September 1, 1921 



THE INDIA RUBBER WORLD 



931 



The International Rubber Exhibition 



By George M. Naylor' 



PKACTRAi.i.v every naliuii in the world in tlic tropics, or pos- 

 sessing colonies in the tropics, was represented at the Lon- 

 don rubber exhibition this year, the principal government 

 exhibitors being : British Malaya, Ceylon, North Borneo various 

 British African colonies, and ligypt ; the Philippines. Nether- 

 lands East Indies, 

 I'Vench West Afri- 

 ca, French East 

 Africa, and Siam : 

 1^. e 1 g i a n -Congo, 

 Portugal, Madagas- 

 car, and Brazil. 



Other firm ex- 

 hibits represented 

 I states agents, rub- 

 ber manufacturers, 

 makers of rubber 

 m a c h i n e r y, re- 

 claimers of rubber, 

 dealers in chemicals 

 and rubber substi- 

 tutes, and dealers in 

 \arious tropical 

 products. A new 

 process for prepar- 

 ing crude rubber 

 was also shown. 



Probably the most 

 interesting of the 

 government exhibits 

 from the crude rub- 

 ber standpoint was 

 that of the Nether- 

 lands East Indies. There were pamphlets showing the research 

 work done at the Central Rubber Station. Buitenzorg, 

 Java, and translations of one or two lectures by Dr. 

 de Vries. A series of photographs showed the Central Rubber 

 Station. A display consisting of a piece of ribbed smoked sheet, 

 a piece of the sheet after breaking down, a third piece after com- 

 pounding, and finally some vulcanized test rings, conveyed the 

 idea that, as far as the final product is concerned, all efifort ex- 

 pended in making a nice-looking sheet is wasted. .Although it 

 may seem absurd to the rubber manufacturer, this is actually 

 news to some estate managers and to many rubber brokers in 

 Singapore. 



The method of testing samples ol rubber and several graphs 

 used for plotting the results of the tests were exhibited. The 

 progress made by estates in the Netherlands Indies in producing 

 a uniform rubber both in sheet and crepe was illustrated bv 

 several charts showing the varialiility in curing rate before, and 

 the uniformity in curing rate after adopting the standard method 

 recommended by the Central Rubber Station at Buitenzorg. The 

 degree of uniformity obtained by separate and grouped estates, as 

 shown by charts illustrating the results of tensile tests, was quite 

 remarkable. 



In this the Netherlands East Indies are much in advance of 

 British Malaya, for although the Agricultural Department of 

 Malaya recommends various methods in the different stages of 

 ruliber preparation it does not recoinmcnd any one uniform 

 method, with the result that practically every British estate varies 

 in the method of rubber preparation. 

 Crepes of various degrees of color were shown ; first, a standard 



^The Fisk Far East LimiteH, Singapore, S.S. 



Professor Wyndham R. Dunst.'\n, 

 C. M. G., LL.D., F. R. S., 



\'ice-President, Fifth International Rurees 

 Exhibition 



pale crepe as accepted by tlic market; second, a crepe prepared on 

 a manufacturer's estate for his own use illustrating the disre- 

 gard of dolor. Following this were various "oflf color" crepes, 

 some from improper handling of the coagulant, others from trees 

 tapped after resting, causing the latex to coagulate too slowly — 

 and brown crepes made from lump and scrap. 



.An exhibit of special interest to crude rubber buyers and 

 estate men was the display of several samples of defective crepe 

 and givif.g the following reasons for the defects : 



Coagulation Faults: (1) Streaky crepe caused by oxidation 

 of serum on the surface of the coagulum which was due to too- 

 slow handling of the rubber. (2) Streaky crepe caused by allow- 

 ing partially precoagulatcd latex to stand too long before adding 

 coagulant, also by adding improperly diluted acid, or improper 

 mixing of diluted acid with the latex. 



Faults During Rolling: (Ij Discolored from rolls, (a) 

 Rolls allowed to become rusty — a rare fault, (b) Crepe run in a 

 machine which had been running empty for some time, creating 

 tine iron filings. These are run in the crepe and on second roll- 

 ing become throughly pressed in, causing gray stripes in the 

 crepe. (2) Crepe rontainjng cotton from native's clotliing be- 

 coming entangled in the mills. 



Drying Faults: (1) Slightly streaky crepe caused by un- 

 evenly rolled and unevenly dried crepe. (2) Pink, blue, yellow 

 and green spotted crepe, caused by insufficient drying space, re- 

 sulting in the crepe being taken down before thoroughly dry and 

 lying folded up, which almost invariably causes the developinent 

 of micro-organisms showing in the sniall colored spots so often 

 seen in pale and palish crepes. 



Colored Spots in Crepe: (1) The spots mentioned above 

 sometimes develop in w-et crepe still hanging, and unless the re- 

 mainder of the crepe is removed from the shed at once and the 

 shed disinfected these spots spread throughout the entire lot in 

 a few hours. (2) Red streaks caused by the saliva of a native 

 chewing betel nut. (3) Red discoloring caused by red lead from 

 the pipes during creping. (4) Dark streaks found in lump scrap 

 crepe w-hich has been al!ow-ed to stand and heat, or ovcro.xidize 

 before creping. These streaks often become soft and sticky and 

 gradually spread throughout the rubber. (5) and (6) A clear 

 lump crepe and a red discolored lump crepe (cause not given) 

 which give the same results in testing for tensile strength. (7) 

 Oil-streaked crepe caused by oil from bearings resulting in very 

 uniform vulcanization. (8) Sticky brow-n streaks caused by oil 

 containing copper from bearings. This stickiness will gradually 

 spread throughout all the latex with w-hich it comes in contact. 



An exhibit siinilar to the preceding one displayed the various- 

 defects in ribbed smoked sheets and the reasons for these im- 

 perfections. 



Air bubbles in the sheets are caused by: (1) Insufficient 

 mi.xing of coagulant with latex. (2) Prematurely coagulated 

 latex. (3) Failure to properly skim foamy substance from the 

 surface of the latex. (4) Insufficient dilution of latex causing 

 fermentation of proteins during the drying process vvhicli in turn 

 creates gases resulting in bubbles. 



Dark and light patches in sheet are caused by surface dis- 

 coloration of coagulum. 



Blistered sheet caused by too high temperature in tlie smoke 

 house. 



Sheet containing sand. This is due to the removal of all under- 

 growth as well as dead leaves from estates, leaving bare ground, 

 resulting in sand being blown into the latex cups. 



Barky sheet due to insufficient attention to latex strainers. 



