri, United States of America, Gentleman, 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 and useful improvement in the manufacture of
enamelled ware, and cousists essentially in the method of treating the base, or the
part which is to be enamelled.
Heretofore, in the manufacture of enamelled ware, iron has generally been used
as a base. Steel has been used to a greater or less extent for some wares, but
with the result, generally, that pin holes, flecks, and chips, occur to such an extent
as to constitute a serious objection to its use, destroying the beauty and impairing
the usefulness of the enamelled ware. Pin holes, as they are called, appear
irregularly over the enamelled surface, and are the result of the development of a
gas or gases beneath the enamel coating, during the fusion of the glaze, forming
bubbles, which, bursting, expose the black metal beneath. Flecks, as they are
called, also appear irregularly over the enameled surface, but are apparently
produced by different or modified causes from that ascribed to pin holes. These
Hecks, or scale-like chips, differ in depth and size. Some of them extend down to,
and expose the surface of the base, while others are more shallow, and show the
dark color of the glaze near the base. In many instances, the enamel is not
entirely flecked off, but is loosely attached, appearing white where the rupture of
the fleck extends beneath the surface of the enamel. Moreover, it is known that
these fleckings occur after the ware has been removed from the muffle, and it may
be some time before they appear. Chips, or chippings, as they are called, are
generally found at corners of the ware and expose the surface of the base to a
considerable extent. This is supposed to be the result of insufficient attachment of
the enamel to the base, aggravated by the strain of gases in some cases, causing it
to flake or chip off in large pieces and expose the base.
I am aware that colored enamel consisting of two or more coats, has been applied
to steel. This is accomplished by burning the first coat, which is usually colored
with cobalt or manganese, into the steel under excessive heat. If any of the defects
to which I have heretofore referred, are present in this first coat, they do not
constitute a serious objection, because they are cured or covered by the second
coat of soft and easy fusing glaze, which is generally opaque so as to hide the
first coat.
I will now describe iny invention, and, in the beginning, desire to be understood
as not limiting myself to the exact ingredients herein named, the proportion of
such ingredients, as I have found by experiment, desirable to use, nor the particular
manuer herein described of using the ingredients, as it is obvious that there are
many equivalents which could be employed with more or less success.
To begin with, in the manufacture of mottled enamelled ware having steel for
its base, the same general steps are employed to convert the raw material into a
finished article, with such exceptions as I will note, as are employed in making
nottled enamelled ware with iron for its base.
The base, either steel or iron, having been rolled into sheets, is stamped or
seamed into form, and enamelled.

page_text: This invention is based upon the discovery that sulphur, incorporated into the
base, either during the manufacture of the metal base, or while the base is being
annealed, causes the metal to be particularly well adapted to the reception of a
perfect glaze of mottled or variegated enamel, or in fact of any well-known or
suitable enamel. It has been found, by experiment, that from 12 to 20 per cent.
of sulphur in the steel or homogeneous iron gives excellent results, but of course,
it is understood that this percentage could be changed to suit different conditions.
In carrying my invention into effect, I may either anneal the steel in the
presence of sulpbur, or I may incorporate the sulphur into the steel or homogeneous
iron at the time of its manufacture, as above stated.
In annealing the steel or homogeneous iron base in the presence of sulphur,
I introduce the sulphur into the annealing pot, preferably in the first annealing, as
it is known in the art, and in about the proportion of two pounds of sulphur to one
hundred pounds of steel, and subject the same to proper annealing heat, which
generally takes from three to six hours.
It has been found that this sulphur treatment of the base, has the peculiar effect
of preventing the production of bubbles, pin holes, flecks, and scale-like chips,
above described, which treatment also enables the base to receive a coat of enamel
which firmly and uniformly adheres thereto, thus producing a superior article of
enamelled ware. By this sulphur treatment the steel is also rendered more
sensitive to receive the enamel by being more thoroughly etched.
Instead of adding the sulphur in the first annealing, as hereinabove described,
it may be introduced into the annealing pot after the metal has been shaped into
form of ware, that is to say, the ware having been stamped out, or shaped, is put
into the annealing pot and the sulphur introduced in about the proportions above
set forth. The annealing pot is then closed and heat applied for from three to six
hours until the sulphurous fumes shall have become thoroughly incorporated with
the metal base, after which the metal base thus treated can be subjected to the
enamelling process with the beneficial results hereinabove indicated.
It has been found that if chloride of calcium in the proportion of about three-
fourths of a pound of said chloride of calcium to one hundred pounds of steel, be
added to the sulphur in the annealing pot, the satisfactory results hereinabove
indicated will also follow, and that, if, instead of chloride of calcium, other
chlorides, a salt of ammonia, or nitre, be used in conjunction with the sulphur, like
results will be produced. Hence, this invention which, broadly considered, consists
in the incorporation of the sulphur in about the proportions indicated, with the
metal base, will not be avoiding by adding to the sulphur either the chloride of
calcium or analogous substance.
Having now particularly described and ascertained the nature of my said inven-
tion, and in what manner the same is to be performed, I declare that what I
claim is :
1. The process herein described of preparing steel for enamelling, which consists
in combining it, in the presence of heat, with sulphur; substantially as described.
2. The process herein described of preparing steel for enamelling, which consists
in subjecting the steel to the action of sulphur before it is coated with the enamel;
substantially as described.
3. The herein described process of preparing steel for enamelling, which consists
in annealing the same in the presence of a chloride and sulphur; substantially as
described.
4. The herein described process of making enamelled ware, which consists in
first charging the steel with sulphur and in then applying the enamel thereto and
fusing the same thereon; substantially as described.
5. The herein described process of preparing steel for enamelling, consisting in
impregnating the same with elements which destroy the effect of gases injurious to.
the enamel; substantially as described.
6. The herein described process of preparing steel for enamelling, which consists

page_text: in rendering the steel insensible to gases injurious to the enamel, which treatment
also has a physical effect upon the steel, rendering its surface capable of effecting
an intimate adhesion of the enamel; substantially as described.
Dated the 21st day of July 1896.
PHILIP M. JUSTICE,
Chartered Patent Agent, London,
For the Applicant.