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Manufacturing

On Over Manufacturing
284. One of the natural and almost inevitable consequences of...

Economy Of The Materials Employed
77. The precision with which all operations by machinery are ...

On The Future Prospects Of Manufactures As Connected With Science
453. In reviewing the various processes offered as illustrat...

Of Copying By Stamping
128. This mode of copying is extensively employed in the art...

Of Raw Materials
210. Although the cost of any article may be reduced in its ...

Of Copying By Moulding
112. This method of producing multitudes of individuals havi...

Of Copying By Casting
105. The art of casting, by pouring substances in a fluid st...

Distinction Between Making And Manufacturing
163. The economical principles which regulate the application...

Enquiries Previous To Commencing Any Manufactory
298. There are many enquiries which ought always to be made ...

Of Price As Measured By Money
201. The money price at which an article sells furnishes us ...

On A New System Of Manufacturing
305. A most erroneous and unfortunate opinion prevails among...

On Combinations Amongst Masters Or Workmen Against Each Other
353. There exist amongst the workmen of almost all classes, ...

Accumulating Power
20. Whenever the work to be done requires more force for its ...

Increase And Diminution Of Velocity
32. The fatigue produced on the muscles of the human frame d...

On The Exportation Of Machinery
437. A few years only have elapsed, since our workmen were n...

On The Division Of Labour
241. We have already mentioned what may, perhaps, appear par...

Registering Operations
65. One great advantage which we may derive from machinery is...

Saving Time In Natural Operations
47. The process of tanning will furnish us with a striking i...

Proper Circumstances For The Application Of Machinery
329. The first object of machinery, the chief cause of its e...

Of Money As A Medium Of Exchange
166. In the earlier stages of societies the interchange of t...



Printing From Surface








91. This second department of printing is of more frequent
application in the arts than that which has just been considered.

92. Printing from wooden blocks. A block of box wood is, in
this instance, the substance out of which the pattern is formed:
the design being sketched upon it, the workman cuts away with
sharp tools every part except the lines to be represented in the
impression. This is exactly the reverse of the process of
engraving on copper, in which every line to be represented is cut
away. The ink, instead of filling the cavities cut in the wood,
is spread upon the surface which remains, and is thence
transferred to the paper.

93. Printing from moveable types. This is the most important
in its influence of all the arts of copying. It possesses a
singular peculiarity, in the immense subdivision of the parts
that form the pattern. After that pattern has furnished thousands
of copies, the same individual elements may be arranged again and
again in other forms, and thus supply multitudes of originals,
from each of which thousands of their copied impressions may
flow. It also possesses this advantage, that woodcuts may be used
along with the letterpress, and impressions taken from both at
the same operation.

94. Printing from stereotype. This mode of producing copies
is very similar to the preceding. There are two modes by which
stereotype plates are produced. In that most generally adopted a
mould is taken in plaster from the moveable types, and in this
the stereotype plate is cast. Another method has been employed in
France: instead of composing the work in moveable type, it was
set up in moveable copper matrices; each matrix being in fact a
piece of copper of the same size as the type, and having the
impression of the letter sunk into its surface instead of
projecting in relief. A stereotype plate may, it is evident, be
obtained at once from this arrangement of matrices. The objection
to the plan is the great expense of keeping so large a collection
of matrices.

As the original composition does not readily admit of change,
stereotype plates can only be applied with advantage to cases
where an extraordinary number of copies are demanded, or where
the work consists of figures, and it is of great importance to
ensure accuracy. Trifling alterations may, however, be made in it
from time to time; and thus mathematical tables may, by the
gradual extirpation of error, at last become perfect. This mode
of producing copies possesses, in common with that by moveable
types, the advantage of admitting the use of woodcuts: the copy
of the woodcut in the stereotype plate being equally perfect.
with that of the moveable type. This union is of considerable
importance, and cannot be accomplished with engravings on copper.

95. Lettering books. The gilt letters on the backs of books
are formed by placing a piece of gold leaf upon the leather, and
pressing upon it brass letters previously heated: these cause the
gold immediately under them to adhere to the leather, whilst the
rest of the metal is easily brushed away. When a great number of
copies of the same volume are to be lettered, it is found to be
cheaper to have a brass pattern cut with the whole of the proper
title: this is placed in a press, and being kept hot, the covers,
each having a small bit of leaf-gold placed in the proper
position, are successively brought under the brass, and stamped.
The lettering at the back of the volume in the reader's hand was
executed in this manner.

96. Calico printing from blocks. This is a mode of copying,
by surface printing, from the ends of small pieces of copper
wire, of various forms, fixed into a block of wood. They are all
of one uniform height, about the eighth part of an inch above the
surface of the wood, and are arranged by the maker into any
required pattern. If the block be placed upon a piece of fine
woollen cloth, on which ink of any colour has been uniformly
spread, the projecting copper wires receive a portion, which they
give up when applied to the calico to be printed. By the former
method of printing on calico, only one colour could be used; but
by this plan, after the flower of a rose, for example, has been
printed with one set of blocks, the leaves may be printed of
another colour by a different set.

97. Printing oilcloth. After the canvas, which forms the
basis of oilcloth, has been covered with paint of one uniform
tint, the remainder of the processes which it passes through, are
a series of copyings by surface printing, from patterns formed
upon wooden blocks very similar to those employed by the calico
printer. Each colour requiring a distinct set of blocks, those
oilcloths with the greatest variety of colours are most
expensive.

There are several other varieties of printing which we shall
briefly notice as arts of copying; which, although not strictly
surface printing, yet are more allied to it than that from
copperplates.

