Chapter II: Preface

Mr. Sidney Morgan's work on Plantation Rubber in the East is so well known that he hardly needs introduction.

An earlier book, published in 1914, by the Rubber Growers' Association, entitled "The Preparation of Plantation Rubber," was well received and widely read. This book dealt in a very practical manner with problems with which the industry had to contend. A second edition was subsequently published. Both editions are now out of print. The present opportunity was therefore taken to revise the original work, with the result that it has been enlarged and practically rewritten. The information given is brought up-to-date, and covers the whole process of production, commencing with the planting of the tree, passing on to the collection, coagulation, and curing of the rubber, and concluding with the packing for export. In the course of his work for the Association, Mr. Morgan carried out a great deal of industrial research in rubber production, including lengthy experiments on tapping, the use of different coagulants and different conditions of coagulation, and also on varying modes of rolling, drying, and smoking rubber. He also went very fully into the types of construction and details of the machinery and buildings employed on estates.

Much of this valuable work has escaped notice, owing to its having been published in reports with limited circulation. Also a great deal of information was supplied to planters in a quiet and unobtrusive fashion, in interviews, visits to estates, and on other similar occasions. The knowledge and experience thus accumulated has been embodied in the present volume. The subject-matter should interest not only those actually engaged in rubber planting, but those otherwise directly or indirectly connected with the industry, such as importers, brokers, and particularly the rubber manufacturers in this country and in America. My experience has been that manufacturers as a whole have but a vague idea as to the methods employed in the preparation of plantation rubber, and this work provides them with the opportunity of obtaining an insight into the actual operations on the estates. It is most desirable that a closer bond should unite the plantation and manufacturing rubber industries. Such a result is best promoted by a better understanding of the problems with which each is confronted. Perhaps I may go so far as to suggest that some leading scientific officer in the employment of one of the large manufacturing concerns may take in hand a book which will give the planters the equivalent of information in regard to the manufacturing industry which the planters are now offering to the manufacturers.

The photographs in the earlier part of the book will give the layman some conception of the enormous amount of labour that must be expended in the opening up, planting, trenching, and weeding the plantations which have replaced the virgin jungle. The authors are indebted for most of these photographs to Mr. H. Sutcliffe, one of the mycologists of the Rubber Growers' Association. The pictures of spotless coagulating tanks and tiled verandahs regularly hosed down will indicate the cleanliness necessary for the preparation of the beautifully clean sheet and crepe rubber which became available with the advent of plantation rubber. These results are largely due to the work of Sidney Morgan and his colleagues, on whom the planters have relied for technical guidance and advice.

As regards my own contribution this is confined to a general outline of the subject. I have, therefore, omitted reference to a number of matters which would have been dealt with in detail had space permitted. The information given is based on researches on vulcanisation carried out for the Rubber Growers' Association by the writer over a period of nine or ten years. It was not found practicable to give detailed references in all cases. The reports on which the conclusions are based will, however, be found among the regular quarterly reports made by the writer for the Association up to June, 1919. Subsequent reports have been published in the Monthly Bulletin of the Rubber Growers' Association. We are indebted to the Association for permission to publish details from these reports, and also for the use made of numerous earlier reports published both in London and in the East.

CONTENTS

PART I
_FIELD OPERATIONS_

PAGE
CHAPTER I
PLANTING

Seeds--Seed selection--Strain improvement by bad propagation--
Nurseries--Stumps--Seed at stake--Basket plants--Preparation
of land--Danger of disease--Clean clearing--Loss of top-soil--
Silt-trenches on slopes 1

CHAPTER II
FIELD MAINTENANCE

Clean weeding--Selective weeding--Loss of top-soil--Grass
ridges--Lallang eradication--_Mimosa gigantea_ (_M.
invisa_)--Green cover-plants--Connection between weeding,
soil conservation, and soil improvement 13

CHAPTER III
THINNING OF AREAS

Original planting per acre--Ultimate stand per acre--Close-
planting _versus_ wide-planting--When to commence
thinning operations--How to select in preliminary rounds--
Later selections based on yields of individuals--Yields per
tree, present and future--Trees per acre 19

CHAPTER IV
TAPPING SYSTEMS

Former methods--Former systems--Tendency to reduce number of
tapping cuts and frequency of tapping--Period allowed for
bark-renewal--Modern systems--Superimposed cuts--Single cuts,
etc.--Tapping experiments--R.G.A. experiment--Alternate-daily
_versus_ daily tapping 28

