Asbestos: What it is and where it’s found
There is probably no production of inorganic nature about which there is so much popular mystery and misconception as asbestos. It is vaguely understood that the principal claim of this remarkable product to attention is that it cannot be consumed by fire. Not infrequently, the effect of the mention of asbestos is to carry the hearer back to the days when the people of the pharaohs wrapped their dead in cere-cloths woven from the fibre, in order to preserve them, the body having been first embalmed.
Romantic stories have also come down to us of ancient demonstrations of magic in which asbestos has played the leading part, but the real interest in asbestos centers in the present. It is of more importance to the human race today than it has been in the whole range of history.
Asbestos twenty-five years ago was practically not known in the laboratory of the chemist or mineralogist. It now finds its way in one form or another into every workshop where steam is employed.
To the question, “What is asbestos?” It is not altogether easy to and an answer. Geologists classify it among the eornblendes. in itself, asbestos is a physical paradox, a mineralogical vegetable, both fibrous and crystalline, elastic yet brittle, a floating stone, but as capable of being carded, spun and woven as flax, cotton or silk, it is apparently a connecting link between the vegetable and the mineral kingdom, possessing some of the characteristics of both.
In appearance it is light, buoyant and feathery as thistledown; yet, in its crude state, it is dense and heavy as the solid rock in which it is found. Apparently as perishable as grass. It is yet older than any order of animal or vegetable life on earth. The dissolving influences of time seem to have no effect upon it. The action of unnumbered centuries, by which the hardest rocks known to geologists are worn away, has left no perceptible imprint on the asbestos found embedded in them.
While much of its bulk is of the roughest and most gritty materials known, it is really as smooth to the touch as soap or oil. Seemingly as combustible as tow, the fiercest heat cannot consume it. and no known combination of acids will destructively affect the appearance and, strength, of its fibre, even after days of exposure to its action. It is, in fact, practically indestructible.
Its incombustible nature renders it a complete protection from flames, but beyond this most valuable quality, its industrial value is greatly augmented by its non-conduction of heat and electricity, as well as by its important property of practical insolubility in acids.
Where asbestos is found
Asbestos has been found in all quarters of the globe. It comes from Italy, China, Japan, Australia, Spain, Portugal, Hungary, Germany, Russia, The Cape, Central Africa, Canada, Newfoundland, this country and from South and Central America.
The asbestos generally found in the United States, especially in Virginia, the Carolinas and Texas, also in Staten Island, New Jersey and Pennsylvania, is in appearance like fossilized wood. The veins range in length from a few inches to several feet. The fiber can be split off like soft wood, the appearance being woolly, and when separated, it has no strength or cohesion. It cannot be spun nor even pulped. At one time it was thought it might be profitably used as a filler in paper-making, but actually it is of no commercial value.
Notwithstanding this wide distribution of asbestos, the only varieties which at present appear to demand serious consideration, from a commercial point of view, are the Russian, the South African, the Italian and the Canadian. The principal claim possessed by the Russian fiber to a place in this quartet is based on the enormous extent of the deposits which have been discovered In East Russia, beyond the Ural mountains, and Russian Siberia. So far, their specimens have been of comparatively poor quality. The yield is used almost entirely in Europe, where lt is mixed with the Canadian for spinning, making taper and other purposes where an inferior grade can be utilized,
Before the development of the Canadian fields, the Italian asbestos was supremo in the market. For nearly twenty years, Italy has been looked to for the best trades of the fiber. From a point in the northern mountain slope of the Susa valley is taken the floss asbestos fiber, the appearance of which in gas stoves is so familiar. In the same locality is found a fine white powder of asbestos, which serves for paint and other purposes. The mining is carried on at a height of from 6000 to 10,000 feet above sea level.
But the Italian asbestos industry, once so important, is already on the downgrade. The difficulties of mining are very great, and unduly increase the cost of production. The asbestos itself, judged by the latest standards, is of inferior quality: it is not easy to spin, and it does not pulp well in the making of paper. The best grade is extremely from the Italian mines is rapidly falling off. As a matter of fact, Canada contains the great asbestos region of the world, in the sense that while its mines are practically unlimited in productive capacity, the product is of a quality which fully meets the requirements of the newest and most exacting of the innumerable uses that are daily being found for it.
The process of manufacture is intensely interesting, more especially from the fact that as the industry is constantly entering upon novel phases, new methods of treatment and special machinery have to be devised. One of its special uses is for wall plaster.
This in a new application which will have a distinct effect in modifying the practice of indoor plastering. Instead of the ordinary tedious and elaborate preparations of studs and stips, and the use of inferior and dust-creating mortar with its after-scoring (which is necessary to give cohesion to the final coat of plaster of Paris), a single coating of the asbestos is laid on. it has a glossy surface that will not crack, as while firm, it is perfectly flexible. It can be put on the raw brick; and a room of which the walls have been built in the morning can, before night, have a smoothly finished interior surface — shining like glass and as hard as a rock.
