MAKING PAPER BY HAND

The very finest qualities of paper are usually made
without the addition of any _loading_, as it is called, but for
most other papers more or less loading material is added, according
to the quality of paper to be produced. The loading material used
for ordinary qualities is kaolin, or china clay, and for the better
qualities sulphate of lime or _pearl hardening_, as it is termed in
the trade. China clay, as it occurs in commerce, is in the form of
soft lumps and powder, is nearly white, and when rubbed between the
finger and thumb should present no hard particles of gritty matter.
To prepare it for mixing with the pulp it is first worked up into a
thin cream with water, which is usually done in a vessel furnished
with an agitating arrangement by which the clay becomes intimately
mixed with the water. The cream is then strained through a fine
sieve to separate any impurities present, and is then allowed to
flow into the beating-engine containing the stuff while in motion,
by which it soon becomes mingled with the pulp. The proportion of
china clay or other loading material which is to be introduced into
the pulp depends upon the quality of the fibre and the requirements
of the manufacturer, some makers using less of the material than
others. From 3 per cent. to 10 or 15 per cent. appears to be about
the extreme range for employing the material as a necessary
ingredient, in the production of various classes of paper, above
which figures the addition of loading material may be considered as
an adulteration. Sometimes nearly twice the largest amount named is
employed, no doubt to meet the exigences of keen competition–from
foreign sources especially.

One effect of the loading, whether it be china clay or sulphate
of lime, is to close the pores of the paper, whereby a smoother
surface is obtained, while at the same time, if the material has
been used in proportions suited to the quality of the fibre, and
not in immoderate excess, a stronger paper is produced. A species
of asbestos termed _agalite_ has been introduced as a loading
material, and since it has a fibrous texture, it blends with the
fibres of the pulp, forming, as it were, a vegeto-mineral paper. It
is stated that as much as 90 per cent. of the agalite used in the
beating-engine enters into the manufactured paper, while not much
more than half the china clay used is held by the pulp.

=Sizing.=–“Engine sizing,” as it is termed, consists in adding
certain ingredients to the pulp while in the beating-engine. The
materials generally used are alum and resin soap, in proportions
suitable to the paper to be produced. Resin soap is formed by
boiling ordinary resin in a jacketed pan such as is used by
soapmakers for preparing small quantities of fancy or other soaps,
with a solution of soda crystals in the following proportions:
Resin, 16 lbs.; soda crystals dissolved in water, 8 lbs.; and the
boiling is kept up for about two hours, or until a soap is produced
which is perfectly soluble in water. The method of preparing this
soap as conducted at the soapworks has been described in the
author’s work on soap-making,[22] p. 64, from which the following
abstract is taken: “Put into a pan capable of holding about 12
gallons, 2¼ gallons of fresh caustic soda ley at 30° B. Apply
gentle heat, and when the ley begins to boil throw in, every few
minutes, in small quantities at a time, finely powdered and sifted
resin until 37 lbs. have been introduced. The mixture must be well
stirred the whole time to prevent the resin from ‘clogging’ and
adhering to the pan. It is important to moderate the heat, as the
resin soap has a great tendency to expand and an excess of heat
would cause it to boil over. The heat, however, must be kept to
near the boiling point, otherwise the mass will become thick and
of a very dark colour. When kept at near the boiling point it is
always clear and its colour of a reddish yellow. If, during the
boiling, the resin soap rises and threatens to overflow, the heat
must be checked by throwing in a little cold water, only using
sufficient to effect this object. It is absolutely necessary to
stir the mass continually, otherwise the resin will agglomerate in
masses and thus prevent the alkali from acting freely upon it. The
boiling takes about two hours, when the soap is run into an iron
frame and allowed to cool. It is very important that the resin used
is freed from particles of wood, straw, etc., for which purpose it
should be passed through a tolerably fine sieve.”

Respecting the preparation of resin soap, Davis says:–“The
proportion of resin used to each pound of soda ash varies in
different mills, 3, 4, or even 5 lbs. of resin being used to each
pound of soda ash. The proportion of resin, soda ash, and water,
can be best determined by practical experience, as no prescription
could be devised which would be suitable to every case.” M.
d’Arcet, who modified the proportions recommended by M. Bracconot,
recommends for the preparation of resin soap–

Powdered resin 4·80 parts.
Soda crystals at 80° (French, alkalimeter) 2·22 ”
Water 100 ”

Theoretically speaking, only 2·45 parts of alum would be required
to precipitate the resin; but the waters, which are almost always
calcareous, neutralise part of the alum. Crystals of soda are
much more expensive than soda ash, but on account of their greater
purity they are sometimes preferred to the latter. At the present
day the resin soap is preferably made by dissolving ordinary
resin with a solution of carbonate of soda under boiling heat in
a steam-jacketed boiler, the class of paper to be made governing
the quantity of resin to be employed. The boiling usually requires
from two to eight hours, according to the relative proportions of
soda ash and resin used–the greater the proportion of soda used
the less time is required for boiling–the process being completed
when a sample of the soap formed is completely soluble in water….
About 3 lbs. of resin to 1 lb. of soda is the usual proportion. The
resin soap is cooled after boiling by running it into iron tanks,
where it is allowed to settle, the soap forming a dense syrup-like
mass, and the colouring matters and other admixtures of the resin
rising to the top are easily removed. It is important to run off
the mother liquor (ley) containing the excess of alkali, for when
the soap is used it consumes the alum to neutralise it.”

When the impurities and ley have been removed the soap is dissolved
in water, and if, from imperfect boiling, a portion of the resin
is found not to have been saponified, a small quantity of a strong
solution of soda crystals is added to the water used for dissolving
the soap.

Where starch is used for stiffening purposes, the soap is mixed
with a quantity of starch paste in the proportion of 1½ part of
starch to 1 part of resin soap. Some manufacturers, Mr. Davis
states, mix the starch paste with the kaolin in lieu of mixing
it with the resin soap. In either case the materials should be
thoroughly strained before being added to the pulp. From 3 to 4
lbs. of the mixture of resin soap and starch paste to each 100
lbs. of dry pulp are about the proportions in which the size is
generally used, but the quantity added to the pulp in the beater
depends upon whether the paper is to be soft-sized or hard-sized.

Sizing is chiefly applied to papers which are to be written upon
with ordinary inks, and also, with a few exceptions, to printing
papers, the object being to close the pores of the paper and render
it non-absorbent, by which the spreading or running of the ink is
effectually prevented. While the finest lines may be written upon a
well-sized paper (as ordinary writing paper, for example) without
spreading in the least degree, a similar stroke of the pen upon
blotting paper, tissue, or unsized printing paper would spread in
all directions, owing to the highly absorptive property of the
cellulose.

