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Fifth Impression.

In Large 8vo. Cloth. With 4 Plates and Several

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A Treatise on the Nature of India Rubber, its Chemical and Physical Examina-
tion, and the Determination and Valuation of India Rubber Substitutes. .
Including the Outlines of a Theory on Vulcanisation.
By carl otto WEBER, Ph.D.

"Replete with scientific and also with technical interest. . . . The section on physical
properties is a complete Hsum6 of everything known on the svLh]ect."—India-rubher Journal.

Second Edition. In Lar^e 8vo. Cloth. With 800 pages and
154 Illustrations. 30s. net.


Their Preparation and Properties, and Manufacture therefrom of
Candles, Soaps, and other Products.

By C. R. alder WRIGHT, D.Sc, F.R S.,

Late Lecturer on Chemistry, St Mary's Hospital Medical School ; Examiner in " Soap"
to the City and Guilds of London Institute.

Thoroughly Revised, Enlarged, and in Part Rewritten.
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come."— Industries and Iron.

Second Edition. Thoroughly Revised. Illustrated. 16.s. net.



"Certainly a GOOD and useful book, constituting a practical guide for students by afford-
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A Guide to the Preparation, Examination, and Application of all the
Pig-ment Colours in Practical Use.


AUTHORISED English Translation by Dr C. MAYER, of Burgdorf.
" Tliis comprehensive guide . . . useful and interesting."— 0(7 and Colour Trades Journal.

In Cr

8vo. Cloth. With Numerous Illustrations. 7s. 6d. net.


A Practical Guide to the Construction and Costing of Cotton Fabrics,

with Studies in Design.

By henry B. HEYLIN, -

Of the Koyal Technical Institute, Salford.
" Mr Heylin's text-book is a very reliable one. It is difficult to mark out any special points
among so much excellent matter."— Dyer and Calico Printer.

London: CHARLES GRIFFIN" AND CO., LTD., Exeter St., Strand, W.C 2.












Timitb IHumeroue 5Uu6trat(on0»






[All Eights Eeserved.]

ry /'^


The manufacture of rubber goods has grown to be so large an
industry, and includes such a variety of detail, that it is surprising
no comprehensive treatise on the subject has hitherto appeared.
The late Dr C. 0. Weber had promised a companion book to his
standard work The .Chemistry of India Rubber, but this was
prevented by his lamented death. As soon as the German book,
Handbuch der Guinmiwarenfabrikation, by Drs Heil and Esch,
appeared, the publishers of Dr Weber's book at once realised the
utility of an English edition, and arranged to add it to their
Technological Series.

The learned authors in their Preface indicate that their object
was to provide a work treating in a connected way the various
branches of the actual manufacture of rubber, or at least of such
branches as are of general importance, so that specialists in rubber
and others interested might have a complete treatise.

The book deals with the principles which apply to the manu-
facture of all rubber goods, and any advances which may have
taken place since the publication of the original work have been
solely in matters of detail, and do not lessen its value.

The English Editor has followed as closely as possible^ the
original text and its arrangement, adapting it where necessary in
regard to the machinery more generally in use in this country.

The subject being dealt with from the standpoint of the
manipulation of raw rubber subsequent to its leaving the planta-
tions, it has not been deemed necessary to discuss the very open
question of plantation-grown rubber, although this is a matter of
great importance, as upwards of a thousand tons were produced in
the year 1907.

Tlianks are tendered to several friends for kind assistance,
especially to Messrs D. Bridge & Co. and F. Sliaw & Co. of
Manchester, for valuable drawings and other illustrations.


Lour.HTON, Essex.
Reprinted 1919.



Plan and Arrangement of a Rubber-Goods Factory
Boiler-house and Engine-room — Space-distribution generally.




The Raw Material

Brief Survey of Rubber-yielding plants, collection of the latex, and
preparation from it of the Crude Rubber of Commerce — The Physical
aud Chemical Properties of Rubber — The Oxidation of Crude Rubber —
Crude Rubber Storage— The Mechanical Purification of Crude Rubber —
The Further Working-up of the Dried Rubber — The Mixing and Weigh-
ing Room— The Mixing Mills— The Calendei-s.


