THE PREPARATION OF PLANTATION
RUBBER

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THE PREPARATION

OF

PLANTATION RUBBER

BY

SIDNEY MORGAN, A.R.C.S.

VISITING AGENT FOR ESTATES IN THE EAST; FORMERLY SENIOR SCIENTIFIC OFFICER
AND NOW HONORARY ADVISER TO THE RUBBER GROWERS’ ASSOCIATION
IN MALAYA

WITH A PREFACE AND A CHAPTER ON VULCANIZATION

BY

HENRY P. STEVENS, M.A. (Oxon.,) Ph.D., F.I.C.

CONSULTING CHEMIST TO THE RUBBER GROWERS’ ASSOCIATION IN LONDON

CONSTABLE & CO. LTD.
LONDON : BOMBAY : SYDNEY
1922

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PRINTED IN GREAT BRITAIN BY
BILLING AND SONS, LTD., GUILDFORD AND ESHER

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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.

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CONTENTS

PART I FIELD OPERATIONS   CHAPTER I PLANTING   PAGE 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  

href="@public@vhost@g@gutenberg@html@files@35510@[email protected]#Sec5_1" class="pginternal" tag="{http://www.w3.org/1999/xhtml}a">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— Formulæ—Abuse of the chemical—Residual traces in the dry rubber—Use of sodium sulphite as an anti-coagulant, quantities for use—Formulæ—Use of Formalin as anti-coagulant—Formulæ 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—

href="@public@vhost@g@gutenberg@html@files@35510@[email protected]#Sec9_16" class="pginternal" tag="{http://www.w3.org/1999/xhtml}a">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—

href="@public@vhost@g@gutenberg@html@files@35510@[email protected]#Sec13_13" class="pginternal" tag="{http://www.w3.org/1999/xhtml}a">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—

tag="{http://www.w3.org/1999/xhtml}a">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

href="@public@vhost@g@gutenberg@html@files@35510@[email protected]#Page_278" class="pginternal" tag="{http://www.w3.org/1999/xhtml}a">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—Ærobic—Anærobic—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   CHAPTER XXIII THE PROPERTIES OF RUBBER   Raw rubber—Physical tests—Vulcanised rubber—“Inner qualities” of raw rubber—Defects of crepe and sheet—Variation in physical properties—Rate of cure—Influence of various factors in raw rubber on rate of cure—Other types of plantation rubber—Fine para 313   Index 327

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