The sizing of the pulp is conducted as follows:–After the
loading material has been introduced and well mixed, the resin
soap, previously dissolved in water, a little carbonate of soda
being sometimes added, is mixed with a paste of starch prepared
by dissolving starch in boiling water, and the mixture of soap
and starch is then passed through a fine sieve to keep back
any particles or lumps that may be present. The proportion of
the materials used in sizing vary at the different mills, each
manufacturer having formulæ of his own; about 1 part of resin size
to 3 of starch paste, and, say, from 9 to 12 lbs. of the mixture,
may be used for 300 lbs. of pulp; and, if preferred, the respective
ingredients may be put into the engine separately, a method adopted
at some mills. Some manufacturers of the finest papers, instead of
dissolving the starch in hot water, make it into a thin paste with
cold water, in which condition it is introduced into the pulp, the
object being to impart to the paper a particular feeling to the
touch which is not obtainable by other means.

The mixture of resin size and starch paste, with or without the
addition of water, is added to the pulp in the beater, in which
the pulp is circulating, and the engine allowed to run until the
materials are well incorporated in the pulp. At this stage a
solution of alum (about 28 to 30 lbs. for 300 lbs. of pulp), or
of sulphate of alumina,[23] is introduced, which causes the resin
soap to become “separated,” the sulphuric acid of the alum uniting
with the alkali of the soap and setting the resin and alumina
free in the form of minute particles; the resin in the subsequent
drying on the calenders becomes fused, as it were, and thus cements
the fibres and alumina together, at the same time rendering them
non-absorbent and improved in whiteness by the precipitated
alumina. Sometimes ordinary soap is added to the resin soap, which
is said to impart a higher finish to the paper in the operation of
calendering.

The so-called “concentrated alum,” which contains a higher
percentage of sulphate of alumina than the crystallised alum,
is considered the most economical in use, being proportionately
cheaper, and the variety known as “pearl alum” is specially
recommended. “Aluminous cake” is another preparation which has
found favour in many mills, but since it sometimes contains a
large excess of free sulphuric acid it requires to be used with
caution, since this acid, although it will brighten the colour of
some aniline dyes, will discharge the colour from others, while
at the same time it may injuriously affect the brass-wire cloths
of the paper machine. The alum solution should be prepared in a
lead-lined tank, fitted with a steam pipe for heating the contents
when required.

The proportions of the materials used in sizing differ considerably
in different mills, but the following may be taken as an average
for common writing and printing papers:–

Per 100 parts of dried pulp 10 to 12 parts of resin.
” ” ” 20 ” 30 ” starch.
” ” ” 10 ” 12 ” alum.

To the sizing solution is generally added from 30 to 50 parts
of kaolin. When a colour is present on which alum would have a
prejudicial effect this is usually replaced by about one-third of
its weight of sulphate of zinc. Many mineral substances have from
time to time been added to paper stock, principally to increase its
weight, and in 1858 Sholl took out a patent for adding carbonate
of lime, a substance which, however, had long been fraudulently
used in order to increase the weight, but he found it to have
the property of fixing the ink in the pores of the paper, thus
rendering it immovable. The only useful addition is kaolin, or some
similar aluminous compound, as it attaches itself to the fibre,
and, while giving the required opacity and a good surface, takes
both printing and writing ink well, and has the advantage, from a
manufacturer’s point of view, of increasing the weight. It has been
proposed that small quantities of glycerine be added to the pulp,
in order to give the paper greater flexibility, and especially to
give copying-paper the quality of taking up colour readily.[24]

=French Method of Preparing Engine Size.=–Thirteen pails of water
are boiled in a copper-jacketed pan capable of holding about 150
gallons; 90 lbs. of soda crystals are then introduced and allowed
to dissolve, when 200 lbs. of finely-powdered resin are gradually
introduced, with constant stirring, and the boiling is sustained
for about two hours after the last portion of resin has been added.
A further addition of water is now made by putting in five pails
of cold water, and the water is then boiled for an hour and a half
longer. The resin soap is then transferred to stock-chests, in
which it is allowed to remain for ten days or longer, fresh batches
being prepared in rotation, to meet the requirements of the mill.

To determine whether an excess of resin soap or of alum has been
added to the pulp, red and blue litmus papers should be employed,
the former turning blue if an excess of resin soap be present, and
the latter red when alum or sulphate of alumina is in excess. For
uncoloured papers the aluminous material should be added until the
pulp becomes faintly acid, which will be indicated by the blue
litmus paper turning slightly red when immersed in the pulp.

Besides resin soap, various substances have been proposed as sizing
materials, including wax dissolved in a strong solution of caustic
soda and precipitated with alum, but the cost would be an objection
to the use of this material except for the highest classes of
paper. It is stated that 12 lbs. of gum tragacanth to each 500 lbs.
of resin has been used in preparing some kinds of engine-sized
papers, and is said to impart to them an appearance equal to that
of tub-sized papers.

=Zinc Soaps in Sizing.=–According to a paragraph in the
_Papermakers’ Monthly Journal_, a somewhat novel method of sizing
is employed in Germany, which consists in the precipitation in the
stock of zinc soaps. Cottonseed oil soap or Castille soap is worked
up in the engine with the stuff, and after it has become well
mixed with the pulp a solution of sulphate of zinc is added, which
results in the formation of a white and heavy zinc soap, which is
insoluble, and adheres well to the fibres. The weight and whiteness
of the zinc soap are the main points in favour of this method,
which is said to yield good results.

=Colouring.=–The pulp, after passing through the various processes
described, although apparently white, invariably presents a yellow
tinge when converted into paper. To obviate this it is usual to
“kill” the yellow tint by adding to the pulp small quantities of
blue and pink colouring matters. The blue colours generally used
are ultramarine, smalts, and various aniline blues, and the pinks
are usually prepared from cochineal, either in a liquid form or as
“lakes” (compounds of cochineal and alumina) or aniline dyes, the
former being preferable, as it is not injuriously affected by the
alum used in sizing. The ultramarine should be of good quality,
otherwise it will become decomposed, and its colouring property
destroyed by the action of the alum, but more especially so if
the alum contains an excess of free acid. Smalts blue, which is a
kind of coloured glass, is not affected by acids. In preparing the
colouring matters for mixing with the pulp they must first be mixed
with water, and the liquid should then be strained, to keep back
any solid particles that may be present in the material. Aniline
blues should be dissolved in hot water, or alcohol, and then
diluted. Samples of the pulp are examined from time to time until
the desired effect is produced, which the practised eye of the
beater-man can readily determine.

=Animal or Tub-sizing.=–Another process of sizing, termed
“animal-sizing,” “tub-sizing,” or “surface-sizing,” is also
adopted in the manufacture of certain classes of paper, and is
either accomplished by hand or on the machine. The former method
having been elsewhere described (p. 132) we will now describe the
operation of sizing on the machine, to which the term tub-sizing is
also applied. The size employed, which is prepared from what are
called “glue pieces,” or clippings of “limed” and unhaired skins of
animals, requires to be as colourless as possible, in order that
the colour of the paper may not be injuriously affected by it.

