Improvements in the Manufacture of Polished Sheet Iron.
Year: 1886

page_text: .
Improvements in the Manufacture of Polished Sheet Iron.
T
I, ISAAC EDWIN CRAIG, residing at Camden, in the County of Preble, State of
Ohio, in the United States of America, Lawyer, 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:-
8.
f. I.
Vic
As uniformly practiced, polished sheet-iron is manufactured from sheets or slabs.
having at some stage, near, which the process, or, operation, of, polishing-is-begun
little or, no,oxide on their surfaces and they are cleansed of their oxide either, by
dissolving, away, the oxide, in, baths of suitable acids, or by restoring the oxide to
metallic condition by heating for a considerable time in packs with layers of
charcoal between them;
الله :
This invention is useful where either method of cleaning is resorted toy
I have discovered that when oxide of lead or a salt of lead or oxide of stin or. a
salt of tin is applied in, small quantities to the surface, of, sheet or, slab, iron and
exposed to a red heat, if graphite, be, also, present in contact with the oxide, or, salt
or in, contact with the metallic lead or tin resulting from the decomposition of the
oxide or, salt, that the lead or tin in the state of metal unites by chemical action or
mechanical mixture with the graphite, and forms on the surface of the sheets, or
slabs a coating which possesses some of the properties of both the metals and the
graphite, but,, unlike graphite, is fusible, and will not rub off, and, unlike the metal
has some capacity for a durable luster; and that in the subsequent working of the
sheets at a heat while being polislied the metals and graphite become, mingled and
incorporated with the new oxide on the surface of the sheets in such a way as to
give to the surface a close texture, ability to resist corrosion, and, a handsome
appearance. The presence of this, mixture on the surface of the sheets prevents the
developement in finishing of red or brown,spots or patches, which are a source of
much, loss, in the manufacture of polished, sheets. It is already known that an
improvement is made in the quality of the surface, of polished sheet iron by
applying, during its, manufacture, to the, sheets or slabs a small quantity of oxide
of lead or oxide of tin,.so that on being reduced their metals may unite with the
surface, & produce, as they are found to do, a desirable tenacity and flexibility of
oxide on the finished, sheets.
"
021 91.
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It is also known that an improvement results from the presence on the sheets
during the latter, steps of their, manufacture, of a small quantity of, graphite, &
that graphite so used gives adaptability to polish, uniformity of color, and chemical
[Pring Bd11

page_text: inertness to the surfaces so produced. But the qualities resulting from these two
methods of treatment have not heretofore been obtained on the same sheets, &
I find in practice that where lead or lead and tin are revived on the sheets from
the oxide or salts, in the after working of the sheets without the presence of
graphite a part of the lead on a majority of the sheets reoxidizes and fuses into
the well known red, glassy, brittle form of fused litharge & of the remainder of the
soft metals not so reoxidized a part is gathered into grains or specks on the
surfaces in finishing. I also find that where graphite is used, although favoring in
the highest degree the acquisition of luster, without the presence of lead or tin, the
surface produced lacks flexibility & attachment to the body of the iron on being
bent. And I further find that graphite unlike other forms of carbon does not act
as a reagent to reduce the metallic oxides, as its lowest temperature of combustion
is much above the highest heat used in making sheet iron, but that it remains
forming chemical union or mechanical mixture with the revived metals and the
• surface of the iron, and that the oxides are reduced by the hydrogen occluded
within the iron or by the hydrocarbons in the heated atmosphere of the furnace;
and that this reduction is accomplished as well when the coating of oxides and
graphite is a mixture of these solids with water as when oil or other carbonaceous
matter is used.
I also find that the several defects as above described attending the separate use
of the materials named disappear when the materials named are jointly used.
The object of this invention is to produce all these beneficial effects on the same
sheets by the application of the materials above named; and to this end my
invention consists in the following treatment of the sheets or sheet slabs which
have been cleansed of their coating by any of the means known to the art.
(6
I prepare a mixture of oxide of lead or salts of lead and graphite, or the oxide or
salt of tin and graphite, or of all three, using by preference, and as I think best for
use on slabs, four pounds of oxide of lead, litharge rather than red lead, one
quarter pound of oxide of tin, known as putty powder" or "polishing powder,"
and one pound of graphite, ground together in one gallon of any suitable fluid, by
preference, linseed oil, and apply this by a wide brush or other convenient means
to the surfaces of each sheet or slab to be operated on.
In those cases where in the process of manufacture the iron is cleaned in sheet
slabs and the oxide is removed by acids they should have this 'paint applied to
them before being again heated, and if deoxidized by heating the slabs with inter-
layers of charcoal or other deoxidizing agent the paint should be applied when
they are being piled up for this operation, and before the application of the
charcoal powder, and is not in danger of being removed when the charcoal is
afterward swept away, as it is then firmly attached to the surface. These slabs
should not be more than about three times as thick as the sheets are intended to
be when finished.
The slabs may then be worked down to sheets in the ordinary manner of rolling
at moderate red heat, will roll without sticking one to another, and will acquire
some luster in being so reduced.
They should then be heated and polished in packs in the usual manner under
steam hammers.
When the sheets are cleaned at about the gage at which they are to be finished,
the mixture of graphite, oxide and oil should be made with but one third so much
oxides and graphite to a given quantity of oil as that stated as the correct
proportions for use on slabs and applied in the usual manner, before being piled.
They should, if cleansed with acids, be heated to high redness with the paint on
in the annealing or other convenient furnace in packages, and when withdrawn
opened so as to expose each sheet to the air while red hot to color and reoxidize
the iron; and if at this thickness they are reoxidized with charcoal and heat, the
paint should be first applied, and, when deoxidized, should be swept of their
charcoal while still red hot, so as to give access of air on their surfaces while at a
high temperature.
2

page_text: In either case after having been painted, heated and reoxidized as described,
they are ready to be reheated and polished in packs under the hammer in the
usual manner.
In each of these operations I find it most economical and desirable to apply the
oxides and the graphite at one and the same time and already mixed together;
but I do not confine myself to that method alone, as I find that they may be
applied separately and even with one or more heats of the iron intervening, if
there is a heat and application of mechanical force in rolling or hammering after
the last is applied, and their intermixture and union with the surface in a great
degree still takes place.
Iron so made combines the excellent qualities already described.
Having now particularly described and ascertained the nature of my said
invention, and in what manner the same is to be performed, I declare that what
I claim is
An improvement in the manufacture of sheet iron, consisting of the following
process; cleansing the iron of its coating of oxide by any means known to the art,
then coating the surface before the final heat and working, with a composition of
matter, consisting of graphite and an oxide or salt of, either or both, tin and lead,
then heating and exposing to the air while still hot, and finally polishing by
rolling or hammering in packages, in the usual manner, substantially as specified.
Dated this 10th dor of Nouch 1006