CHAPTER V
TAPPING AND COLLECTING

Tapping knives--Personal equation in use of knives--Choice of
latex cups--Cleaning of cups--Water in cups--Premature
(spontaneous) coagulation--Prevention of spontaneous
coagulation--The use of anti-coagulants in the field--
Collecting pails--Payment by result--Methods for calculation
of yields per coolie--Tree-scrap, oxidation of--Prevention of
oxidation--Bark-shavings--Collection and storage of shavings--
Treatment of shavings--Collection of earth-scrap 38

CHAPTER VI
TRANSPORT OF LATEX AND COAGULUM

Percentages of "first" latex and other grades--Early
collection of latex--Transport, nature of--Light railways--
Motor-lorries--Bullock-carts--Care of transport vessels--Use
of an anti-coagulant during transport--Transport by coolie--
Coagulation centres (stations)--Transport of coagulum 59

PART II
_FACTORY OPERATIONS_

CHAPTER VII
PRELIMINARY TREATMENT OF LATEX

Reception at store--Receptacles--Jars--Tanks--Necessity for
close supervision--Need for utmost cleanliness--Straining of
latex--Strainers--Facilitation of straining--Bulking of latex
--Standardised dilution of latex--Facilities for receiving and
handling latex--Reception verandahs--Receiving vessels--Types
of installations 65

CHAPTER VIII
COAGULATION

Choice of coagulant--Strength of acid solution--Making stock
solution--Quantity for use--Quantities under modern
requirements--Care in mixing--Method of mixing with latex--Use
of sodium bisulphite as an anti-oxidant--Quantities for use--
Formulae--Abuse of the chemical--Residual traces in the dry
rubber--Use of sodium sulphite as an anti-coagulant,
quantities for use--Formulae--Use of Formalin as anti-coagulant
--Formulae for use 74

CHAPTER IX
PREPARATION OF SHEET RUBBER

Pale (air-dried) sheets--Uniformity of product--Pans _versus_
tanks--The ideal tank--Modern installations--Care of tanks--
Standardised dilution of latex--Variation in dimensions and
density of coagulum--Standardising instruments--Method of
using--Skimming latex--Style of sheets--Standard sheets--
Rolling and marking--When to work the coagulum--Hand-rolling--
Power smooth-rolling--Marking rolls--Preparation for smoke-
curing--Caution against accumulation of wet sheets--Hot-water
treatment--Dripping in the open air--When to place in smoke-
house 89

CHAPTER X
PREPARATION OF CREPE RUBBER

First consideration, fine pale crepe--Standardised dilution of
latex--Coagulation and coagulant--Quantities of coagulant--
Colour of rubber--Sodium bisulphite (use of)--Evaluation and
deterioration of the bisulphite and sulphite of sodium--To
distinguish between these two chemicals--Care of sodium
bisulphite--Mixing solution with latex--Former methods of
making pale rubber--Working the coagulum--Lower grades of
crepe--Naturally coagulated lump--Skimmings and washings--
Tree-scrap--Bark-shavings--Earth-scrap--Fibrous matter in low-
grade rubbers--Scrap-washers--Compound crepes--Increased care
with lower grades--Block rubber from crepe--Smoked crepe
_versus_ sheet clippings 110

CHAPTER XI
DRYING OF RUBBER

Air-drying of crepes--Artificial driers for crepes--Vacuum
drying--Hot-air driers--Michie-Golledge system--Rate of air-
drying--When drying takes place--Increase in weight of drying
crepe--Differences in weight--Aids to normal drying--Smoke-
curing of sheet rubber--Instruments for recording temperature
--Temperatures of smoke-house--Period of drying--Fuels for
smoking--Sun-drying of sheet rubber--Artificial driers for
sheet rubber 132

CHAPTER XII
SORTING, GRADING, AND PACKING

Reducing number of grades--Reduction carried too far--R.G.A.
recommendations--Care in sorting--Choice of packing cases--
Bags--Bales--Folding of crepe--Mechanical folders--Care in
assembling--Methods of packing--Weight of contents--Short
weights 150

PART III
_MACHINERY AND BUILDINGS_

CHAPTER XIII
MACHINES

Quality of metal in rolls--Nature of roll-bearings--Brass
liners--Liners of alloy or of cast-iron--Adequacy of machines
--Arrangement of battery--Speed of machines--Gear ratios--
Grooving of rolls--Heating of rolls--Sheeting machines--
Lubrication--Trays--Position of battery--Drainage of battery--
Access to back of machines--Engines--Power 159