=Preparation of Animal Size.=–This operation is generally
conducted at the mill, the materials from which the size is
produced being the cuttings or parings of animal skins and hides,
or _pelts_, which have undergone the processes of “liming” and
unhairing preparatory to being tanned. The cuttings, or _pates_,
commonly called “glue pieces,” are first soaked in a mixture of
lime and water, placed in large tubs for several days, after which
they are put into a wooden cylinder, or drum, five or six feet
in diameter, and about ten feet in length, which revolves upon
a horizontal shaft, which, being hollow, admits the passage of
water to the interior of the drum. The drum is perforated, and
revolves in a large tank, while a continuous stream of water is
allowed to pass through it, and the dirty water escapes through
the perforations in the drum. When the cuttings are sufficiently
cleansed in this way, they are transferred to an iron copper,
furnished with a false bottom and steam-pipe, or a jacketed pan.
The cuttings are next covered with water; steam is then turned
on, and the liquid brought to a temperature below boiling point,
or say, about 180° to 190° F., it being very important that the
liquid should not actually boil. This operation is carefully kept
up for twelve to sixteen hours, according to the nature of the
cuttings, by which time all the material excepting any membranous
or fatty matters that may be present, will have become dissolved
and a solution of gelatine obtained. The liquor is then allowed
to settle for a short time to allow fatty matters to rise to the
surface and membranous substances to deposit, and the fatty matters
must afterwards be carefully removed by skimming. The liquor should
next be strained to separate any floating particles of a membranous
character. Sometimes the gelatine solution is clarified by adding
a small quantity of powdered lime, which is thoroughly mixed by
stirring, after which it is allowed to rest. When it is found that
the impurities and lime deposit too slowly, a little weak sulphuric
acid is added, which, forming an insoluble sulphate of lime, the
solid matters quickly subside, leaving the liquor quite clear.
The solution is next filtered through felt, and is afterwards
treated with a solution of alum, which at first causes the liquid
to thicken and become nearly solid, but it becomes fluid again,
however, on the addition of more alum solution. When this condition
is finally attained, the liquid is ready for use in the process of
sizing. The addition of the alum (which should not contain any free
acid) to the gelatine greatly improves its sizing property, besides
preserving it from decomposition. The treatment of the glue pieces
for the purpose of obtaining gelatine solutions is fully described
in the author’s work on “Leather Manufacture,” p. 401.[25]

=American Method of Sizing.=–Another method of preparing size,
and which is adopted in America, is the following:–In large paper
mills the size is generally prepared in a room devoted to the
purpose, and is commonly situated near the machine. The finest
grades of light hide and skin clippings are used for No. 1 letter
papers, but less costly stock is employed for the lower grades of
animal-sized papers. To preserve the glue pieces the tanners and
tawers macerate the clippings in milk of lime and afterwards dry
them. As the clippings require to be freed from the lime, the first
treatment they receive at the paper-mill is to put them in large
wooden tubs partly filled with water, in which they are allowed to
soak for several days. They are afterwards more perfectly cleansed
by means of a drum-washer, such as we have before described. Fresh
hide and skin clippings, that is, those which have not been limed
and dried at the tanneries, and which are occasionally purchased
by the paper manufacturers, require to be used as soon as possible
after they arrive at the mill as they readily decompose, and are
placed in tubs partly filled with water, in which 2 per cent. by
weight of caustic lime has been dissolved. The pieces, if from
calfskins, are allowed to remain in the lime bath for ten to
fifteen days, clippings of sheepskins fifteen to twenty days, and
trimmings from heavy hides, as ox, etc., twenty-five to thirty
days, the milk of lime being renewed once or twice a week, and
the material well stirred from time to time. The glue-stock, as
it is sometimes termed, is afterwards thoroughly washed in the
drum-washer, and when this operation is complete the material is
spread out in the yard to drain, and when sufficiently dried is
ready for boiling, or may be stored until required for use.

To prepare size from the material treated as described, it is
placed in a boiler of cast or wrought-iron or copper, furnished
with a perforated false bottom, and capable of holding from 100
to 400 lbs. of the raw material, according to the requirements of
the mill. Several such boilers may be placed close to each other.
At the bottom of the boiler is a stop-cock for drawing off the
gelatine solution when required. When the requisite charge of
glue-stock has been introduced into the boiler, water is poured
over it and steam turned on, which passes through a pipe fixed
beneath the false bottom, and care is taken that the temperature
of the contents of the boiler should not exceed 200° F., which
heat is kept up for ten to eighteen hours, according to the
nature of the materials treated. The gelatine solution is drawn
off from the boiler as it is formed, into wooden tubs, and at the
same time carefully strained to remove membranous matters and
suchlike impurities. Several boilings are made from the same batch
of glue-stock, and all the solutions are afterwards mixed together
in the receiving tubs, and a solution of alum is added in such
proportions as to be recognised by tasting the liquor. One object
in adding the alum being to prevent the gelatine from decomposing,
more of this substance should be added in warm than in cold weather.

When the solutions are cool they are ready for use, and the
gelatine is removed from the receiving tubs and dissolved in a
separate tub as required for use, the dissolving tub being provided
with a steam-pipe. The proportion of water–which should only be
lukewarm–used in dissolving the gelatine varies from a quarter to
half the bulk of the latter, the nature of the fibre and thickness
of the paper regulating the proportion of water to gelatine, the
strength of the size liquors being greater for thin papers and weak
fibres than for thick papers and strong fibres.

The operation of sizing is considered one of the most difficult
and uncertain with which the paper-maker has to deal, since the
material (gelatine) is greatly influenced by the conditions of the
atmosphere, both as regards its temperature and humidity, while
the temperature of the liquid size itself has also an important
influence on the success of the operation. The condition of
the paper, again, also affects the result, for if it be highly
porous it will probably be weak, and consequently there may be
considerable waste during the process of sizing from the necessary
handling it is subjected to; moreover, should the paper have
been blued with ultramarine, a strongly offensive odour is often
imparted to it; this, however, may be obviated by employing fresh
size and drying the paper as completely as possible. There are two
systems of animal-sizing employed at the mill, namely, hand-sizing
and machine-sizing, which is also called tub-sizing, the former
being applied to papers of the finest quality. Papers that have
been made by the machine, after being cut into sheets, are
hand-sized, as described in the next chapter.

=Machine-Sizing.=–The lower-priced papers, to be machine-sized,
are first partly dried over a few cylinders, after which the paper
passes through a tank containing liquid size, from whence it passes
between two rollers, which squeeze out the superfluous size; it is
then wound on to a reel on which it remains some time to enable the
size to thoroughly permeate the paper, after which it is wound on
to another reel, and from thence it passes over a series of wooden
drums or cylinders, each of which is furnished with a revolving
fan; by this means the paper becomes dried slowly, whereby a more
perfect sizing of the material is effected.

=Double-Sized Paper.=–This term is applied to paper which, after
being sized in the engine in the usual way, is afterwards “surface
sized,” as it is called, with animal size in the manner described.

