The Roanoke times. [volume] (Roanoke, Va.) 1890-1895, 1891-03-01
MAKING TIN PLATES.
A Clear and Concise Description
of the Process.

a great deal has beer said in tho
papers OF late about the making of tin
plates in this country, but comparatively
few are acquainted with tho nature of
the manufacture. What is called a ''tin
plate" is mostly iron, or soft steel, with
o very little tin as q covering. The fol-
lowing letter of Mr.. John Jarrett, an
acknowledged expert in tho business,
to b Bulletin of the Iron and Steel
Association, gives a concise and clear
description of the process. 1t will be
seen that labor is the chief item of cost.
Whatever difference of opinion there
may be as to the propriety of in
creased duties being imposed on tin
plate, one business fact remains which
cam OF be ignored-that.gi the same
price for sheet iron or steel in both
England and tho United States, the
higher cost of labor here must prevent
tin plates at the outset from being made
as cheaply here as in Virginia:
With the establishment of tin plate
industries in this country, induced by
the positive protection given for several
years, tho chances are that as in
oSher industries, improvements in
methods and machinery will reduce
the cost of making here. At the same
time there is a growing and ~irresis-
table tendency towards higher wages
in England, which may in time equal
ize tho cost in the two countries.
Evils are not wholly unmixcd with
good, and while tho cost of tin plates
In this country may be temporarily
may be one very decided advan-
tage resulting from tho building up
OF tin plate industries here. namely,
tho avoidance of q combination of for
elgn makers to put up prices. A COM
parat1vcly few men control the mar
ket in Great Britain, and it is q fairly
easy thing for them at any moment to
combine, and make tho outside world
pay just what they see fit to demand.
HOW TINpLATEs ARE MADE IN GREAT
BRITAIN
Charcoal iron is no longer used in the
manufacture of tinplatcs, and the
quantity of puddled bars now used for
this purpose is also very limited. The
bulk of the finer and better qualities of
plates is now made of ~open-hearth steel,
and nearly all tho cheaper grades arc
made of low-carbon Bessemer steel. We
will, therefore, deal only with our sub
ject from the bars of iron or steel
(Which in mills arc generally called
uh DdrS 10 Iue HnlSnoQ plates.
In the first place wo have the bar, de-
llvered from tho bar mill, several feet
long, about seven inches wide, and from
one-half to hve-eighths of an inch thick,
rolled according to tho size of the
plates required at so many pounds per
foot. The bar is taken and shcared
into tho required lengths, say about Is
inches, which would weigh about 10
pounds to the piece. This would be the
length of a bar required to produce
sheets Ia inches by 90 inches in size.
The bar would eventually be rolled into
16 sheets of this size, 112 of such sheets
forming a box Inc Weighing when
timed about 1OS pounds.
This piece of bar iron, fifteen inches
long, is placed in a reverberatory fur
mace, heated to redness, put through the
chilled rolls, and rolled into what is
termed "thick." 1t is then relocated and
rolled in ''singles" until reduced in
thickness so as to be easily doubled,
after which it is doubled, relocated, and
rolled, three times in succession. BY
this time it will be seen that the nine
teen pound bar is eight shoots in thick
ness. In this shape it is rolled until
each sheet is reduced to the required
length and thickness. The whole mass
IS next taken and sheared into two parts
and the rough edges taken off. We have
then eight sheets in each part adhering
very closely together. Girls arc gener-
ally employed to open or separate these
packs" as they are called, which they
do with small hatchets, protecting their
hands with hand-leathers. The plates
are now termed "black plates"
The plates are next sent to be picked
that is, immersed in heated dilute
s%ulphuric acid. This process is now
generally done by the aid of patent
picking machines, among which are
H~utching's, Morris's, Lewis's, and
Hyde's. The plates are placed in a
cradle or receptacle, which is lifted by
hydraulic power and lowered into a
tank containing the acid. The cradle
is then given a revolving or other
motion to make the liquid rush between
the sheets After being subjected to
the action of the acid for some time the
cradle is again lifted by hydraulic
power and dropped into another tank
containing an ample supply of clean
water only, the cradle revolving as in
the acid tank. SO that the water nav
rush between the sheets and wash away
all traces of the acid. When taken out
the plates are bright and clean. Thew
are then placed in closed iron annealin1
pots and subjected to a bright-red heat
In an annealing furnace for from twelve
to twenty-four hours.
The next process is to pass the plates
through cold rolls three, four. or moro
times, as may be deemed necessnrv.
This is called cold rolling. These rolls
are highly polished, and must be set
very accurately in order to give the
plates 4 perfectly fiat set and a we'll
pollshed surface. After this rollinu thn