Middletown transcript., 1883-02-23
HOW TIN PLATES ARE MADE.

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employed in the manufacture of thisuse-
full article
The British have recently visited the
Dyferyn Iron and Tin Plate Works at
Swansea, situated on the river Tawe,
with view of informing themselves
regarding the practical workings of this
important industry. The same asso-
citation met at Swansea % years ago,
since which time great advances have
been made in the processes of manu-
facture. From the forty mills now
running within a radius of three miles
in the Swansea valley, about 10000
boxes of finished tin plate are turned
out weekly, or /, 900, 900 boxes annually,
which is estimated to be equal to about
one-third Of the entire export.
But how tin plates are made is .infor-
nation likely to interest most readers !:
In the first place, says the writer, we
have what is termed bar iron, several
feet long, and about inches wide, and
from ] to 5 of an inch in thickness,
rolled according to the plates required
at so many pounds per foot. 1t is cut
in what may be termed jack-in-the-
box OF steam shear, say about 10
pounds to a piece which will eventually
be rolled into 16 sheets Of 20 inches
long by IA inches wide, liz of such
sheets forming a box, and weighing
when timed nearly cwt.
The piece of iron is first placed in a
reverberatory furnace, heated to red
ness, put through the chilled rolls, and
rolled in what is termed thick, five
times reheated and. rolled in singles
twice; doubled, reheated and rolled
three times doubled, reheated and
rolled twice; doubled, reheated and
rolled in eights, twice, until they are
stretched out to the required thickness.
The length of the bar exceeds by about
one inch the width of the sheet to be
made, so as to allow for the shearing
process, and the bar is therefore rolled
with its axis parallel to that of the
rolls. Great attention is necessary in
the construction and management of
the mill furnaces, so that the heating
of the bar and sheets for rolling may
be effected with the utmost regularity,
and without the formation of scale on
the surface of the bars or sheets for
when sealing takes place from the
draught in the furnace being too keen
or the heat raised too high, the quality
of the iron is injured the scale, if sub
sequently rolled into the iron, leaves
rough surface on the plates in the after
process Of separating and picking. The
plates are then sheared, and the rough
edges taken off. The iron Of 10 pounds
or thereabouts makes 16 sheets which,
being cut in half, leaves s sheets in a
piece closely wedged. Girls with small
iron hatchets open them. They are
then termed black-plate. From one
ton Of bar iron about 162 cwt. of black
plate is made the loss is termed shear
ings, and is worked up again in the
forge-fneries. The plates are next sent
so be picked, l. e., immersed in heated
dilute sulphuric acid, known as oil of
vitrol.
This process is done by the aid of a
patent, known as Hutchings' patent
picking machine. The plates are
placed in brass cradle OF receptacle,
lifted by hydraulic, then dropped down
into a round wooden OF lead tank con-
tanning the 0. V. the cradle is then
made to revolve by means Of steam
power, to enable the liquid to rush be-
tween the sheets, which revolution is
retained. They are lifted again by the
hydraulic, and dropped into a tub a
little apart from the last, containing
water only, the cradle revolving as in
last tub, so that the water may rush
between the sheets to cleanse or wash
away all traces of the acid, when taken
up again the plates are clean and
bright as silver. They are next sub
jected to bright red heat, which lasts
from 12 to "a hours, in closed iron an
nealing pots i'll a reverberatory furnace;
they are well covered on the top to pre-
vent the plates from being burnt the
heat is kept as high as it can be with
out softening them to such degree as
to cause them to stick fast together
and prevent their separation when
cold.
They next pass simply through cold
rolls, three, four or more times, as may
be deemed requisite. These rolls are
highly polished, and must be set in ac-
curate order to give the plates a per-
fectly fiat set and well polished surface.
Again they are annealed or softened at
lower temperature than the first, as
their surfaces would be damaged by be-
ing in any degree stuck together.
Picked again as before, excepting that
the liquid is considerable weaker than
previously, placed in cast iron troughs
containing clean water renewed by a
stream constantly flowing through, they
are then taken in hand singIy, and
secured if necessary with sand and
hempen pads before being delivered to
the tinman.
Now comes the last process. The
sheets are iron only so far. They next
reach the tin house, and are placed in
trough containing clean water, ready
for the tinman, as he is termed, who
then picks them up and puts them
singly in a grease pan containing palm
oil, to soak, and after being there for
short time the tinman places the sheets
in large iron pot containing molten
tin, with a covering Of palm OIL Here
it unites with the tin, to which it has
a strong affinity. When he has