The Vulcanisation of Rubber

Early Methods — The Vulcanising Shop — The Press Shop— Plant for
Sulphur-bath Vulcanisation — Consideration of the Vulcanisation of
Proofed Fabrics by the Cold and Hot Processes — Results of J. Minder's
Experiments on Cold Vulcanisation.




The Mixings 100-119

Preparation of Golden Sulphide — Manufacture of Substitutes — Treat-
men c of Besk for use in Rubber Mixings — Asphaltum and Pitch as
Ingredients of Mixings — Fats, Oils, ParaflBn and other Waxes in Rubber


The Manufacture of Soft-Rubber Articles. . , " .

The Manufacture of Hose : {a) Vacuum and Pressure Hose, with and
■without Insertion, for Conveying Purposes ; {h) High-pressure Hose
(hose with braided insertion of hemp cotton or brass-wire) ; (c) Maimfac-
ture of " Spiral " Hose ; {d) Canvas Hose with Rubber Lining— Moulded




Goods, and Hollow articles such as Balls and Toys — Seamless Tubing
andShaped Cord— .Preparation of Sheet for "Mechanicals" — Pre&s-cured
Goods — Rubber Belting — Rubber Rollers — Pneumatic Inner Tubes and
Tyres, Pedal and Brake Rubbers and Cab Tyres — Soft-rubber Surgical
Goods, etc. — Enamelling Bands and Rings — Rubber Stamps — Water-
proof Cloth— Imitation Leather Cloth — "Cut-sheet" Rubber Shoes —
Insulated Wires and Cables — Compositions of Asbestos and Rubber-
Eraser Rubber— Para Sheet and Elastic Thread.


Manufacture of Ebonite 201-224

Preparation of Ebonite Dust — The Ebonite Mixing — Manufacture of
Tinfoil — Ebonite Rods and Tubes — Insulation Tubes — Ebonite Accumu-
lator Cases — Moulded Ebonite Goods — Buffing and Polishing Ebonite —
Ebonite "Mechanicals" — Imitation Ebonite — Moulding and Pressing
Imitation Ebonite Goods.

Appendix I. — The Regeneration or Reclaiming of Rubber

Waste as carried out in Rubber Factories . . 225-229

Appendix II. — Specific Gravity 230-231

FiVDEx 232-237



In accordance with the general scheme of this work, the scientific
and theoretical portions have been purposely limited to what was
absolutely necessary and essential, for the little that is known with
scientific exactitude about rubber must still be looked upon as more
or less fragmentary. The book, therefore, begins with a description
of a convenient factory and plant, theoretical questions being gener-
ally dealt with in connection with the practical matters on which
they bear, an arrangement which is likely to facilitate refei-ence.


In whatever sphere of industry a new enterprise be initiated it
is essential, in these progressive times, that the fullest possible use
be made of every real advance that has taken place and of every
substantial improvement brought about within that sphere. The
rubber industry is pre-eminently of that class which demands the
greatest possible degree of perfection in mechanical equipment, if
the universal competition of to-day is to be successfully met, and
at the same time a first-class product is to be put on the market.
As everyone interested in the matter is aware, the success of any
given class of rubber goods is largely a matter of confidence on the
part of the buyer, and a new product can only make its way side
by side with others already known if it ofiers some advantages to
buyers. The only way, however, in which it becomes possible to
offer such advantages, without detriment to profits, is by so adjust-
ing plant and equipment as to reduce the wages bill to a minimum,
by the adoption of economical methods of manufacture, and by
avoiding waste. In the first place, the buildings should be so
arranged that the separate workshops, in which the different stages
in the process of manufacture are carried through, are continuous with


one another. Extensive subdivision is not desirable. The different
branches of manufacture cannot well be separated from one another
without interfering with the possibility of general supervision. A
further very important point is with reference to the dust which is
produced during certain operations, and which is scattered about
the shop. In all processes of " niaking-up " rubber goods it is most
important to exclude, as far as possible, every trace of dust, in order





