Make clean the bed of the press and the impression segment of the
cylinder. Adjust the bearers a trifle above ordinary type height. See
that the impression screws have an even bearing on the journals, and
that the cylinder fairly meets the bearers. Select a suitable tympan or
impression surface.
The tympan may be the India-rubber cloth which is furnished with the
press, a thick woollen lapping cloth or blanket, several sheets of thick
calendered printing paper, or one or more smooth and hard pasteboards.
Each of these materials has merits not to be found in any other. Upon the
proper selection of the tympan the presswork in great measure depends,
and the pressman should be thus guided in making choice.
_A pasteboard tympan_ is most suitable for wood-cuts, for perfectly
new type, and for the best kinds of presswork. It is not suitable for
miscellaneous work, nor for heavy forms, nor mixed old and new type. If
the overlaying is properly executed, a pasteboard tympan will enable the
pressman to show a sharper edge and a more delicate impression of the
type than can be possible with any other, and it will wear the type less
than any other. But it will require a very tedious and careful making
ready, or it will prove very destructive to type.
_A woollen blanket_ is best adapted for old stereotype plates, for very
old type which has been rounded on the edges, for posters with large wood
type, and for all common work which requires a clear but dull impression.
For such work a woollen blanket will enable the pressman to make ready a
form more quickly than with any other material; but it is injurious to
new type, and incapable of producing a fine and sharp impression.
_Thick paper_ is much used for book-work. It also answers well for script
circulars and leaded forms. It will not answer so well for mixed old and
new type, nor for table-work with unequal heights of brass rule, nor
for mixed large and small type. It will prove most serviceable for the
average of light and fine presswork.
_The India-rubber cloth_ combines many good qualities not found in other
tympans: it has something of the density of the pasteboard, the hardness
and evenness of paper, and the flexibility of the blanket, combined with
an elasticity peculiarly its own. It will compass a greater variety of
work than any other: posters, script circulars, news and book forms,
stereotype plates, and old or new type, can all be well printed with
an India-rubber blanket. When it is intended to make one tympan answer
for all kinds of work, the India-rubber blanket will be found decidedly
superior to all others; but when very extra presswork is wanted, the
tympan must be specially adapted to the form of type.
There are forms for which none of these tympans are specially suitable.
For such cases careful pressmen combine two or more together,—as Welsh
flannel over rubber, or thin rubber over pasteboard or under paper.
These, however, are exceptional cases, and are only thus combined
when very good presswork is wanted from imperfect materials. Careful
observation of the _quality_ of the impression given by each style of
tympan will teach a pressman how to combine to the best advantage. As it
requires experience and discrimination, an arbitrary rule cannot be given.
Whatever may be the material selected, the tympan must be stretched very
tightly over the cylinder. All labour in overlaying is but thrown away
if this is not carefully attended to. A rubber or woollen blanket can
be secured at one end of the cylinder by small hooks projecting inward,
while it may be laced tightly with saddler’s thread at the other end; or,
by sewing on that end of the blanket a piece of canvas, it may be wound
tightly around the reel, and kept secure by the pawl and ratchet.
But paper and pasteboard require a different process,-viz.: Take a piece
of Nonpareil cherry reglet of the full length of the cylinder. Trim down
the paper or pasteboard to the width of the bed between the bearers, but
leave it a little longer than the impression segment of the cylinder.
Then crease the pasteboard at a uniform distance of half an inch from
the narrower end, and lay this creased part on the flat edge of the
impression segment of the cylinder, under the grippers. Put the reglet
over this, and bring down the clamps hard on the reglet, so as to bind
all securely. When this is done, a thin web of muslin may be stretched
over the whole, in the same way in which a blanket is laid on, and rolled
up tightly, which will prevent any slipping of the board or of the
overlays pasted on it.
A large poster, or newspaper form, or any large form with old type, will
require a soft roller with much suction. Book-work, wood-cuts, or fine
job-work, will require a harder roller, with very smooth, elastic, and
clinging surface. Coloured inks are best printed with a still harder
roller and with much less suction. All rollers should be perfectly clean,
and free from cracks or holes. The suitableness of these rollers cannot
well be explained by words: such a knowledge will be best acquired by
observation and experience. It may, however, be necessary to state that
one roller will not answer for all styles of presswork: the quality of
the work, the size and wear of the type, and the speed of the press, must
control the pressman in his choice.
