The Boot and Shoe Manufacturers' Assistant and Guide. / Containing a Brief History of the Trade. History of India-rubber and Gutta-percha, and Their Application to the Manufacture of Boots and Shoes. Full Instructions in the Art, With Diagrams and Scales, Etc., Etc. Vulcanization and Sulphurization, English and American Patents. With an Elaborate Treatise on Tanning.

by Unknown

CHAPTER III.
VULCANIZATION.

Camphine or turpentine, oil of sassafras, and all the essential oils, are faithful tests of the quality of gum elastic, and as certain in their tale-telling as nitric acid is of the genuineness of gold. As the native gums, and also the common manufacture of gum elastic have the same general appearance as those that are vulcanized, more particularly to persons not acquainted with the manufacture nor judges of the goods, these tests are of the utmost importance, not alone to determine whether the goods are genuine, but also to ascertain whether those that are vulcanized are properly done. When these tests are applied to any fabric of native gum, it is rendered very adhesive, and so quickly as to destroy any light fabric almost immediately, while upon goods that are well vulcanized, they should have no such effect. If they do so the manufacture is bad.

Although the manufacture of hard India-rubber goods, by the process of vulcanizing, is extensively known and appreciated in the United States, and in France and Belgium, very little appears to be understood in Great Britain. Indeed, in Birmingham, which is justly termed the “work-shop of the world,” little or nothing, or if anything, a something amounting to a misunderstanding, would comprise the quantity of intelligence upon the subject. There can be little doubt, however, that as the infinite capabilities of the material become known, and justly esteemed, and its amazing applications get manifested, no one thing of late years, surprising as the changes have been in that neighborhood, will have caused so great a revolution in very many of the staple manufactures of that town as will the introduction of this discovery.

As regards the power to be used in the manufacture, steam has a decided advantage over water, as in the plastic state of the mass there exists a variety of proceedings, according to the nature of the material to be made or the object to be imitated, in which steam would have to play a conspicuous part. But it must be in this country as in America and elsewhere, that as the manufacture extends, so will the best and most suitable machinery and power be devised and rendered subservient to its development. When the manufacture is favored with the advantages of steam power, and large capital, the most profitable results have been and are attendant upon it; and perhaps there are few manufactures which require less comparative space, and in which less waste is consequent. There should not be a particle of the substance lost, as all cuttings, sweepings of the factory, and the very dust upon all things around, can be re-worked with profit and advantage. Indeed, it is here that we should make publicly known the fact that every article of vulcanized India-rubber, bears its value according to its make and kind, however old it may be.

As a general impression exists that India-rubber when once vulcanized cannot be again used, this statement should be borne in mind, and the greatest publicity given to it in order that the millions of pounds now lying waste in the shape of galoshoes, &c., may not be heedlessly thrown away. The old Jew clothesmen will at once open their eyes to the fact, and the valet or humble servant girl will find in their collection and sale an increase to their perquisites, in proportion to the consciences of those with whom they deal.

Here, then, we have important elements of economy, at the very beginning and end of the manufacture, if end that can have which has the attribute of a renewal of usefulness. Galoshoes may be called in as worn out sovereigns and shillings are now, and returning to their mint, be melted up and re-stamped for renewed circulation. Another advantage in the manufacture is, that the same tools are employed for its various branches, and the same operatives can be turned from the making of one description of an article to another, without delay or expense. A girl, for instance, who may be engaged as the maker of garments one day, may become the next a trunk, a harness, or a shoemaker; and on the third, find herself occupied in pressing out of the soft and ductile mass brooches, and other articles of adornment, which being afterwards vulcanized, and thus rendered almost imperishable, may serve to encircle the neck, clasp the arm, or hang pendant from the waist of Britain’s fairest daughters. The machinery employed in the manufacture of India-rubber, since the first attempts to work it, has been subjected to variation and gradual improvement. Numerous expedients and divers machines were early tried for chopping, grinding and spreading the gum, and also for flowing it in a liquid or semi-liquid state, which have been abandoned. It is now generally agreed by manufacturers in this business, that the machinery is as near perfection as can be attained; that is to say, they are all satisfied with it. But in this age of improvements, we might see to-morrow one machine doing the work of two or more, and all calculations as to perfectibility obliterated, but to begin again upon fresh data. It must however be admitted that it is of the most simple kind, doing the work well and with astonishing rapidity, although requiring great mechanical power, owing to the toughness and tenacity of the gum. The machine used for cutting and washing the gum is the same as that employed by paper-makers in cutting rags. A large proportion of the India-rubber was nearly useless from the quantity of bark in it until this engine came into use. Gum-elastic or India-rubber can be readily mixed or combined with almost every other substance. It may be mixed with other gums, oils, coal-tar, carbon, and with the earths, and oxides or pulverized metals or ores. It can likewise be combined with all fibrous products.