Respecting the drying of paper after it has been tub-sized there
seems to be some difference of opinion as to whether it is best
to hang it in a loft to dry or to dry it over the cylinders of a
drying machine. Upon this point the New York _Paper Trade Journal_
makes the following remarks:–“When the paper is passed through
the size-tub, it is again wet; the fibres expand, and their hold
on each other is relaxed. Now it must make a difference to the
subsequent strength and quality of this paper whether it be hung
up in a loft to dry or run over a drying machine. If it is hung in
the loft no strain is put upon it and the fibres are at liberty
to shrink, or slowly contract, in all directions; whereas if it
is run over a drying machine, consisting of from 50 to 100 reels,
the longitudinal strain prevents the fibres from shrinking and
reassuming their normal position in that direction. Attempts have
been made to obviate this defect by regulating the speed of each
section of the machine in such a manner as to allow for the
shrinking, but this only remedies the evil by preventing the paper
from breaking as it travels over the machine. Everything else being
equal, it would seem that loft-dried paper must be superior to that
dried over the drying machine. Our home manufacturers endorse this
view, inasmuch as they continue to prefer the system of loft-drying
to the less expensive machine methods.”

=Mr. Wyatt’s Remarks on Sizing.=–Mr. James W. Wyatt, in a
paper on the “Art of Paper-making,”[26] makes the following
observations on engine-sizing and animal-sizing which will be
read with interest:–“Engine-sizing renders the paper fully as
non-absorbent as animal size. The latter penetrates the sheets only
slightly and forms a coating or skin on each surface, whereas the
engine size surrounds each fibre and impregnates the whole mass.
Surface-sizing, however, produces a stronger, firmer sheet, and is
smoother for the pen to travel over; the manufacturer also gets
the benefit in the price of the paper of the additional weight of
the size, amounting to 7 per cent. on the average. On the other
hand, as the animal size is mostly a skin on the surface, if the
coating be broken anywhere by the use of a knife in scratching,
the paper will only imperfectly resist ink in that place, a great
disadvantage for account and office-books and ledgers. Engine-sized
paper is much cheaper to produce than animal sized, and is
therefore used principally for the lower qualities of writings and
for almost all kinds of printings where firmness and smoothness is
not so much a desideratum. Most tub-sized papers have a certain
portion of engine size mixed with the pulp. This not only ensures
the thorough sizing of the sheet, but also is a measure of economy
in reducing the absorbing power of the paper for the animal
size. Papers for ledgers and office-work are best given an extra
proportion of engine size to ensure their ink-resisting properties,
and they are also sized by hand in animal size and loft dried.” The
following rough estimate of the comparative cost in materials and
wages of engine-sizing and animal-sizing paper may be of interest:

Engine-sizing, per 20,000 lbs.:–

£ s. d.
Materials 5 2 0
Wages 0 12 6
———- d.
Total £5 14 6 Cost per lb. = 0·068
==========

Animal-sizing, per 20,000 lbs.:–

£ s. d.
Materials 36 0 0
Wages 4 10 0
———–
Total £40 10 0
===========

Under the old system of making paper by hand, the rags were
reduced to a fine state of division by a process of _retting_, or
slow putrefaction. The rags were first washed in water, and then
piled in heaps, in which condition they were allowed to remain
until they became tender, that is, readily pulled asunder by the
fingers. During the decomposition the rags not unfrequently became
rotten in some portions of the heaps, thus involving considerable
loss of fibre. The rags were next placed in a strong chest, in
which iron-shod stamping rods were fitted, and these by their
continued action gradually reduced them to a pulp. The stampers
were eventually superseded by the beating-engine, the invention
of a Dutchman, which received and still retains the name of the
“Hollander.” Other machines, as the duster, washing and breaking
engines, and the beating engine, have entirely taken the place of
the older system, which required the work of forty pairs of stamps
for twenty-four hours to produce one hundredweight of paper.

=The Vat and Mould.=–The pulp being prepared, is conveyed from
the beaters to the working vat, where it is diluted with water.
The vat is a wooden or stone vessel about 5 feet square and 4
feet deep, being somewhat wider at the top than at the bottom. A
steam-pipe is supplied to the vat, so that the pulp and water may
be heated to a convenient temperature for working, and an agitator
is also furnished to keep the pulp and water uniformly mixed. The
mould in which the pulp is raised from the vat to form a sheet of
paper, consists of a wooden frame, neatly joined at the corners,
with wooden bars running across, about 1½ inch apart, and flush
with the top edge of the frame. Across these again, in the length
of the frame, wires are laid, about fifteen or twenty in an inch,
which are placed parallel to each other. A series of stronger
wires are laid along the cross-bars, to which the other wires are
fastened; these give to what is termed “laid” paper, the ribbed or
“water-marked” lines noticeable in hand-made paper. Upon the mould
is fitted a movable frame, called the _deckle_ or _deckel_, which
must fit very neatly or the edges of the paper will be rough. The
mould and deckle form together a kind of shallow tray of wire.
Sometimes the mould is divided by narrow ribs of wood, so that two
or four sheets of paper may be made in one operation. Connected
with the vat is a slanting board, called the _bridge_, with copper
fillets attached lengthwise upon it, so that the mould may slide
easily along the bridge.

=Making the Paper.=–When preparing for work, the vat-man stands
on one side of the vat, and has on his left hand a smaller board,
one end of which is fastened to the bridge, while the other rests
on the side of the vat. An assistant, called the _coucher_, is at
hand, whose duty it is to handle the frames or moulds containing
the pulp after they have passed through the hands of the vat-man or
maker. The latter now takes in his hand a mould, and lays it upon
the deckle; he then dips the mould, with its deckle in its proper
place, into the vat of agitated pulp, and lifts up as much of the
pulp as will form a sheet of paper. This, as will be readily seen,
requires the greatest dexterity, since the workman has nothing
but his sense of feeling to guide him. It is said, however, that
practice gives him such a nicety of feeling in this respect that
he can make sheet after sheet of the largest-sized drawing papers
with a difference in weight of not more than one or two grains in
any two of them. Great skill is also required to hold the mould in
a perfectly horizontal position, otherwise during the felting and
settling of the pulp the sheet of paper would be thicker on one
part than another. The mould being held lengthwise, that is, with
the long parallel wires running from right to left hand, he gives
the mould a gentle shake from his chest forward and back again,
which is called the _fore-right shake_; this shake takes place
across the wires, not in the direction of their length. He next
gives a shake from right to left, and back again, the respective
movements thus propelling the pulp in four directions. The vat-man
now pushes the mould along the small board on his left, and removes
the deckle, which he connects to another mould and proceeds to
form another sheet of paper, and so on. The coucher, taking the
first mould in hand, turns it upside down upon a piece of woollen
felt-cloth, then removing the mould, he takes another piece of
felt and lays it over the sheet and returns the mould by pushing
it along the bridge to the vat-man, when he receives in return a
second mould to be treated as before.

In the above way felts and paper are laid alternately until a
pile of six or eight quires is produced, which is afterwards
submitted to pressure in a very powerful press. When sufficiently
compressed, the machine is relaxed, and the felts are then drawn
out, on the opposite side, by an operative, called a _layer_, who
places the felts one by one upon a board, and the sheets of paper
upon another board. The coucher then uses the felts again for
further operations. Two men and a boy only are employed in this
part of the work. In the evening all the paper made during the
day is put into another press, and subjected to moderate pressure
to obliterate the felt marks and expel a further portion of the
water. On the following day the paper is all separated, which is
called _parting_, again pressed, and is then transferred to the
drying-loft. The drying is effected by suspending the sheets of
paper upon a series of ropes, attached to wooden supports; ropes
of cow-hair are used for the purpose, as this material does not
stain the paper.