Posters, with large wood type, require a semi-fluid ink, but not
surcharged with oil. Ordinary news-work requires a better grade, more
tachy, and finely ground. Good book-work should have a stiffer-bodied
ink, soft, smooth, and with little oil. Job ink, which is made expressly
for presswork on dry paper, should be used only for such work. Book and
job inks are not convertible: an ink for wet paper will not work well on
dry paper, and _vice versâ_. Very fine presswork—such as wood-cuts, or
letter-press upon enamelled paper—calls for an ink impalpably fine, very
stiff, of brilliant colour, and nearly or absolutely free from oil.
Every job-office should keep four grades of ink,—news, book, job, and
wood-cut. They can be compounded (if no ink-manufacturer is near) with
each other, or reduced with varnish to suit any form. Good presswork is
impossible without good inks.
Charge the ink-fountain with the ink selected, and keep it well covered,
to protect it from paper dust. Turn down the screws, and cut off all
the ink evenly. When the form is ready, turn on the ink cautiously, and
wait for ten or twelve impressions before again altering the screws. For
small forms and short numbers of any piece of presswork in coloured ink
or extra ink, a fountain is not necessary. The ink may be applied with a
brayer or palette-knife.
The adjustment of the margin is the next process. Although type can be
printed from any quarter of the bed, it will be found most judicious to
lay all forms close to the back part of the bed, and equidistant between
the bearers. This will secure a good impression, give a fair average
margin to every form, and allow the full use of the bed for a large form,
without resetting the cylinder. The bed and cylinder travel together, and
the grippers, which bring down the sheet to the form, should barely lap
over the back part of the bed. So long as the toothed cylinder wheel, and
the short toothed rack on the side of the bed, remain undisturbed, the
grippers will always pass over the bed in exactly the same place. When
the grippers are in this position, (slightly lapping over the back of the
bed,) take measurement of the distance between the back edge of the bed
and the point of one of the nearest grippers. With a piece of reglet cut
a gauge exactly corresponding to this measurement. Let no form be laid
upon the press until the distance between the type and the edge of the
chase tallies with the gauge. This will prevent the grippers from closing
on the form and crushing the type. If the chase will not admit of so wide
a margin, or if an extra margin is wanted on the sheet, put a piece of
furniture of the extra width behind the chase: the margin can thus be
increased or diminished at pleasure.
A book form may be locked up in a chase so large, with the type so far
from the edge of the chase, that the grippers will bring down the sheet
in such a position that it will be printed with the margin all on one
side. To remedy this, the cylinder must be reset. Proceed thus. Remove
the screw and washer, and draw the intermediate wheel out of gear, loosen
screws in the gauge rack, then turn the cylinder to the point required,
connect the intermediate wheel, adjust the gauge rack, and screw up tight.
The press having been adjusted, next examine the form to be printed.
Not only see that it is gauged correctly, but also see that it is not
locked up too tightly,—that chase, quoins, letter, and furniture are all
level, and lie flat upon the bed. If the form springs, the quoins must be
slackened; if this loosens the type too much, the justification should
be amended. Make clean the type by rubbing it over with a dry brush. The
rollers are often made foul and the colour of the ink changed by dust and
particles of dirt clinging to the type.
Fasten the form so securely on the bed that it will not be moved by the
action of the cylinder or the rollers. Take a proof on its own paper,
using very little ink. Proceed to adjust the drop guides so as to bring
the sheet exactly in the right position. Push out the iron tongues at the
edge of the feed-board, and at equal distances from each other, so that
they will equally sustain the paper. Slide the drop guides along the rod
until they fall squarely over the tongues. Set the side guide so that
it will give a true margin in length to the sheet to be printed. Adjust
the grippers so that they will seize the sheet at proper intervals,
making the margin exactly even by lengthening or shortening the drop
guides. Then take a clean proof _on its own paper_, exactly in the right
position, before making ready, when it may be shown to the reader. It
frequently happens that an error in the margin, or an imperfection in the
register, is thus noticed; and its timely discovery and correction before
overlaying will save much time and trouble. A readable proof may be taken
before overlaying, by running through a sheet or two of proof paper.
_Make register_, if it is a book form, _before underlaying_.
When every thing has been found correct, then proceed to regulate the
impression. If the type is fair, the proof should show a decently uniform
impression; but if the form is large, or if it contains old and new or
large and small type, then the proof will show an uneven impression. To
rectify this inequality, pressmen use many expedients.
1. By lowering the bearers and putting on more impression. This, of
itself, is a very poor way; for it wears down new type in order to show
the face of the old, and invariably produces thick and coarse presswork.
2. By raising the low type to a proper height with thicknesses of paper
under them, which is called _underlaying_.
3. By giving additional thickness to the tympan over every part of the
form which shows a weak impression, which is called _overlaying_.