98. Letter copying. In one of the modes of performing this
process, a sheet of very thin paper is damped, and placed upon
the writing to be copied. The two papers are then passed through
a rolling press, and a portion of the ink from one paper is
transferred to the other. The writing is, of course, reversed by
this process; but the paper to which it is transferred being
thin, the characters are seen through it on the other side, in
their proper position. Another common mode of copying letters is
by placing a sheet of paper covered on both sides with a
substance prepared from lamp-black, between a sheet of thin paper
and the paper on which the letter to be despatched is to be
written. If the upper or thin sheet be written upon with any hard
pointed substance, the word written with this style will be
impressed from the black paper upon both those adjoining it. The
translucency of the upper sheet, which is retained by the writer,
is in this instance necessary to render legible the writing which
is on the back of the paper. Both these arts are very limited in
their extent, the former affording two or three, the latter from
two to perhaps ten or fifteen copies at the same time.

99. Printing on china. This is an art of copying which is
carried to a very great extent. As the surfaces to which the
impression is to be conveyed are often curved, and sometimes even
fluted, the ink, or paint, is first transferred from the copper
to some flexible substance, such as paper, or an elastic compound
of glue and treacle. It is almost immediately conveyed from this
to the unbaked biscuit, to which it more readily adheres.

100. Lithographic printing. This is another mode of producing
copies in almost unlimited number. The original which supplies
the copies is a drawing made on a stone of a slightly porous
nature, the ink employed for tracing it is made of such greasy
materials that when water is poured over the stone it shall not
wet the lines of the drawing. When a roller covered with printing
ink, which is of an oily nature, is passed over the stone
previously wetted, the water prevents this ink from adhering to
the uncovered portions; whilst the ink used in the drawing is of
such a nature that the printing ink adheres to it. In this state,
if a sheet of paper be placed upon the stone, and then passed
under a press, the printing ink will be transferred to the paper,
leaving the ink used in the drawing still adhering to the stone.

101. There is one application of lithographic printing which
does not appear to have received sufficient attention, and
perhaps further experiments are necessary to bring it to
perfection. It is the reprinting of works which have just arrived
from other countries. A few years ago one of the Paris newspapers
was reprinted at Brussels as soon as it arrived by means of
lithography. Whilst the ink is yet fresh, this may easily be
accomplished: it is only necessary to place one copy of the
newspaper on a lithographic stone; and by means of great pressure
applied to it in a rolling press, a sufficient quantity of the
printing ink will be transferred to the stone. By similar means,
the other side of the newspaper may be copied on another stone,
and these stones will then furnish impressions in the usual way.
If printing from stone could be reduced to the same price per
thousand as that from moveable types, this process might be
adopted with great advantage for the supply of works for the use
of distant countries possessing the same language. For a single
copy might be printed off with transfer ink, and thus an English
work, for example, might be published in America from stone,
whilst the original, printed from moveable types, made its
appearance on the same day in England.

102. It is much to be wished that such a method were
applicable to the reprinting of facsimiles of old and scarce
books. This, however, would require the sacrifice of two copies,
since a leaf must be destroyed for each page. Such a method of
reproducing a small impression of an old work, is peculiarly
applicable to mathematical tables, the setting up of which in
type is always expensive and liable to error, but how long ink
will continue to be transferable to stone, from paper on which it
has been printed, must be determined by experiment. The
destruction of the greasy or oily portion of the ink in the
character of old books, seems to present the greatest impediment;
if one constituent only of the ink were removed by time, it might
perhaps be hoped, that chemical means would ultimately be
discovered for restoring it: but if this be unsuccessful, an
attempt might be made to discover some substance having a strong
affinity for the carbon of the ink which remains on the paper,
and very little for the paper itself.(2*)

103. Lithographic prints have occasionally been executed in
colours. In such instances a separate stone seems to have been
required for each colour, and considerable care, or very good
mechanism, must have been employed to adjust the paper to each
stone. If any two kinds of ink should be discovered mutually
inadhesive, one stone might be employed for two inks; or if the
inking-roller for the second and subsequent colours had portions
cut away corresponding to those parts of the stone inked by the
previous ones, then several colours might be printed from the
same stone: but these principles do not appear to promise much,
except for coarse subjects.

104. Register printing. It is sometimes thought necessary to
print from a wooden block, or stereotype plate, the same pattern
reversed upon the opposite side of the paper. The effect of this,
which is technically called Register printing, is to make it
appear as if the ink had penetrated through the paper, and
rendered the pattern visible on the other side. If the subject
chosen contains many fine lines, it seems at first sight
extremely difficult to effect so exact a super position of the
two patterns, on opposite sides of the same piece of paper, that
it shall be impossible to detect the slightest deviation; yet the
process is extremely simple. The block which gives the impression
is always accurately brought down to the same place by means of a
hinge; this spot is covered by a piece of thin leather stretched
over it; the block is now inked, and being brought down to its
place, gives an impression of the pattern to the leather: it is
then turned back; and being inked a second time, the paper
intended to be printed is placed upon the leather, when the block
again descending, the upper surface of the paper is printed from
the block, and its undersurface takes up the impression from the
leather. It is evident that the perfection of this mode of
printing depends in a great measure on finding some soft
substance like leather, which will take as much ink as it ought
from the block, and which will give it up most completely to
paper. Impressions thus obtained are usually fainter on the lower
side; and in order in some measure to remedy this defect, rather
more ink is put on the block at the first than at the second
impression.





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