=Sizing and Finishing.=–When the paper is dry, it is taken down
and laid carefully in heaps ready for sizing, which is the next
operation to which the paper is subjected. The preparation of the
size from animal skins, etc., is described in Chapter XI. When
preparing to size the paper, the workman takes several quires of
the paper, and carefully spreads the sheets out in the liquid size,
which is placed in a large tub, taking care that each sheet is
uniformly moistened before introducing the next. The superfluous
size is afterwards pressed out, and the paper then “parted” into
separate sheets, which are again subjected to pressure, and finally
transferred to the drying-room, where they are allowed to dry
slowly. When dry, the paper is conveyed to the finishing-house, to
be again pressed and looked over by women, who, being furnished
with small knives, pick out knots and other imperfections and
separate the perfect from the imperfect sheets. The paper is now
again pressed, and then handed to the finisher, to be counted into
reams and packed, the reams being afterwards pressed and finally
tied up and conveyed to the warehouse for sale. When the paper is
required to be hot-pressed, this is done by placing each sheet of
paper alternately between two smoothed sheets of pasteboard, and
between each group of fifty pasteboards is placed a hot plate of
iron, and the pile then submitted to heavy pressure, whereby the
surface of writing paper acquires a fine, smooth surface.

=The Fourdrinier Machine.=–It is just ninety years since Louis
Robert, a Frenchman, devised a machine for making a continuous
web of paper on an endless wire-cloth, to which rotary motion was
applied, thus producing a sheet of paper of indefinite length.
The idea was subsequently improved upon by Messrs. Fourdrinier,
who adopted and improved upon M. Robert’s machine, and with the
valuable aid of Mr. Bryan Donkin, a young and gifted machinist,
in the employ of Mr. Hall, engineer, of Dartford, constructed a
self-acting machine, or working model, in 1803, which, from its
effectiveness and general excellency of workmanship, created
at the time a profound sensation. This machine was erected at
Frogmore, Hertfordshire; and in 1804 a second machine was made
and put up at Two-Waters, Herts, which was completely successful,
and the manufacture of continuous paper became one of the most
useful and important inventions of the age. From that period the
“Fourdrinier,” with some important improvements introduced by Mr.
Donkin, gradually, but surely, became established as an absolutely
indispensable machine in every paper-mill all over the world.
Although the machine has been still further improved from time to
time, those of recent construction differ but little in principle
from the original machine. An illustration of the machine is shown
in Fig. 25, the detailed parts of which are expressed on the
engraving.

=Bertrams’ Large Paper Machine.=–The principal aim in the
construction of the paper-making machine has been to imitate, and
in some particulars to improve, the operations involved in the
art of making paper by hand, but apart from the greater width
and length of paper which can be produced by the machine, the
increased rapidity of its powers of production are so great that
one machine can turn out as much paper in three minutes as could
be accomplished by the older system in as many weeks. The drawing
represents the modern paper-machine as manufactured by Bertrams,
Limited, who supplied one of these machines to Mr. Edward Lloyd,
for the _Daily Chronicle_ Mill, at Sittingbourne, which runs a
wire 40 feet long by 126 inches wide, this being, we believe, the
largest and widest paper-machine in the world. It is provided with
20 cylinders, chilled calenders, double-drum reeling motion, with
slitting appliance for preparing webs to go direct to the printer’s
office without the assistance of a re-reeling machine, and is
driven by a pair of coupled condensing steam-engines. On our recent
visit to Mr. Lloyd’s mill we were much struck with the excellent
working of this splendid machine.

In the illustration, as will be seen, there are two sets of
drying cylinders, while small cylinders, or felt drying-rolls,
from 16 to 24 inches in diameter, are introduced to the felts of
the cylinders, before the smoothing-rolls, which discharge the
moisture with which the felts are impregnated from the damp paper,
whereby a considerable saving in felts is effected. Messrs. Bertram
state that the highest speed yet attained has been by their own
machinery, and is 270 feet of paper per minute.

[Illustration: Fig. 25.]

The progress of the pulp after it leaves the beating-engines for
conversion into paper may be described as follows:–The valve at
the bottom of the beating-engine is opened, when the pulp flows
through a pipe into the stuff-chests, which are generally situated
below the level of the engines. The beaters are then rinsed with
clean water to remove any pulp that may still cling to them, the
rinsing water passing also into the stuff-chests.

=Stuff-chests.=–These are large vessels of a cylindrical form, so
that the pulp may have no corners to lodge in, and are generally
made of wood, though sometimes they are made of cast-iron plates
bolted together. The chests are of various dimensions, according
to the requirements of the mill, being usually about 12 feet in
diameter and 6 feet deep, having a capacity for 1,000 to 1,200
lbs. of stuff. To keep the pulp well mixed in the stuff-chest,
of which two are usually employed for each machine, a vertical
shaft, carrying two horizontal arms, each extending nearly across
the interior of the chest, are provided, which are only allowed
to revolve at a moderate speed, that is, about two or three
revolutions per minute, otherwise the pulp would be liable to work
up into knots, and thus form a defective paper. Motion being given
to the shaft, the rotating arms keep the pulp and water uniformly
mixed, at the same time preventing the pulp from sinking to the
bottom of the stuff-chest.

The pulp is next transferred to a regulating box, or “supply box,”
by means of a pump called the _stuff-pump_. The regulating-box,
which has the effect of keeping a regular supply of pulp in the
machine, is provided with two overflow pipes, which carry back to
the stuff-chests any superfluous pulp that may have entered them,
by which the stuff in the regulating-box is kept at a uniform
level, while the machine is supplied with a regular and uniform
quantity of the diluted pulp. The stuff-pump conveys the pulp
through a valve in the bottom of the regulating-box in a greater
quantity than is actually required, the superfluity returning
to the stuff-chests by the overflow pipes; thus the supply-box,
being always kept full, furnishes a regular and uniform supply
of pulp to the sand-tables, or sand-traps as they are sometimes
called. _Sand-tables_ are large wooden troughs, varying in size at
different mills, but Mr. Dunbar gives the following proportions for
a first-class sand-trap; namely, 14 feet long by 8 feet wide, and 8
inches deep. The bottom of the trap is covered with felt, sometimes
old first-press felt being used, and is divided into several
compartments by thin bars of lead or iron, or strips of wood, which
keep the felt in position, and also retain any particles of sand
or other heavy solid matter that may be accidentally present in
the pulp. For the purpose of diluting the pulp for the machine,
there is, attached to the inlet of the sand-traps, a box with
two supply-taps, one for the delivery of pulp, and the other for
water; and these being turned on, the pulp and water flow over the
sand-traps, and the diluted pulp then falls into the strainers,
which, while allowing the fine pulp to pass freely, keep back all
lumps of twisted fibre, and particles of unboiled fibre, which
latter, if not removed, would appear as specks on the surface of
the finished paper.