It is very rare that any one of these modes will prove sufficient: all
should be used in conjunction. When the larger part of the proof-sheet
shows a weak impression, almost approaching illegibility, then more
impression should be added. When one side of the proof-sheet shows a weak
impression, while that on the other side is full and clear, then more
impression should be given to the paler side. The impression should be
made decently uniform before any attempt at overlaying or underlaying.
But the bearers should follow the impression screws, both being raised
and lowered together, in order to secure the type from the unimpeded
force of the impression cylinder. Not only should the bearers be of
even height, but the cylinder shaft should always revolve on a true
level. If the impression screws are carelessly used, and the bearers
are rashly raised and lowered, this even bearing will soon be lost;
the difficulty of obtaining a good impression will be much increased,
and the press will receive a serious injury. For the same reason, the
bearers should never be packed, (by the addition of cards, as is usual
on a hand-press,) for it strains the cylinder and all its bearings with
an irregular resistance. The bearers should be tampered with even less
than the impression screws. When the impression screws are so set that
the cylinder gives a fair uniform impression, they have done all that
can be expected, and nothing more should be attempted by them. Sometimes
the proof may show that a cut, or a line of type, or a set of brass
rules, are higher than any other material in the form. But the impression
should be set regardless of this: it will be found quicker and neater to
reduce the impression on one or two such high lines, by cutting _out_
the tympan-sheet over them, than it would be to underlay and bring up
all other types to such an irregular height. Pitch the impression so
that it will face the larger portion of the type, and make the less
conform to the greater. Those parts which are high must be cut out of the
tympan, and those which are low should be raised by underlays, and all
inequalities regulated by overlays.
When any part of the form is very low, it will not answer to attempt
facing it with overlays: it must be brought up to meet the inking rollers
as well as the impression cylinder. When the proof shows low type, cut
out the impression of it, raise the form, and paste it over the feet
of the letter. If some types are high and some are low, make proper
distinction, and carefully avoid increasing the height of any type or
rule which seems to have a full impression. Pursue the same course when a
marked depression appears in the centre, or a dwindling impression at the
edges. Cut out that section which is light, and affix it to the defective
part. If the impression dwindles in any part, the underlays must be cut
of irregular thickness to suit the tapering off of the impression. Cut
out an underlay from the edge where the impression begins to fade; then
cut another of smaller size where it is utterly illegible; paste one over
the other, laying them carefully in their proper positions, and then
paste them all on the bottom of the form, where it is needed, taking care
to lay the smallest underlay nearest the bed. This will restore the type
to a proper level, and the next proof should show a uniform impression.
The same plan will answer for a low corner. Use as little paste as
possible, thin and free from lumps. Be careful that the underlays are
laid on smoothly, without fold or wrinkle. Cut all underlays from a
proof; for the proof serves as a guide both in cutting and in affixing to
the form.
Underlaying should not be done to any great extent upon a cylinder press.
It is a valuable means of bringing up an old line of type, a hollow, or a
low corner. The underlays of any _type_ form should not constitute more
than one-fourth of the surface; if more than this is attempted, they will
rarely ever fail to work up the quadrates and furniture. The action of
the quickly moving cylinder upon a form of type underlaid with yielding
paper, must create a spring and a rocking of all the materials in the
chase.
Of all materials, old stereotype plates need underlays most, as they are
usually very irregular in height. Thin card or pasteboard will be found
preferable to paper for the underlaying of plates secured on wood bodies.
When the plates are on patent blocks, always underlay between the plate
and the block. Always cut the underlay for a plate less in size than the
faint impression would seem to require. This will allow for the spring of
the plate. If it is cut of full size, the next impression will disappoint
the pressman, by being much harder at the edges than he intended. Never
attempt to build up a type form to a proper impression entirely or
chiefly by underlaying.
Underlays should be put under all large and bold-faced types when used
with much smaller types, so as to raise them above the level of the
others. This is needed to give it closer rolling, extra supply of ink,
and that extra force of impression to transfer the ink to paper which all
large types require.
When the type has been so levelled by underlays that all parts receive
proper bearing from the inking rollers, and when the cylinder has
a corresponding even impression, then overlaying may be commenced.
For ordinary news, posters, or job-work, overlaying may be entirely
unnecessary; the tapes and fly may be set, and the printing of the form
may proceed without further delay. But fine press-work cannot be done
without overlays. Underlays are chiefly valuable for securing an even
impression; while overlays are indispensable for giving delicacy and
finish to that impression.
