Buy … New Zealand Goods and Build New Zealand
New Zealand Industries Series
No. 13. Rubber Goods.

By O. N. Gillespie

The antiquarian of the year 2940 will pore over many perplexing puzzles in the history of the last few hundred years of our era. None will be more baffling to him than to find the reasons why such long gaps existed between the first discovery and the utilisation of materials which are in universal use to-day. There are many examples, but the strangest of all is rubber. Columbus, looking for the Indies in his tiny caravel, records among the marvels of the new lands he found, that Indian youngsters possessed a unique type of plaything. It was a ball made of a black substance that had the magic property of “springing up when thrown down.” Being a scientifically-minded person he did not immediately ascribe the phenomenon of the bounce to witchcraft, but found that these apparently animate objects were made from the gum or sap of a tree that occurred in abundance.

Centuries went by, and gum elastic, as it was known, remained a curiosity. Far on in the nineteenth century a few toys and pencil erasers represented the uses of this commodity which even took its very name “India-rubber” from one of these.

To-day the world consumes annually 700,000 tons of rubber, and modern comfort and transport, and, indeed, the methods and the arts of modern life would be impossible without it.

New Zealand manufactures its own rubber goods on a scale which will astonish readers, however accustomed they may be to startling surprises in the progress of New Zealand industry.

Railway Publicity photos.

It was a far cry from Columbus and the Bahamas to Kew Gardens, London, and it is still farther from the great English botanical museum to the Great South Road at Penrose, Auckland. Yet the seedlings from Kew Gardens made the great Reidrubber factory in this country possible, and, incidentally provided more than a hundred Auckland citizens with a useful avenue of civic progress. This fine modern establishment covering nearly 40,000 square feet is a revelation of what can be done in the way of industrial expansion. The plant is up-to-date in every respect, and there is an atmosphere of scientific precision and forthright endeavour which is noticeable at once.

Mr. G. W. Reid is the pioneer of the rubber industry in New Zealand, his lifetime having been spent in its study. The romance of rubber is a tale of wonder. For centuries, it was a scarce commodity, enormously difficult to win from the far tropical wastes where the trees flourished. It was costly and apparently not of any great utility. In the age of exploration, however, “Caoutchouc” was found growing in many parts of the world. After the discovery of vulcanisation, its uses multiplied rapidly, and the search for rubber became feverish. The Brazilian Government jealously guarded the plant, but an enterprising English traveller, Sir Henry Wickham, smuggled some seeds to England. From seedlings carefully nurtured there, the great Malayan plantations grew.

Hydraulic steam-heated presses at the Reidrubber Factory, Auckland.

To-day, practically all commercial rubber comes from scientifically-plannedand-operated plantations, although as recently as a quarter of a century ago, most of it grew wild. The British Empire controls 60 per cent, of the world's plantations, and the Dutch 37 per cent., leaving a small margin for the rest of the world.

I listened as I went round the Reidrubber establishment to the explanation of the wonder properties of rubber. “Caoutchouc” is a combination of hydrogen and carbon. It is impermeable by water or gases; it is tenacious and elastic; it is always in a state of callous chemical lethargy, repelling all invaders through sheer invulnerability; it is not affected by exposure to the air; it refuses passage way to electricity; it is soluble in certain essential oils; it wears better than steel.

Yet, raw rubber is practically useless. Crepe soles for shoes and a few odds and ends of negligible uses would have been as far as it could go until vulcanisation was discovered. Goodyear in America and Thomas Hancock in London, round about the year 1840, were responsible for this new foundation of modern civilisation. It was found that by adding sulphur and other ingredients and subjecting the mixture to intense heat, rubber took on a vast range of new values. It can become hard and still flexible like horn, or it can transform itself into the black solidity of vulcanite. “All the way from garter elastic to an ebonite jewel box” was the way it was explained to me.

Rolling the rubber sheets at the Reidrubber Factory.

Under the wizardry of this process, I saw rubber turning into widely differing forms. There is the brick-hard rubber which encases battery cells full of acids; there is the sponge rubber of a theatre chair or toilet sponge; there are the tenuous transparencies of party balloons, the everlasting cycle tyre treads, the pliable garden hose, and a hundred others from rubber pavements to tennis balls. A visitor from Mars would think them to be made of totally dissimilar substances.

A rubber factory in some ways resembles a huge bakery in which the chemists are the chefs. The recipes are as varied as those used in a first-class hotel kitchen for a commemoration dinner. Compounds of strange and wonderful ingredients are put in with the raw rubber, every one of them, as with the family Christmas pudding, the result of experience and knowledge. The atmosphere is heightened in its resemblance to an enormous cookhouse by the baking processes which follow later, and the general glow and heat.

The raw rubber arrives as “latex,” turned from the milky fluid that runs down the tree trunks, to thin reddish brown sheets, rather like smoked fish in tint. These bear no more resemblance to what they will become than flour and spice do to the finished wedding cake.

The first process is mixing. Huge mechanical mixers, rather like enormous mechanical washing plants, revolve the raw rubber, along with the additions of chemicals, pigments or whatever else has been found necessary to provide the right textures, colours or consistencies.