=The Strainers= are formed of brass or bronze plates, in which are
cut a very large number of narrow slits, which gradually widen
downward, so as to prevent the pulp from lodging. Each plate has
about 510 slits, and several plates, connected together by bolts,
constitutes the complete strainer. When in use, the strainer
receives a jogging motion, which is communicated to it by means of
small ratchet wheels keyed on shafts passing beneath the machine;
this causes the fibres to pass more freely through the slits. There
are many different forms of strainers, which have been the subject
of numerous patents. It will be sufficient, however, to give one or
two examples of improved strainers which have been more recently
adopted by manufacturers.

[Illustration: Fig. 26.]

=Revolving Strainer and Knotter.=–The revolving strainer, which
was invented by the late senior partner in the firm of Messrs. G.
and W. Bertram (now Bertrams, Limited), has since been extensively
adopted, and the present firm have introduced a patent knotter
in conjunction with the apparatus, the complete arrangement of
which is shown in Fig. 26. The standard size for these revolving
strainers is 7 feet long by 18⅜ inches wide on each side of the
four surfaces. The vats are of cast iron, and the apparatus is
supplied with driving gear, bellows, regulating boxes and spouts,
as necessary. The firm also supply these strainers with White’s
patent discs, and Annandale and Watson’s arrangement. A A are two
revolving strainers, as applied to the paper-machine, showing
gearing for strainers and bellows. B is the patent knotter as used
for two strainers. C is the counter-shaft overhead. D D is the back
shaft of the machine, and E E the wire of the paper-machine.

[Illustration: Fig. 27.]

=Self-cleansing Strainer.=–The same firm also introduced this
form of strainer, an illustration of which is given in Fig. 27. The
action of the strainer is described as follows:–

The pulp flows on to the strainer at A, and passes away through
the pipes B B. At C is a valve for the discharge of waste pulp.
The strainer plates have an inclination of about 1 inch in the
direction of their length, and in those which are nearest to A,
where the pulp enters, the slits are wider, the knots being pushed
forward by the energy of the flow. The vacuum pumps, D D, are
worked from the shaft E. The tubes F F are for supplying water to
the plates, by which the coarser particles of the pulp are pushed
forward, and the slits are thus kept clean. The strainer will pass
from 18 to 20 tons of the finest paper per week.

[Illustration: Fig. 28.]

[Illustration: Fig. 29.]

=Roeckner’s Pulp Strainers.=–This invention consists in
constructing boxes, with one or both ends open, forming the
strainers, fixed, or to slide in or out, so as to be readily
cleaned. One or more fans are fitted in these boxes, and are put in
motion from the outside, so as to cause what is called “suction”
through the strainers. One or a number of such boxes are fixed
into a vat, the open ends discharging the pulp which has passed
through the strainers to the paper-machine, and can be so arranged
that all the fans are worked on one shaft. The vat may be divided
into compartments, so that the stuff flows from one to the other.
Instead of boxes, the strainers may be formed of tubes, in which
suitable slits or perforations have been provided. The tubes will
be perfectly closed at one end, and the strained pulp, after
passing through them, will be delivered to the paper-machine from
their open ends, which may fit into a ring, so that when cleaning
is required they may be easily lifted out or in. The suction is
provided inside these tubes by the fans, which are oscillated by
suitable gear from the outside of the vat. The strainers may,
instead of being stationary, be attached to the fans and oscillate
with them, in which case the open ends would have to be attached
to the vat by an indiarubber or cloth ring, or the strainers may
oscillate whilst the fans are stationary. Any number of these
strainers may be fixed into vats, disposed vertically or otherwise.
In the vat A, Fig. 28, which receives the pulp to be strained,
are several tubes, _p p p_, with one end open, having slits in
them similar to strainer plates. Inside of these are two, three,
or more plates, _f f f_, Fig. 29, running the full length of the
tube fixed to the shafts, _s s s_, and to the sides of the tubes,
which serve as fans, besides giving strength to the tubes. The
shafts _s s s_ are carried in bearings at each end, and have each
one end projecting through, upon which are keyed levers, _h h
h_, which, being connected to a rod _r_, worked by an eccentric,
_e_, at the end, gives an oscillating motion to the tubes and
fans. Any number of tubes may be in the vat, and may either work
separately or divided. With several tubes it is preferable to have
them arranged as shown in the drawing by division plate _d_, so
that the accumulated “knots,” &c., may flow finally into the end
compartment (which will form an auxiliary strainer), and may be
mixed with more water, so that the fine pulp still contained in
the stuff can flow away through the slits and the knots, &c., be
taken out when necessary. The tubes should be placed so far apart
that a workman can get his hand between. The closed ends work free
in the stuff, while the open ends run through indiarubber sheet or
other material, fitted so well to the tube that the fibre can only
get through the slits of the tube to flow on to the paper-machine
through the channel at side by the sluice _v_. The arrows indicate
the direction of the flow of pulp.

[Illustration: Fig. 30.]

Mr. Dunbar says, “the straining power necessary to pass and clean
pulp in an efficient manner for 25 tons of finished paper per week
is two revolving strainers, consisting of four rows of plates, or 7
feet by 18 inches of straining surface on each of the four sides,
the plates being cut No. 2½ Watson’s gauge.”

After passing through the strainers the pulp should be absolutely
free from knots or objectionable particles of any kind, and in a
proper condition for conversion into paper.

=The Machine Wire and its Accessories.=–On leaving the strainers
the pulp passes into a vat, in which is a horizontal agitator,
which causes the pulp and water to become well mixed, and ready to
flow on to the endless wire-cloth of the machine. The wire-cloth is
made of exceedingly fine wire, the meshes ranging from 60 threads
and upwards to the inch, there being sometimes as many as 1,900
holes per square inch, but the meshes usually employed run from
2,000 to 6,000 per square inch. The ends of the cloth are united by
being sewn with very fine wire. The width of the wire-cloth varies
considerably, the greatest width being, we believe, that supplied
for the large machine at Mr. Edward Lloyd’s mill at Sittingbourne,
which is 126 inches. The length of the wire-cloth is generally from
35 to 40 feet, the latter being considered preferable. Beneath the
wire is placed a shallow box called the “save-all,” which receives
the water as it flows through the wire cloth from the pulp. In
order to effect a further saving of pulp which escapes through the
meshes of the wire-cloth, a machine called a “pulp-saver” is used
at some mills, through which the backwater, as it leaves the box or
save-all referred to, is passed.

The wire-cloth is supported by a series of brass tube rolls, which
are so placed as to render the layer of pulp on the wire absolutely
uniform, by which a regular thickness of the finished paper is
ensured. The wire is attached to a malleable iron frame, having a
sole-plate of cast iron, and carries a brass or copper breast-roll,
18 inches in diameter, a guide-roll 7 inches in diameter, and four
brass or copper rolls 5 inches in diameter under the wire, with
shafts extending through the rolls, and furnished with brass bushes
and brackets, and a self-acting guide upon the 7-inch guide-roll.
The tube-rolls or “carrying tubes” are carried upon brass bearings.
Attached to the sole-plate of the wire framing are three cast-iron
stands on each side for supporting the save-all beneath the wire.
To regulate the width of the paper there is on the top of the wire
a set of brass “deckles,” carried on a brass frame passing over the
first suction box, of which there are two, and supported on the
wire frame by iron studs fixed in the frame. At each end of the
deckle-frame is a pulley for carrying the deckle-strap, with three
similar pulleys for expanding it. The deckle-frame is furnished
with two endless straps of india-rubber, these straps keeping the
pulp to the width required for forming ledges at the sides of the
web.

