IMPROVEMENTS IN THE MANUFACTURE OF ENAMELLED DIAL AND OTHER PLATES
Year: 1874

page_text: LETTERS PATENT to Joseph Henry Robinson, of Liverpool, in the
County of Lancaster, for the Invention of "IMPROVEMENTS IN THE
MANUFACTURE OF ENAMELLED DIAL AND OTHER PLATES."
Sealed the 19th June 1874, and dated the 18th April 1874.
PROVISIONAL SPECIFICATION left by the said Joseph Henry Robinson
at the Office of the Commissioners of Patents, with his Petition, on
the 18th April 1874.
I, JOSEPH HENRY ROBINSON, of Liverpool, in the County of Lancaster,
do hereby declare the nature of the said Invention for "IMPROVEMENTS
IN THE MANUFACTURE OF ENAMELLED DIAL AND OTHER PLATES," to be as
follows:-
My Invention relates to the manufacture of enamelled iron dials for
gas and water meters, clocks, and other purposes, number, address, and
other plates, labels, or tablets, which I am enabled to produce more
cheaply and quickly than heretofore.

page_text: According to my Invention I make the foundation of the dial or
plate of thin sheet iron, which is stamped out by means of a press and
suitable dies to the size required, with the edges turned up all round so
as to form a kind of shallow tray to hold the enamel. The necessary
screw and spindle holes in the dials or plates are punched out at the
same time, and also have their edges turned up for the same purpose.
The plate having been made chemically clean it is then ready for the
application of an enamel composed of the following ingredients, viz. :—
Whitelead, arsenic, flint glass, saltpetre, borax, and ground flint. These
substances having been all reduced to powder are mixed together and
melted in a crucible. When thoroughly fused together the contents of
the crucible are poured out in the form of cakes, which before cooling
are plunged in cold water to render them brittle. The cakes of enamel
are then pounded in a mortar to the fineness of coarse sand, and the
powdered enamel is then washed, and when dried is ready for use as
follows: A sufficient quantity of the enamel is sprinkled on the plate,
which is then placed in a muffle to fuse the enamel. The raised edges of
the plate retain the enamel, which adheres without the aid of any
adhesive material. When the enamel is fused the plate is withdrawn
from the muffle and allowed to cool. When cold it will have a hard
white glazed surface, and is then ready for receiving the lettering and
figuring, which is applied by printing with soft black enamel from
engraved plates on paper, and then transferring the impression to the
enamelled plate in the ordinary way, after which the plate is replaced
in the muffle to fuze the enamel forming the body of the lettering or
figuring

page_text: seventh year of Her reign, did, for Herself, Her heirs and successors,
give and grant unto me, the said Joseph Henry Robinson, Her special
license that I, the said Joseph Henry Robinson, my executors, admini-
strators, and assigns, or such others as I, the said Joseph Henry
Robinson, my executors, administrators, and assigns, should at any
time agree with, and no others, from time to time and at all times
thereafter during the term therein expressed, 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 ENAMELLED DIAL AND OTHER
PLATES," upon the condition (amongst others) that I, the said Joseph
Henry Robinson, my executors or administrators, by an instrument in
writing under my, or their, or one of their hands and scals, 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 Joseph Henry Robinson, 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 thereof, reference being had to the accom-
panying Drawing and to the letters and figures marked thereon, that is
to say:―
My Invention relates to the manufacture of enamelled iron dials for gas
and water meters, clocks, and other purposes, number plates, address and
other plates, labels, or tablets, which by my Invention I am enabled to
produce more cheaply and quickly than heretofore.
According to my Invention I make the foundation of the dial or plate
of thin sheet iron, which is stamped out by means of a press and suitable
dies of the size and shape required, according to the purpose for which it
is intended, with the edges turned up all round so as to form a kind of
shallow tray to hold the enamel on the face of the plate. The necessary
holes for the passage of the index spindles, in the case of a meter or
clock dial, or for the screws by which it is fixed in position, are punched
at the same time, and also have their edges turned up for the same
purpose.
.
с
The annexed Drawing shows a face view and section of a door plate

page_text: :
a is the sheet metal backing or foundation with turned up edges b; c,
are screw holes, also with turned up edges to hold the enamel d with
which the plate is faced. The plate is preferaby made slightly concave
at back, as shown, to hold a thin coating of coarse enamel e to protect it
from rust. The plate having been made chemically clean by pickling
in acid is then ready for the application of an enamel composed of the
ingredients hereafter mentioned. The proportions given are calculated
by weight. I find these proportions such as answer the purpose, but it
will be understood that I do not confine myself to the precise proportions
named, as such may be varied without departing from my Invention :-
Whitelead, 12 oz.; arsenic, 2½ oz.; flint glass, 8 oz.; saltpetre, 3 oz ;
borax, 6oz.; and ground flint, 2 oz. These substances having been all
reduced to powder are mixed together and melted in a crucible. When
thoroughly fused together the contents of the crucible are poured out in
the form of cakes, which before cooling are plunged in cold water to
render them brittle. The cakes of enamel are then pounded in a mortar
to the fineness of coarse sand, and the pounded enamel is then washed,
and when dried is ready for use as follows:-(If desired to enamel the
back of the plate this is applied before the face is enamelled. For this
purpose the "pulp" obtained from the washings of the enamel is mixed
with powdered glass and sand, and first applied in a liquid state to form
a thin coat on the concave back of the sheet-iron foundation of the dial
or plate, and allowed to dry.) A sufficient quantity of the dry pulverized
enamel is sprinkled on the face of the plate, which is then placed in a
muffle to fuse the enamel, the raised edges of the plate retaining the
enamel, which adheres without the aid of any adhesive material. When
the enamel is fused the plate is withdrawn from the muffle and allowed
to cool, and when cold it will have a hard white glazed surface, and is
then ready for receiving the lettering and figuring. The lettering or
figuring is applied by printing with soft black enamel from engraved
plates, an impression being first taken on paper, and thence transferred
to the enamelled surface of the dial or plate in the ordinary way, after
which the plate is replaced in the muffle to fuze the enamel forming the
body of the lettering or figuring.
The great advantage of my Invention is that the enamelling can be a
performed much more quickly and cheaply in consequence of the enamel
being applied in a dry pulverized state. Morcover the enamel being
applied in a dry state is free from specks and dirt. all the impurities.

page_text: having been washed away, and the iron backing or foundation is much
more durable than those of copper.
Having described the nature of the Invention, and the manner of
performing the same, I declare that what I claim as my Invention to be
protected by the herein-before in part recited Letters Patent is, the
manufacture of enamelled dial and other plates, labels, or tablets of thin
sheet iron, stamped out with turned up edges, and an enamel compo-
sition prepared as herein specified, and applied in a dry coarsely
powdered state without any adhesive material, substantially as set forth.
In witness whereof, I, the said Joseph Henry Robinson, have here-
unto set my hand and scal, this Thirteenth day of October, in
the year of our Lord One thousand eight hundred and seventy-
four.
JOSEPH HENRY ROBINSON. (L.S.)