A kindred application of asbestos is now coming into vogue in the shape of inflammable decorations for walls and ceilings. These are used a great deal for the saloons of steamships. They are embossed in very beautiful designs, and can be treated with gold, varnish, lacquers or any other substance for the enhancement of their ornamental effect.
Firemen clad in asbestos clothing and masks, as are those of London and Paris, can walk through the hottest flame with comparative impunity. Asbestos fireproof curtains have reduced the mortality of theater fires in a very appreciable degree. In torpedoes, the difficulty of dealing with the charges of wet gun-cotton is overcome by enclosing them in asbestos, the employment of which has also, in a great measure, brought the dynamite shell to its present efficiency. Asbestos is made into a cloth available for aeronautical purposes. A balloon made of this inflammable material escapes one of the most terrible dangers to which an ordinarily constructed balloon is liable.
In buildings and other construction
Probably one of the first applications of asbestos in this country was to roofing. To buildings covered with this material, the shower of sparks from a neighboring conflagration involves no danger. The fact that woodwork can, by its use, be made inflammable has come to be an important factor in the insurance of buildings.
One of the largest branches of asbestos manufacture is that of sectional cylinders for pipe coverings; for retaining the heat of steam and other pipes; felt protective coverings for boilers; frost-proof protections for gas or water pipes; and cement felting, which can be laid on with a trowel for the covering of steam pipes, boilers or stills. In some of these cases where it is only necessary to retain the heat, the asbestos is mixed with other substances; but where the protection must be fireproof as well, only asbestos is used. The utility of such covering is well-illustrated in the heating system of railway cars. The main pipe from which the individual cars draw their respective heat supplies by side mains would lose a large proportion of its caloric from the rapid motion of the cars through the air.
More uses for asbestos
An interesting innovation in this class of manufacture is asbestos sponge. It is not generally known that sponge has great power of fire resistance. The discovery was made accidentally not long ago, and the result was that a consignment of scraps of sponge picked up on the southern coasts was ordered for experimental purposes. The sponge was finely comminuted and mixed intimately with asbestos fibre. The combination was found so successful for any covering which had to be fire-proof as well as heatproof that the material has become standard. Being full of air cells, it necessarily makes an excellent non-conductor.
Another very extensive department in asbestos manufacture is that of packings. Of these there are an infinite number of forms. In these days of high-pressure and ocean records, it is of supreme importance to marine engineers that they should have jointing and packing materials upon which absolute reliance can be placed. In order to meet modern exigencies, every possible form of packing has been constructed, particularly with asbestos and metallic wire, and with asbestos and rubber cores for gland packing. The making of asbestos paper varies from the building up of the thickest millboard to the production of writing paper which, from its indestructibility, is invaluable in case of tire for preserving charters, policies, agreements and other important documents.
To the electrical engineer, asbestos is absolutely indispensable. Many parts of electrical devices and machinery and wiles through which the electric current passes become heated, and were it not for the electrical insulation and heat-resisting qualities which asbestos possesses, the apparatus would be completely destroyed, particularly in the case known to electricians as “short circuiting.” For such purposes, it has been found advisable to combine asbestos with rubber and other gums, and this combination is now used universally for not only electrical, but also steam and mechanical purposes.
A considerable part of an asbestos factory is devoted to weaving, the asbestos being first drawn into thread for that purpose. Here again is an apparently endless diversity. There is the fireplace curtain-blower, which, with an auto matte spring-rolled attachment, takes the place in the frame of the fireplace of the less sightly sheet-iron blower; and filtering cloths for many purposes, from straining molten metal to clarifying saccharin juices in beet-root-sugar refineries. A cloth is made for straining and filtering acids and alkalies in chemical laboratories. This is specially useful when the liquid to be treated is of a caustic or strongly acid nature. The filter can be thrown in the fire, and after the residual matter has been consumed the web is as good as new. For filtering purposes, generally asbestos has a unique adaptability, and in tropical countries it is held in grateful estimation as a cooler and purifier of water.
The newest departure in the asbestos field is the construction of electrothermic apparatus. The heating effect of the electric current is utilised by embedding the wire in an asbestos sheet or pad. The pad is used by physicians and nurses for maintaining artificial heat in local applications, and Is said to be already largely used in hospitals. Another application of the same principle is to car heaters. A sheet of asbestos, with the embedded wires, is clamped between two thin steel plates, and the portable heater thus provided, or a series if need be, is connected to the car circuit quickly and easily. It gives an even and healthy heat, and can be so regulated as not to overheat the car.
– George Heli Guy in New York Post
Top photo: Miners at an asbestos mine in Black Lake, Quebec, 1895 – via Musée minéralogique et minier de Thetford Mines. Ad from The Houston daily Post, October 4 1896