"DUNLQP'S"

Dominion, Volume 9, Issue 2579, 29 September 1915, Page 16

"DUNLQP'S"

ACCEPTED NAME FOR QUALITY JN RUBBER GOODS ' How little does the general publi6 know of rubber awl tho manifold uses to which it is applied! Ono lias only to talk tolMr. J. B. Brinsden, manager ih New Zealand for tho Dunlop Uubber Co. of Australasia, Ltd., and -maybe take a. ten minutes' run over the company's showroom, warehouse, and factory, to realise the ■ general ignorance that prevails 011 'the subject..: In a : vague'kind of way .people--know ''that Dunlops mako tires and hose and tul> ber heels, but thoy hardly -comprehend the vast assortment of, gocds. that are being marketed by this-. great, firm, which has its New Zealand headquarters in Courtenay Place. There in tho space of a few minutes Mr. Brinsden' ,ivill show huge stocks of nibbeiVtires for motor-cars, motor , vehicles (solid), motor cycles, bicycles, l carriages and buggies, and within theso heads are a wonderful variety of weights and patterns. -There is one tire i'or which the demand never ceases, a motor tiro shaped as though a piece of tho face-had been neatly scooped out transversely. Tho average person believes that to bo a non-slipping device. It is >to 6ome extent, but its technical purpose is to provide' space for displacement. That is to say, that when a weight is applied to a tire it does not compress the rubber. That is not possible. The rubber is simply-displaced— stretched,, flattened out, or lengthened. Tho nick/out of the tiro is for that displacementit gives tho face of -tho tire : room to work. - Then, there are mountains of liose, plain or coloured, ribbed, armoured, air hoses heavily armoured with closecoiled wire capable of -withstanding a pressure of 30001b. to the square inch (used in hydraulic cranes), garden hose, suction hose' for irining and genera engineering purposes, and wonderful rubber conveyor belts up to 3ft. in width. In other portions of the warehouse are stocks of Vubber heels, gloves, teapot spouts, wasters, and a hundred and ono things that 0110 forgets as soon as the eye deserts tliem. One steady line made by Dunlops are for., rubber- rings for ... hermetically-seal-ed tjns of jam and _ conserve, rubber mats; and substantial rubber edges for steps. In tho factory'are vulcanising plants, and devices for putting solid rubber tires 011 wheels .(with' an electric welding plant to make the job a neat one). Here one may also see the process of building up those hard white rollers seen on wringers—built up carefully from pure,sheet rubber, and vulcanised into solidity without loss of a certain elasticity. In this interesting factory, too, motor-tires are-lialf-soled and heelfd with neatness and dispatch;

What is Rubber? And wliat is rubber? Mr.Brinsden can best answer tlio question comprehensively.' It is, lie - says, the dried, coagulated milky juice obtained from many trees and shrubs that grow. the tropical parts'of: America, Africa, Asia, and the East Indian Islands— chiefly in America., from a tree' bearing| the botanical na'mo of Henea Brasilien-1 sis, which flourishes ■in ■ the stormy I valley of tho Amazon. It is tapped by! a herringbone cut in the bark, made in August and February, the outflow being then of the consistency of milk. Each tree yields about six in three days, but less than half of that coagulates into rubber. ■ The collected juice Jvaving been conveyed to a convenient station, is poured into a larger vessel. To obtain the rubber, a broad polo or paddle is dipped in tho juice, a thin coating of which adheres. The paddlo is then turned round and round in the white vapourfuming from certain oily palm-nuts heat- 1 ed in a pot. Each layer of'rubber allowed to become dry ahd.firm before adding another. Repeated dippings soon increase the size of the lump._ A practised hand can makonive or six pounds in an hour. From whatever cause the rubber thus prepared is the finest that can be obtained. 'When the lump is big enough, it is cut off the paddlo with a wet knife,'and tho "biscuits," as they are called, 'are sent to irfarket. ■; When the rubber reaches tho manufactory, the lumps are first softened by the prolonged action of hot water, and then cut into 1 slices, usually by hand, so that any., largo stones or other foreign bodies can be removed. It is then further washed -and. masticated (chewed to pieces) by grooved and barred rollers working in running water, till all impurities tare carried away, and tiie rubber comes out in sheets about three: feet wide, like brown crepo.

Vulcanisation of Rubber. The sheets of masticated rubber, after being dried, are next, taken to the mixing rollers, where," by • tho addition of a certain,percentage of sulphur and any colouring matters • required, they aro made ready for 'vulcanisation. Rubber is mainly vulcanised by being subjected for half an hour or more to a heat of up to 150 degrees centigrade in closed iron vessels into which high pressure steam is admitted. According to the article desired, so the manner of its insertion in tlio vulcaniser varies. Calendered sheets -arc generally cured between folds' of wet cloth. Tubes are sometimes wrapped in wet clotlis around a bar or-mandrel, or are embedded in pulverised French chalk, which supports thorn, and keeps 'their shape. Many articles aro formed in iron moulds, the rubber being closoly stuffed into them and the heat swelling ' tlio rubber into the shape of tho mouTd, whose form it retains on cooling. Tires are generally moulded. Articles of very thin -rubber are vulcanised by being liung in a load-lined chamber in the fumes of chloride of sulphur. • . Tho effect of vulcanisation, as it is called—being the combination of sulphur with and tho application of .-heat to rubber—is to render it more useful for most purposes than in its uncured state. It will stand a greater heat without softening or melting, and ,is not made so hard; brittle ;and inelastic b.v cold. Nor do liquids such as naphtha, benzine, or carboivdisulphid® dissolve it' as tliev do in its unvulcanised condition. It will also withstand all but the most powerful acids. Rubber .deteriorates rapidly under-tho action of oil. Sunlight. eventually destroys its valuable properties. A, tour through tho Dunlop Rubber Company's big works at Montague, Melbourne, 'is a liberal education. It is one of tho largest manufactories South of the Lino, employing about 1400 hands ever busy turning, out multitudinous rubber goods for the people of_ Australasia. No one who takes a trip to Melbourne should 'inis?. seeing these fine works.