Out of the maw of these huge mechanisms comes a substance resembling dough except that it has many hues. It seems heavy, and no ordinary housewife would expect it to rise. Yet sponge rubber is made by a process very similar to the use of baking powder in scones. Certain chemicals, when added, liberate gases which fill the interstices in the solid rubber, and give the sponge effect.

One of the fascinating sights at Reidrubber are the rolling mills. Never was dough subjected to such a thorough rolling. These gargantuan cylinders are revolving at different speeds, so that the maximum efficiency is obtained.

Soon the rubber is ready for its various destinations. Masses are stored of red, grey, white, and a host of colours made possible through latter-day discoveries in fast dye colourings.

“Cooking” at Reidrubber—a constant process in rubber manufacture.

In this state, this rubber dough could be dissolved by petrol, would go softer if subjected to heat, but it is all of a marvellous plasticity. It can be given any shape or mould. If a garden hose or rubber tubing is to be made, a complicated machine called an “extruder” is used. It works by forcing the plastic rubber through an orifice the exact size of the required tubing.

Before any of the materials are placed in the way of taking their required shape, a series of exhaustive tests as to content and quality are applied. Then the vulcanising processes begin their weird work. The distinctive feature of a rubber factory is that everything is finished with heat. The odours of brimstone and roasting rubber have a tang of their own, and are all-permeating but not unpleasant.

It would take the space of three articles to describe the full number of distinct processes to turn out the full range of Reidrubber; bath mats, cycle tyres, hot-water bottles, vulcanite goods, jam jar rings, tennis balls, washers of every conceivable size and kind, insulators, plugs, cushions, garden hose, tubing, are some of them.

Perhaps the most exciting and important for us is the complete set of milking machinery rubber parts. I stress this not because I saw letters from dairy farmers giving examples of incredible lasting qualities of Reidrubber parts, but because the company has a big export trade in this specialised line. I have stressed more than once that there is no reason why our secondary industries page 52 page 53

Bicycle tyres in process of moulding at the Reidrubber Factory.

should not vie with our primary products in supplying overseas markets. Here is an example: New Zealand definitely leads in the mechanisation of milk production. The special knowledge obtained through practical experience over a wide area, years of costly experiment and research, and close acquaintance with the local working farmer's problems in the milking-shed itself have placed Reidrubber in a unique position, and the result is nationally worth while.

I found the making of cycle tyres a fine example of high pressure vigilance in testing and of modern exactness of manufacturing processes.

The first step is the mingling of cotton with rubber in solution. This becomes one indissoluble fabric which is then cut into long narrow strips which fit over two hoops of steel wire. An uncanny machine then covers this skeleton with layers of tough rubber “dough” so that the mould can be made with the most abrasion-proof material outside. Thereafter, as always, the vulcanisation takes place. It is curious to reflect that the world's transport owes so much to a Dublin “vet” fitting a garden hose to his boy's toy bicycle. It is impossible to visualize the modern world without the pneumatic tyre.

Another complex mechanism encountered on the way to the cycle tyre department, was the one which tests and records the tensile co-efficient of each length of rubber. It stretches the material out, and I saw it reach to seven times the original length. Each batch undergoes this and other searching tests.

I should explain that as with so many other things described in these articles, the shaping instrument is the press. Here, however, there are differences; there is slow relentless hydraulic pressure, not a heavy blow, and there is always the accompaniment of steam or other heat. The methods are so contrived that vulcanisation takes place during the use of the die or mould.

The making of tennis balls is an intriguing process, possibly the best panorama in the whole factory. Reidrubber supply all the tennis balls for one of the largest associations, so that we can accept the production system as of high standard.

Specially prepared “dough” is placed round a steel ball and “cooked.” The rubber flows round the steel globe and settles into perfect shape and even thickness. Next, the problem is to get the completed thin rubber tennis ball away from the steel sphere it encloses. There is only one small hole, and more folk than George III would be completely baffled. With quite dramatic effect, a soft “pop” sounds and the ball is exploded from its host, the force being applied from inside by a pneumatic blower. The hole seems quite intact, and is promptly plugged with a small rubber solid cylinder. Once more a baking process is applied, the completed ball is inspected for flaws, and is now ready for the coat. The wool-felt covering with its familiar symmetrical jig-saw pieces, shaped to fit perfectly, is stamped out by presses. The coverings are coated with rubber stickfast solution, placed in position, and once more heat is used to iron them on. This container has a revolving wheel, and the nap is brought up by more heat. Then the tennis ball has to present itself for a series of matriculation tests. It goes on a check measure for size, and is tested on fine measure scales for weight. Lastly it is tested for bouncing qualities. It is released from a trap chamber, and its bounce is measured exactly by indicators placed on the wall. What amazed me was the trifling “too much or too little” that entailed rejection.

Toy balloons in the making at Paratex, Wellington.

In some cases, notably in the re-tread manufacture, triple cooling processes are used. It is easy to understand the need for this, as hard wearing is a requisite for this type of rubber article.

As a result of my journey through Reidrubber's modern home, I am satisfied that New Zealand can make anything in rubber demanded by our own people.

The progress made in a few years by this New Zealand-owned and managed institution has been rapid, but it will grow faster yet.