2 Ebonite iJSt

2 Gri'^d'og mills


Centrifugal ctnei

Heating la->'-
4 Washing mil's


6 Mixing mills


4 Sets or calenders

40 /Metres


40 Metres

80 Metres

Fig. 1.

to produce a thoroughly sound and serviceable article. An air-
cushion, for example, is of no use whatever if it develop leaky
seams, owing to particles of dust settling on the solutioned edges
of the rubber sheet while the article is being made up. On this
account a building with an upper floor is to be recommended, so
that all those branches of manufacture which must be kept free
from dust can be put into separate isolated shops. There still exist
many works which are arranged in just such a primitive fashion


as would serve the purpose of a smithy. One of the principal
sources of trouble arises from the roughness of the walls, on which
the dust settles, only to be disturbed by the slightest draught,
settling again on fabrics and rubber.

The engines and boilers should occupy a central position, and
the vulcanising plant should be situated close to the boiler-house.
The mills, again, should be near the engine by which they are
driven, so that the main shaft with which they gear may
be driven direct. In selecting the machinery for the works,
one's chief care should be to procure only such machines as
will, by their use, lead to economy in labour. The advan-
tages of particular machines will be indicated when dealing

Section A-B.




fx]^l>^IXI > < ^l>< I SdX '

771 y>}??^??????;?}?;/;.



Fig. 2, a.

with the separate branches of manufacture, and sundry faults in
construction will also be referred to.

Fig. 1 shows the ground-plan of a factory, fig. 2, A and B,
sectional elevations, and with the help of these the reader will be
able to form a clear mental picture from the following description.
The logical method in explaining the ground-plan is to begin with
the steam-production, or with the motive power, and to follow this
up with descriptions of the shops in the order in which they are
concerned in the actual processes of manufacture. In accordance
with the manufacturing sequence, theoretical chapters on vulcani-
sation and mixings are inserted after that which deals with the
raw material.

Boiler-house and Engine-room, and Space-distribution generaUy.—
The buildings marked A and B in fig. 1 serve to house the boilers
and engines for the production of steam and power, and of electric
energy for lighting purposes. Each of these separate buildings is
7 metres high, and is covered with a span roof of girder-work.

Building A contains the Cornish boilers, of about 100 square








with a

heating-surface, and the superheater. Steam for the engines
is generated in two boilers working at
180 lbs. pressure, whilst the other boilers,
working at 150 lbs., provide the steam
required for vulcanisation. The use of
fire-tube boilers is certainly much more
rational in a rubber factory than that
of water- tube boilers,- because in the case
of the former the great consumption of
steam which takes place in the vulcan-
ising processes, through the continual
opening and closing of the vulcanising
apparatus, can be more readily compen-
sated than in the case of the latter, the
steam-space of the fire-tube boiler being
by far the greater. With water-tube
boilers, on the other hand, in spite of
their greater heating surface, the irregu-
lar steam-consumption results in much
water being carried over, a circumstance
which, in the first place, is opposed to
economical working, and, secondly, may
be detrimental to the goods undergoing
vulcanisation ; we shall make special
reference to this point again later on.
The boiler-house is so arranged that it
can be enlarged without difficulty, so
that additional boilers may be conveni-
ently introduced at any time. Great
value is to be attached to the super-
heater, so that dry steam can always be
used in the vulcanising heaters. Besides
the boilers there are also in this building
the feed-pumps, the water-softener, and
the oil-separator for condensed steam.

The engine-room B, fig. 1, like the
boiler-house, of w^hich it is in a sense a
continuation, is 7 metres high by 15
metres wide ; its length is 12 metres. The
triple- expansion engine housed in it
the main shaft of the machine-room C (rope drive), together
100-H.P. generator used for driving the machinery in other




rooms. A generator for lighting purposes, together with a batter}^
of accumulators, is also situated in the engine-room.

The storey ed building C adjoins the engine-room B and the
vulcanising shop D. In this building are contained the mills and
various other machines, which are arranged in sets. The mixing
mills and calenders are not enclosed in any way, but the spaces
containing the washing plant, the grinding and waste mills, are
separated by means of glazed partitions. Adjoining these is the
plant for the preparation of substitutes and surrogates, followed
by the sheet-cutting shop, and finally by the mixing-room and
store for the batches of mixed rubber.