[Illustration: Fig. 31.]

=The Conical Pulp-saver=, which is shown in Fig. 31, was invented
by the late Mr. George Bertram and Mr. Paisley, and is manufactured
by Bertrams, Limited. Its use is to extract fibres from the washing
water before going into the river or otherwise. For the water
from the drum-washer, washing and beating engines, and for the
water from the paper-making machine, save-all, &c., it has proved
itself of great utility. It is simple in construction, small in
cost, takes up little room, and is easily repaired. When placed to
receive the washings from the beaters or paper-machine, the pulp
saved, if kept clean, can always be re-used. A is a conical drum
which is covered with wire-cloth, and it is made to revolve slowly
by suitable gearing. The water enters by the pipe B, which is
perforated, as shown, and passes through the meshes of the gauze,
while the pulp gradually finds its way to the wider end of the
drum, where it escapes into the box C, and can be conveyed again to
the beating-engines.

[Illustration: Fig. 32.]

[Illustration: Fig. 33.]

=The Dandy-roll.=–When it is required to produce a design or name,
termed a _water-mark_, upon the paper, this is done by means of a
roll called the _dandy-roll_, which consists of a skeleton roll
covered with wire-cloth, upon which the design is worked by means
of very fine wire. If the paper is required to be alike on both
sides, without any specific pattern or name upon it, the roll is
simply covered with wire-cloth, the impressions from which upon the
moist pulp correspond with those of the machine-wire on the under
surface. By this means paper known as “wove” paper is produced. A
dandy-roll of this character is shown in Fig. 32. “Laid” paper,
as it is termed, is distinguished by a dandy-roll having a series
of equidistant transverse wires on the upper surface of the wire
cylinder, as shown in Fig. 33, the effect of which is to produce
parallel lines on the paper, caused by the pulp being thinner where
the moist paper is impressed by the raised wires, which renders the
lines more transparent than the rest of the paper. The dandy-roll,
which is usually about 7 inches in diameter, corresponds in length
to the width of wire on which it rests, and is placed over the
wire-cloth between the suction-boxes. The journals of the roll
turn in slits in two vertical stands, one behind the machine frame
and the other in front of it. The roll, however, rests with its
whole weight on the wire, and revolves by the progressive motion
of the wire. The stands which support the roll prevent it from
being influenced by the lateral motion of the wire. By thus running
over the surface of the pulp when the wire is in motion, this roll
presses out a considerable quantity of water, at the same time
rendering the paper closer and finer in texture. Dandy-rolls of
various lengths, and bearing different designs or patterns, are
kept at the paper-mills, and great care is exercised to preserve
them from injury.

=Water-Marking.=–Dr. Ure describes the following processes
for producing a design for a line water-mark:–1. The design
is engraved on some yielding surface in the same way as on a
copper-plate, and afterwards, by immersing the plate in a solution
of copper sulphate, and producing an electrotype in the usual
way, by which all the interstices become so filled up as to give
a casting of pure copper. This casting, on being removed from the
sulphate bath, is ready for attaching to the wire gauze of the
dandy-roll. 2. The design is first engraved on a steel die, the
parts required to give the greatest effect being cut deepest; the
die, after being hardened, is forced by a steam hammer into some
yielding material, such as copper, and all of this metal which
remains above the plain surface of the steel is subsequently
removed by suitable means; the portion representing the design
being left untouched would then be attached to the wire-gauze
as before. Light and shade can be communicated to the mark by a
modification of the above process, for which purpose an electrotype
of the raised surface of a design is first taken, and afterwards
a second electrotype from this latter, which consequently will be
identical with the original surface. These two are then mounted
on lead or gutta-percha, and employed as dies to give impression
to fine copper-wire gauze, which is then employed as a mould. Thus
absolute uniformity, such as could not be attained by the old
system of stitching wires together, is now attained in bank-notes
by the adoption of the above method. It may be mentioned that when
the moulds were formed by stitching the fine wires together to
form a design, no less than 1,056 wires, with 67,584 twists, and
involving some hundreds of thousands of stitches, were required to
form a pair of £5 note moulds, and it was obviously impossible that
the designs should remain absolutely identical.

Sometimes water-marks are produced by depressing the surface of the
dandy-roll in the form of a design, which causes the paper to be
thicker where the design is than in the rest of the sheet of paper.
This modification was invented by Dr. De la Rue.

=De La Rue’s Improvements in Water-marks.=–By one method, patented
in 1869, dandy-rolls, having a surface of embossed wire-gauze,
are used; the indentations in the gauze are inwards, causing a
thickening of the paper where they are brought in contact with
it. These thickenings correspond in form to the configuration of
the design or water-mark. The inventor has also affixed wire to
the surface of such dandy-rolls so as to form projections, in
order to thin the paper where the projections come in contact with
it, by which means light lines are obtained in the water-mark,
strengthening the effect of the thickened opaque design.

[Illustration: Fig. 34.]

By another patent, dated May, 1884, No. 8348, the inventor forms
the surface of the dandy-roll of wire-gauze embossed in such a
manner that parts of the surface of the gauze, corresponding to
the configuration of the design of the water-mark, are raised,
and project out from the general surface, and other parts
corresponding to the line shading of the design are depressed
below the level of the general surface. The accompanying drawing,
Fig. 34, shows diagrammatically, and greatly enlarged, a section
of a portion of the surface of a dandy-roll made in accordance
with this invention. _a_ represents the section of a ridge or
projection raised on the surface of the gauze; _b_ represents the
section of a groove or depression in the wire-gauze, which, with
other similar grooves, serves to produce an opaque shading to the
design. _c_ is an auxiliary ridge or projection, serving to define
the shading line, and to intensify it by driving the pulp into
the groove or depression _b_. Further effects may be obtained by
attaching wires to the dandy-roll, either in the usual way, where
the surface is unembossed, or upon the raised parts _a_, which
give the configuration to the water-mark. In place of forming the
ridges or projections _a_, which produce the configuration of the
water-mark, by raising portions of the wire-gauze above the general
surface, they may be formed by sewing on suitably shaped slips
of wire-gauze, or of sheet metal perforated all over with fine
holes, on to the surface of the gauze which is embossed with the
grooves _b_, but it is much to be preferred that both the ridges
_a_ and the grooves _b_ should be produced by embossing the gauze.
Water-marks may also be produced by placing sheets of finished
paper in contact with plates of copper or zinc, bearing a design in
relief, and submitting them to heavy pressure.

[Illustration: Fig. 35.]