To overlay a form properly, the tympan should be covered with a sheet
of thin, smooth, and hard paper, stretched tightly. Then take a pale
impression on the tympan-sheet, and also run through the press two or
three proofs on thin and hard paper. Examine the proofs carefully on
both face and back. If any brass rules or letters appear too high, cut
them out of the tympan-sheet in one or two thicknesses, as their varying
height may require. Go over the whole proof, examining every line
carefully, and, by cutting out, reduce the impression of all projecting
letters to a uniform standard. For this, as for all other work on
overlays, use a very sharp knife with a thin point, and cut on a smooth
surface, so that there will be no dragged or torn edge to the cut.
The next step should be to raise the impression of those parts of the
form when the type appears dull or weak. Cut out carefully, and paste
the overlays over the tympan smoothly. Overlays are worse than useless
if they are not laid on firmly and smoothly, as the slightest bagginess
will cause slur or mackle. If, by accident, the tympan-sheets or overlays
should bag or wrinkle, tear them off, and commence anew.
Cut out and overlay the more prominent parts first; then try another
impression, and from that cut new overlays for minor defects. Thus
proceed until a perfectly smooth and even impression is obtained.
With common work it will be sufficient to cut overlays in masses, as
pages or parts of pages; but with fine work every line and letter needs
examination, and letters and parts of single letters are often overlaid
by careful pressmen. When the pressman is expert at making ready, it is
not necessary that he should take a new impression with every successive
set of overlays. Many pressmen take a dozen proofs of a form on different
styles of paper, and proceed to cut out and overlay on one of the proofs,
and finally paste this proof on the tympan. But this boldness and
precision can be acquired only by long practice. It is better for the
young pressman to feel his way step by step.
_The Impression._—A diversity of opinion exists among good printers
as to the proper force of the impression: by some a heavy and solid
indentation of the paper is considered necessary; while others insist
that an impression which does not indent the paper is preferable. But the
indentation of the paper is no test of the force of the impression. A
light impression against a woollen blanket will show more forcibly than a
strong impression against a paper or a pasteboard tympan.
Type is worn out not so much by the _direct_ impression of the platen
or cylinder on the flat face of a form, as by a grinding or rounding
impression on the edges of the type, caused by the forcing of the tympan
between the lines and around the corners of every letter. Every fount of
worn-out type, whether from cylinder or platen press, has suffered less
from a reduction in height than from a rounding of the edges. When the
type is new and the tympan hard and smooth, the impression can be made
so flat that the type will not round at the edges, and the impression
will not show on the paper. But this cannot be done with old type or with
a soft tympan: the impression must be regulated to suit the tympan.
On fine work, a rounding impression should be avoided, as it not only
destroys type, but also thickens the hair-line and wears off the ceriphs.
It is not sufficient that the paper should barely meet the type: there
must be sufficient force in the impression to transfer the ink from type
to paper. If there is not sufficient impression, it will be necessary
to carry much ink on the rollers; and this produces two evils: the
type is clogged with ink, and the form becomes foul; too much ink is
transferred to the paper, which smears and sets off for want of force
sufficient to impress it in the paper. Distinction must be made between
a _light_ and _weak_ impression and a _firm_ and _even_ impression. The
latter should be secured even if the paper is indented; though that is
not always necessary. But a form of old type, a poster, or other solid
form, must have a _heavy_ impression, or else a very tedious and careful
making-ready.
_To set New Tapes._—Pass the tape around and close to the cylinder. Lap
it over one of the tape pulleys, and then pass it around the small guide
pulley on the shaft above. To increase its tightness, throw up the guide
pulley from the shaft, and set the binding screw more tightly. All these
pulleys are movable on their shafts, and distance between them may be
altered at pleasure. Let the tapes rest upon the outer margin of the
sheet, and see that the overlays on the tympan over which the tapes pass
are of equal thickness; if not of equal thickness, the sheet will wrinkle.
_To set the Fly._—Run through a sheet of the paper to be printed, and let
it run down the fly so far that it is barely held by the fly pulleys.
Then set the cam which works the fly, so that its point just clears the
small friction roller on the shaft, and it will throw down the sheet
correctly. Tighten the spring according to the size of the sheet, and set
the spring crank so that it will prevent the fly from striking too hard
on the table.
It will be seen that good presswork does not depend _entirely_ upon the
press, nor yet upon the workman or the materials. Nor will a superiority
in any one point compensate for a deficiency in another: the newest
type will suffer from a poor roller, and the most careful making-ready
will be of no avail if poor ink is used. It is necessary that _all_ the
materials should be of the best kind,—that they should be well adapted
to each other, and fitly used. Although a good workman can do much with
insufficient materials, there are cases where a neglect to comply with
one condition is equal to a neglect of all.[19]