In the room C, which is not subdivided, and which is the
machine-room proper, places are found for the following, in addition
to the mills and calenders: all lathes and drills as well as tube
machines and other heavy machinery for the " mechanical depart-
ment," with the exception of machines for making hose and tubino-
with insertion.

The hose shop and the "mechanicals" department are in the
building G, which rims along the ends of C, D, E and F. The hose
shop, 40 metres long, is constructed with a span roof 15 metres
wide, and adjoins a storey ed building. The hose shop should be
built on the ground-level with a span roof so that the hose-
mandrels can be manipulated in it without difficulty. The vulcan-
ising shop, which is subdivided into three compartments, is
situated, as already pointed out, next to the boiler-house, in order
to avoid having to carry the steam an unnecessary distance to the
heaters. Compartment D contains the vulcanising " pipes " (auto-
claves), while the presses are in compartment F. Between these
two rooms is room E, which is used as a moulding shop.

The rooms on the upper floor are used for making up sundry
articles, such as balls, surgical goods, ebonite goods, waterproof
goods, etc. They are in direct communication with the vulcanising
shop by means of the lift H.

The spreading-machines and also the ebonite-dust plant are
located in a separate building I. The office buildings adjoin the
factory buildings G.


Brief survey of Rubber-yielding plants, collection of the latex, and
preparation from it of the crude Rubber of Commerce. — Considering
the groat importance of repairing as far as possible the damage
done by the ruthless destruction of rubber trees in the process of
rubber-collection — a point which has for years been repeatedly
insisted on by the technical press — one might have supposed that
these plants vo^ld long ago have been most carefully studied in
every aspect, and have become really well known. Actually,
however, our knowledge of even the most important of the
rubber - yielding plants is, as E. de Wildeman^ has recently
pointed out, still extremely meagre, despite the efforts put forth by
zealous workers. The object aimed at in the following pages is to
present to the man technically interested in rubber, a condensed
general survey of the methods of collecting the various commercial
sorts of crude rubber, so far as our knowledge extends at the

The rubber of commerce comes partly from the northern parts
of South America and from Central America, partly from Africa
and Madagascar, partly also from India and the neighbouring
islands, as well as from Polynesia.

At the present time the most important kind of commercial
rubber, and, broadly speaking, the best, is Para,^ which takes its
name from the capital of the Brazilian province of Para. Para is
obtained essentially from the latex of plants of the genus Hevea, of
which numerous species are indigenous to South America. About
thirteen of these species have so far been identified. Hevea hrazi-
liensis (Muller, Arg.) is at present the chief source of the rubber ;

^ " Caoutchoutiers de I'Amazonie" {Le Caoutchouc et la Gutta-percha, 1905,
ii. 129).

2 Pronounced Park



this species is found, according to E. Ule's investigations, principally
in the southerly portions of the country watered by the Amazon
and its tributaries. According to more recent observations, how-
ever, other species than those of Hevea contribute to the supply
of latex from which Para is prepared, and the Hevea latex is occasion-
ally worked up in admixture with that from species of SapiuTn ;
for example, the Tapuru, Murupita, and Siringorana. According
to !Franz Clouth^ Micranda siphonoides also contributes to the
production of Para, but information from other sources is to the
effect that, in spite of the wide distribution of M. siphonoides, its
latex is little used, for the sap is bitter and cannot be worked up
with Hevea latices. Moreover, the natives do not trouble to work
up Micranda latex by itself. ^ It must certainly be admitted that
the mixing together of different latices is not altogether desirable
in the interests of the quality of commercial " Para." Commercial
Para is produced not only in the Brazilian portions of the country
watered by the Amazon, but also in Bolivia and in certain parts of
Peru. Bolivian Para in particular is recognised everywhere as
being of excellent quality. This may be largely due to the fact
that the district^ from which Bolivian Para is derived are so extra-
ordinarily rich in Hevea trees of more than a hundred years old, it
being generally accepted that the latex from such trees is superior
both in quantity and quality to that obtained from relatively young
trees. On the other hand, the conditions of transport are such tha£
Bolivian Para invariably comes on to the market in a well-matured