=Suction-Boxes.=–These boxes, which are fitted under the wire,
are made of wood, and are open at the top, the edges being lined
with vulcanite. The ends of the boxes are movable, so that they
may be adjusted to suit the width of the paper required; they are
also provided with air-cocks for regulating the vacuum, which is
obtained by means of two sets of vacuum pumps, having three 6-inch
barrels to each set: a vacuum pump of this form is shown in Fig.
35. As the wire travels over these boxes, the action of the pumps
draws the wire upon them with sufficient pressure to render them
air-tight; by this means a large portion of the water which the
pulp still retains at this point becomes extracted, thereby giving
to it such a degree of consistency that it can stand the pressure
of the couch-rolls without injury. The backwater extracted by the
suction-boxes, as also that collected in the save-all, is added to
a fresh supply of pulp before it flows on to the sand-tables.

=Couch-Rolls.=–At the extreme end of the wire-cloth from the
breast-roll, and inside the wire, is the under couch-roll, from
which the wire receives its motion. This roll, which is of brass,
is usually about 14 inches in diameter, is carried upon a cast-iron
framing with brass bearings, and is ground to a working joint with
the top roll, which is also of brass, and 20 inches in diameter.
Both these rolls are covered with a seamless coating of woollen
felt. The upper roll rests upon the lower one, and the wire-cloth,
and the web of paper upon it, pass between the rolls, receiving
gentle pressure, by which the paper becomes deprived of more water,
rendering it still more compact. It is at this stage that the web
of paper leaves the wire-cloth, and passes on to a continuously
revolving and endless web of woollen felt, termed the “wet felt,”
from the moist condition of the paper. This felt, which is carried
on wooden rollers, is about 20 feet long, and is manufactured with
considerable care.

=The Press-Rolls.=–The paper now passes on to the _first
press-rolls_, which deprive it of a still further quantity of
water, and put it in a condition to bear gentle handling without
injury. The upper roll is fitted with a contrivance termed the
“doctor,” which keeps the roll clean by removing fragments of paper
that may have become attached to it. The doctor is furnished with
a knife which passes along the entire length of the roll, pressing
against it from end to end. These rolls are generally of iron,
jacketed with brass, the under one being 14 inches in diameter, and
the top roll 16 inches. Sometimes this roll is made of fine-grained
cast-iron. When the roll is of iron the doctor blade is steel; but
when this roll is brass the knife is of the same material. The
under surface of the paper, which has been in contact with the
felt, and necessarily being in a moist condition, receives more or
less an impression from the felt over which it travelled, while the
upper surface, on the other hand, will have been rendered smooth
by the pressure of the top roll of the first press. To modify
this, and to render both surfaces of the paper as nearly uniform
as possible, the paper passes through another set of rolls, termed
the _second press-rolls_, in which the paper becomes reversed,
which is effected by causing it to enter at the back of the rolls,
which rotate in a reverse direction to those of the first press, by
which the under or wire side of the paper comes in contact with
the top roll of the press. By this arrangement the underside of
the paper is rendered equally smooth with the upper surface. The
second set of press-rolls is provided with an endless felt of its
own, which is usually both stronger and thicker than that used in
connection with the first press-rolls. In some mills each set of
press-rolls is provided with a doctor, to prevent the web of paper
from adhering to the metal. Sometimes the doctor knives are made
from vulcanite, a material which would seem specially suited for a
purpose of this kind. From this point the paper passes to the first
set of drying cylinders.

=The Drying Cylinders.=–The invention of the steam drying cylinder
is due to Mr. T. B. Crompton, who, in the year 1821, obtained a
patent for this useful addition to the paper-machine. Since that
period, however, the system of drying the paper by steam-heat has
been brought to a high state of perfection; not only this, but
the number of cylinders has gradually increased, while the heat
to which they are raised has proportionately decreased, and as
a consequence the size, which is injuriously affected by rapid
drying, is gradually deprived of its moisture, and thus renders
the paper closer and stronger, while at the same time a very rapid
speed can be maintained. The drying cylinders in the machine shown
in the engraving are 4 feet in diameter and 12 in number, being
arranged in two groups of 8 and 4 cylinders respectively, and in
the aggregate present a very large drying surface, it being very
important that the operation should be effected gradually, more
especially at its earlier stages. There is a passage between the
second press-roll and the cylinders, through which the machine-men
can pass from one side of the machine to the other. The first two
or three of the first section of cylinders are only moderately
heated, and having no felt on them, allow the moisture from the
paper to escape freely. The next five cylinders, however, are
provided with felts, which press the paper against the heated
surfaces, by which it becomes smooth and flattened, thus putting it
into a proper condition for passing between the _smoothing-rolls_.
The cylinders are heated by steam, and are generally of decreasing
diameter, to allow for the shrinking of the paper during the drying.

=Smoothing-Rolls.=–These consist of highly polished cast-iron
rolls, heated by steam. The paper being in a somewhat moist
condition when it passes through these rolls, they have the effect
of producing a fine smooth surface.

The paper next passes over the last four drying cylinders, all
being provided with felts, to keep the paper closely pressed
against their heating surfaces, by which the remaining moisture
becomes expelled and the paper rendered perfectly dry. The paper
now passes through the calender rolls, and is then wound on to
reels at the extreme end of the machinery. The operation of
calendering will be treated in the next chapter.

[Illustration: Fig. 36.]

=Single Cylinder Machine.=–For the manufacture of thin papers,
as also for papers which are required to be glazed on one side
only, a single cylinder machine, called the Yankee machine, has
been introduced, a representation of which is shown in Fig. 36.
It is constructed on the same principle as the larger Fourdrinier
machine up to the couching-rolls, when the paper leaves the
wire-cloth and passes on to an endless felt running round the top
couch-roll, and passes from thence to a large drying cylinder,
which is about 10 feet in diameter and heated by steam, the surface
of which is highly polished, giving to the surface of the paper
in contact with it a high gloss. There is attached to the machine
an arrangement for washing the felt for the purpose of cooling
and opening it out after passing through a cold press-roll and
the hot drying cylinder. This machine, as manufactured by Messrs.
Bentley and Jackson, for cap, skip, and thin papers, consists of
a rocking frame, and wrought-iron side bars, fitted with brass
bearings, the necessary brass and copper tube-rolls, couch-rolls,
with driving shaft, stands and pulley; self-acting wire guide,
brass deckle sides and pulleys, brass slice, vacuum boxes, pipes
and cocks; wet felt frame, with the necessary water pipes and
cocks, and carriages to carry the couch-rolls and felt-rolls; the
necessary wet felt-rolls and a felt washing apparatus; one bottom
press-roll carried by brass steps, and fitted with compound levers
and weight; one large cast-iron drying cylinder about 10 feet in
diameter, and fitted with a central shaft, steam admission and
water delivery nozzles, two water lifters and pipes, a manhole and
vacuum valve, a large spur driving wheel, spur pinion, driving
shaft and pulley; massive cast-iron framework, with pedestals to
carry the cylinder; traversing steel doctor and frames; copper
leading roll and carriages, a pair of reeling stands fitted with
brass steps, friction pulleys and plates, regulating screws, etc.;
a wooden platform and iron guard rail, all carried by strong
cast-iron framing; the necessary pulp and backwater pumps, shake,
knotter, stuff chests, service cistern, pipes and valves, shafting,
pedestals, change wheels, pulleys, &c. These machines can be
obtained of any desired width.

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