Tin-plate.
Iron-plate coated with tin by dipping it into a molten bath of the latter metal.
The art of tinning plate-iron seems to have been invented in Bohemia, was carried from thence into
Saxony, 1620, and other parts of
Germany, whence the rest of
Europe was supplied until near the end of the seventeenth century.
The art was introduced into
England by Yarranton about 1675.
The iron used is
charcoal iron, rolled into sheets of various thickness, according to the grade and size of the plates, which are cut into rectangular pieces of the required sizes.
The processes are as follows:—
Scaling. The plate is bent so as to enable it to stand when placed on edge, and is then pickled in a trough containing dilute hydrochloric acid.
The bent plates being laid on the floor in a row, a rod is placed under them, and they are thus lifted and placed in a furnace, where they are heated to redness.
The scale then drops off; after removal and cooling, the plate is beaten smooth on a cast-iron anvil.
Cold rolling between hard, polished rollers confers smoothness and elasticity.
Pickling. The plates are immersed in a bath of acidulated bran-water, at about 100° Fah., for 12 hours, standing half the time on one edge and half on the opposite one.
They are then transferred to a bath of dilute sulphuric acid (100° Fah.), which makes them bright.
This is followed by a bath of clean water and scouring with hemp and sand.
Tinning. The series of pots in which the dipping is performed is placed in a brick structure which rises above the floor of the factory, and at which the workmen stand.
This structure is called the
stow, and contains the furnace which heats the pots.
These cast-iron pots are arranged in a row, and are five in number, — the
tin-pot, wash-pot, grease-pot, pan, and
list-pot.
The
tin-pot contains about 500 pounds of block and grain tin, on which floats 4 inches of tallow, to prevent oxidation.
Alongside it is a grease-pot.
The
wash-pot is nearly full of the best grain-tin, and has a partition to prevent the dross from gathering at that part where the last dip is given to the plates.
The
grease-pot contains lard or tallow free from salt.
The
pan has a grating at bottom, and no fire
under it.
The
list-pot has only 1/4 inch depth of tin in it.
The operation is as follows:—
300 plates previously dipped in a grease-pot are placed one by one in the
tin-pot (No. 1), in a vertical position, and left for an hour or two, the heat being as great as possible without burning the grease.
They are then taken out by tongs and placed on an iron rack to drain.
The plates are then placed in the larger division of the
washpot (No. 2), which melts off the superfluous tin acquired in No. 1; being taken out, a few at a time, from No. 2, they are taken up singly by a pair of tongs, swept on each side by a hempen brush, to make the layer equable and remove drip, and receive a final dip in the clean side of the
wash-pot, by which the marks of the brush are erased.
Each plate, after its final dip in metallic bath, is plunged in the
grease-pot (No. 3), which is so hot as to remove superfluous metal, allowing it to drain off and collect in the bottom of the pot. The plates stand singly in the grease-pot, being separated by pins, and as the pot holds but five, a boy is continually removing the one which has been longest in the grease.
As the boy takes the plates from the
grease-pot (No. 3), he places them on edge in the cold pans (No. 4) to drain off the grease and cool.
The
list-pot (No. 5) is employed for melting off the
list or selvage of tin which has accumulated at the edge of each plate as it stood vertically in the
wash-pot and
grease-pot (Nos.
2 and 3). The
list, being thus melted, is detached by a smart tap with a stick.
The grease is cleaned from the warm plates by rubbing with dry bran.
The plates are then boxed.
Trade custom has prescribed the grades, weights, and sizes, which are indicated by certain marks on the boxes, as shown in the following table:—
| Names. | Sizes. | No.
in a Box. | Weight in a Box. | Box-Marks. |
| Inches. | | Pounds. |
| Common, No. 1 | 13 3/4 × 10 | 225 | 112 | CI |
| Common, No. 2 | 13 1/4 × 9 1/4 | 225 | 105 | CII |
| Common, No. 3 | 12 3/4 × 9 1/2 | 225 | 100 | CIII |
| Cross, No. 1 | 13 1/4 × 10 | 225 | 140 | XI |
| Two cross, No. 1 | 13 1/4 × 10 | 225 | 161 | XXI |
| Three cross, No. 1 | 13 1/4 × 10 | 225 | 182 | XXXI |
| Four cross, No. 1 | 13 1/4 × 10 | 225 | 203 | XXXXI |
| Common doubles | 16 3/4 × 12 1/4 | 100 | 77 | CD |
| Cross doubles | 16 3/4 × 12 1/4 | 100 | 126 | XD |
| Two-cross doubles | 16 3/4 × 12 1/4 | 100 | 147 | XXD |
| Three-cross doubles | 16 3/4 × 12 1/4 | 100 | 168 | XXXD |
| Four-cross doubles | 16 3/4 × 12 1/4 | 100 | 189 | XXXXD |
| Common small doubles | 15 × 11 | 200 | 168 | CSD |
| Cross small doubles | 15 × 11 | 200 | 189 | XSD |
| Two-cross doubles | 15 × 11 | 200 | 210 | XXSD |
| Three-cross doubles | 15 × 11 | 200 | 231 | XXXSD |
| Four-cross doubles | 15 × 11 | 200 | 252 | XXXXSD |
| Wasters, common, No. 1 | 13 3/4 × 10 | 225 | 112 | WCI |
| Wasters, cross, No. 1 | 13 3/4 × 10 | 225 | 140 | WXI |
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The process in
Pittsburg is as follows:—
The sheets, cut into the desired sizes, are “pickled” by immersion in a bath of dilute sulphuric acid for 10 to 20 minutes. They are then annealed for from 6 to 7 hours; then rolled cold, to give them a surface polish.
This operation hardens the iron, so that the plates are again annealed, with greater care and at a lower temperature, for 6 or 7 hours. The plates are then again pickled in an acid bath for some 10 minutes, to remove the scale of oxide, washed in water to remove the acid, and then plunged for a few moments into a bath of palm-oil or melted tallow.
The plates are then put, 40 or 50 at a time, in a tin bath, where they remain about 15 minutes. On leaving this, the plates are plunged into a second tin bath, on leaving which they have the dross brushed off, and go to the third tin bath; from that they go into a tallow or oil bath, from which they are drawn by passing between rolls, which smooths them.
They are then rubbed with shorts, or bran and leather, to clean them, sorted and boxed, each box of I. C. plate, containing 112 pounds, or 112 plates, the plates having a gage of about No. 30, and weighing one pound each; I. X. brand weighs 140 pounds to the 112 sheets.