The- collection of Para rubber in the above-named districts of
South America is carried out as follows. A contractor leases a
stretch of forest of convenient size from the Government, and fits
out gangs of labourers with tools and provisions. To each group
of labourers a district is allotted, containing about 100 to 150 rubber
trees. Footpaths having been made through the forest to the
separate trees, the tapping operation begins. With the aid of a
machado, a short-handled hatchet of American manufacture which
has now been generally introduced, incisions are made in the bark
of the tree to such a depth that, although the laticiferous vessels
are laid open, the vitality of the tree is not affected by numerous
incisions. This operation commences at daybreak. Beneath each
incision is fixed a small collecting vessel to catch the latex which
trickles out. About three hours after tapping, the cuts become

^ Gummi, Guttapercha^ und Balata, Leipzig, 1899, p. 74.

2 E. de Wildeiuan, Le Caoutchouc et la Gutta-percha, 1905, ii. 171.



sealed up again, and the latex which has flowed out is transferred
to larger vessels, calabashes. The cuts are reopened in the evening,
and yield still further quantities of latex. After about a week
fresh incisions are made, and the collecting process just described is
gone through again. A district (estrada) of 150 trees yields on an
average about forty-five litres of latex at each tapping. Assuming
that the whole collecting season includes twenty tappings, one estrada
will yield on an average about 900 litres of latex, from which about
400 kilos, of crude Para containing a normal percentage of moisture

will be obtained. The latex is taken
in the calabashes to the storage place,
and is there worked up to rubber in
A ^ V ^^^^ following way: — The latex is poured

^BB^^ S' ^% ' ^^^^^ ^^^ dishes, from which it is scooped

^^5^^ R^ 't o^t and poured over a thick stick, sup-

^^' R\, ; ported at one end on a rough wooden

framework, the stick with the adherent
latex being then rotated by the hands
while it is held in the smoke from a fire.
The formation of a thin pellicle of rubber
round the stick is brought about partly
by the heat of the fire, and partly by the
action of the chemical compounds con-
tained in the smoke, and over this pellicle
more latex is poured, the smoking pro-
cess being repeated. By the repetition
of this operation a ball of rubber is
gradually built up, consisting of innu-
merable superimposed thin pellicles.

In some districts special virtues are
ascribed to the smoke of a fire fed with
nuts of the urucuri or tucuma palm. Containing as they do
some 12 to 15 per cent, of mbisture, the balls of rubber are of a
more or Jess j^ellowish-white colour inside, frequently streaked
with lines of a darker colour, representing bands of lower moisture-
content, and surrounded by a dark, relatively dry, outside layer.
Some of these balls of rubber come on to the market without any
further sorting; some are first cut open and sorted by experts
at the ports of Manaos and Para. On cutting the balls open
a number are usually discovered in which the smoking process
has not followed the normal course, and which contain patches of
spongy lacunae containing serum ; such balls are designated " Entre-



fine " and not '' Fine " Para. Both Fine and Entrefine Para have a
pleasant, smoky, ham-like smell. A further distinction is made
bet'.veen hard-cure and soft-cure Fine Para; this, however, is not
accompanied by any appreciable difference in price. As to when
a Para may be designated hard-cure and when soft-cure, that is a
point that still requires clearing up. Disputes between buyer and
seller on the point are not infrequent ; hitherto they have generally
ended in favour of the seller, but there is little doubt that if some

Fig. 4.

generally recognised system of classification could be agreed upon,
the outcome of such disputes would be different. Finally, only
about 70 per cent, of the latex collected from Hevea, etc., is converted
into smoked Para. The remaining 30 per cent, cannot be smoked,
either because rubber has already separated from it spontaneously
in the various receptacles, or because the latex has coagulated while
flowing from the tree-trunk. The rubber obtained in this way is

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Online LibraryAdolf HeilThe manufacture of rubber goods : a practical handbook for the use of manufacturers, chemists, and others → online text (page 1 of 21)