CHAPTER XIV
FACTORIES

General construction--Plenty of light--Floors--Drainage of--
How many storeys--Verandahs--Tanks, situation of--Designs and
lay-out--Drains--Water supply 172

CHAPTER XV
OTHER BUILDINGS

Drying-houses for crepe rubber--How many storeys--Ventilation
--Windows--Effect of light--Effect of direct sun-rays--Hot-air
houses--Smoke-houses--Various types--Ordinary smoke-houses--
General ventilation--Windows--Racks of supports--Floors--
Furnaces in general--Pit-fires--Pot-fires--Iron stoves--
Horizontal drum-furnaces--Rate of combustion--Brick stoves--
Pataling type of--Consumption of fuel--Floor of furnace room--
Roof--Brick built houses--"Third Mile" type--Jackson cabinet--
Devon type--Detailed description of--Barker patent design 178

CHAPTER XVI
OTHER BUILDINGS (_continued_), AND SITUATION OF BUILDINGS

Sorting-room--Packing room--Store rooms--Storage of rubber--
Need for special accommodation--Floor of store room--Local
conditions--Temperature and humidity--Incidence of moulds--
Effect upon smoked sheets--Tool-sheds and stores--Situation of
buildings--Position with respect to points of the compass--
Choosing a factory site--Centralisation--Decentralisation 211

PART IV
_THE FINISHED RUBBER_

CHAPTER XVII
DEFECTS IN CREPE RUBBERS

General style of finish--Dirty edges--Iron-stains--Rust-stains
--Oil-marks--Trays--Dirt--Holes--Greenish and tacky streaks--
Not due to oil _per se_--Tackiness and copper--Cotton and
other fibre--Bark and grit--Sand--Oxidation streaks--Yellow
streaks--Bisulphite streaks--Spot disease--Cause of--Influence
of rate of drying--Percentage of moisture--Humidity of
atmosphere--Prevention of disease--Infection by contact--
Outbreak of dormant spores--Rules to be observed--Surface
moulds or mildew--Tackiness in general--Full discussion of--
Experimental reproduction--Lack of uniformity in colour--
Defects in block rubber 223

CHAPTER XVIII
DEFECTS IN SHEET RUBBER

Defective coagulation--Coloured surface blotches--General
darkening of surface--Soft coagulum--Spongy underface--Tearing
--"Pitting" of surface--Thick ends or edges--Mis-shapen sheets
--Thick patches--Torn sheets--"Dog-ears"--Creases--Greasiness
of surface before smoking--Surface blemishes--Uneven
appearance--Variation due to oxidation--Colour when dry--
Surface gloss--Dull surface--Moist glaze and greasiness--
Virgin spots--Surface moulds or mildew--Black streaks or spots
--White or grey streaks--Rust--Theories on formation of--
Prevention of--Two methods--Other views on causation--Bubbles
--Causes of formation--In the field--In the factory--Blisters
--"Spot" disease in sheet rubber--Support marks--Stickiness--
Surface pattern--Sheet clippings--Other infrequent defects--
Dirt--Ash--Bark--Splinters 249

PART V
_GENERAL_

CHAPTER XIX
CHOICE OF COAGULANT

Acetic acid in general use--Is a coagulant necessary?--Acetic
acid--Formic acid--Citric acid--Tartaric acid--Oxalic acid--
Sulphuric acid--Hydrochloric and nitric acids--Hydrofluoric
acid--Alum--Pyroligneous acid--Smoked water--Chinese vinegar--
Sulphurous acid--Sugars--Various salts--Proprietary compounds
--Carbonic acid gas--Alcohol--Vegetable extracts 278

CHAPTER XX
SPECIAL METHODS OF PREPARATION

Da Costa process--Byrne curing process--Freezing process--
Wickham process--Derry process--Spontaneous coagulation--
Definition of--Discussion of types--AErobic--Anaerobic--
Organisms--Maude-Crosse patent--Method of operation--
Accelerating action of sugars--Accelerating action of soluble
calcium salts--Ilcken-Down process--Slab rubber 290

PART VI
_VULCANISATION_

CHAPTER XXI
INTRODUCTORY DEALING WITH TREATMENT AND VULCANISATION

Wild rubber contrasted with plantation rubber--Milling and
mixing--Preparation for vulcanising--Vulcanising 301

CHAPTER XXII
TESTING OF PLANTATION RUBBER

Tests on raw rubber--Breaking strain--Behaviour of rubber
during milling, etc.--Preparation for testing--Tests on
vulcanised rubber--Choice of a formula--Physical tests 309