It is compounded in the manufacture with many of the above substances, for the purpose of obtaining particular advantages for special uses. Ground cork and other light materials are sometimes mixed with the gum to increase the bulk, and make the articles light. The oxides of metals, their filings and pulverized silicas will give imitations of marble. The fibre of cotton, or the dust of different woods will afford simulations of wood of greater or less gravity, as may be required. The combining of plumbago gives the crayon; oxide of zinc, produces lithographic stone, and so on, and on. Pigments and earths are used for color and cheapness, and to increase the weight of the fabric as in the case of carpeting. Bitumen and rosin are sometimes used to give articles a finish, or high lustre. Oxides of some of the metals are used, but white lead and litharge are commonly preferred. From two to four ounces of either of these metals to the pound of gum cause the articles, and particularly those that are thick or massive, to be readily changed or vulcanized, and more completely, or with greater uniformity. Sulphur is applied through the medium of heat in different ways, according to the nature of the articles or fabrics, and their uses. It is generally mixed in the process of crushing or grinding the gum, in the proportion of half an ounce of sulphur to the pound of gum for the vulcanized elastic goods, and about five or six ounces to the pound of gum for the “vulcanite,” or hard goods. In the former case, about 270° of heat are necessary, and in the latter, 300 to 310°. At other times the sulphur is dusted upon the articles in the form of flour of sulphur before they are placed in the heater or oven. This is commonly done in the manufacture of elastic thread and other articles, which possess no extraneous mixture, in which case the gum is penetrated or impregnated with the sulphur, without its being mixed with the gum in the crude state.

Enough has been given in this chapter to permit of the intelligent and thoughtful at once following us, in the manufacture and finish of—we will say for example—buttons. The mass in a tough but plastic state, a toughness and plasticity in combination with which there exists no approachable parallel—having been so rendered by simply plunging it into boiling water, becomes of as easy manipulation as clay. Indeed the material in this stage being so like clay, we can scarcely point to any better illustration than the porcelain button manufacture, which being familiar to most, there can be no need to detail. Treated thus like clay, the moulds may be filled by the gross, and the buttons afterwards submitted to vulcanization. The moulds may bear any impress, and however fine such patterns may be, the material will receive and retain them after vulcanization, to a degree which will defy every power that destroys all other substances short of those of actual cutting, filing, or grinding. Thus a button is produced at an extraordinary economical rate, and with marvellous ease, which, while comparing the facility of its origin to that of the porcelain, possesses the superlative qualities of being comparable with one made with the properties and strength of iron or other metal, and in imitation of bronze, ivory, cameo, and is, indeed, a substitute for any other, and the very best material or thing ever used for button making. In a word, it may possess the closest similitude to the most exquisite carving, with the properties of bronze, ivory, or any hard and scarce material. The applications as far as results are concerned, are attended with like favorable characteristics, whether the article produced be nearly every one of those innumerable and familiar things, which meet us at each turn, either within the palace or cottage, or the many others to be met with out of doors.

CHAPTER IV.
VULCANIZATION.

The importance of the improvements in gum-elastic for educational purposes, has been previously commented upon in previous portions of these notices, and we would now give a little additional space to some of the many purposes in this direction, which assist in filling up the almost infinite measure of the uses of vulcanized India-rubber. Much has been done to perfect them, but enough has already been accomplished to prove that the causes of education will hereafter be promoted by the use of many articles made of the vulcanized fabrics. The cheapness of some of these articles, compared with the cost of those of other materials, gives double assurance of the correctness of this view. The expensiveness of globes, for instance, which are admitted by all to be by far the best means of imparting and obtaining geographical and astronomical information, has rendered them accessible to few persons, either pupils or teachers. The adaptation and application of gum-elastic to these purposes, will bring within the reach of every youth in the commonest school, a perfect globe, at a price within their means, and maps more durable than leather or parchment, at cheaper rates than paper maps are now made when mounted on linen.