USES OF ASBESTOS
Asbestos is useful because of its incombustibility, insulating qualities, and fibrous structure. High-grade asbestos is spun or woven into ropes and fabrics, the fabrics being used for many purposes, such as safety curtains, mats, mattresses, upholstering, firemen’s suits and gloves. Of late years much high-grade asbestos has been used for friction facings in brakes and for packings. Low-grade asbestos is used for a great many purposes, which may be classed in three groups—building, insulating, and miscellaneous.
For building purposes asbestos is employed in many ways. A mixture of asbestos and cement is used to make fireproof shingles or slates. Asbestos is also used with Portland cement to make a protective surface on metal sheathing; asbestos paper is used for weather and sound proofing and also for fire-protection purposes. It is used widely for plaster, which not only is fireproof but also improves the acoustic properties of auditoriums, churches, etc. Asbestos is also used for floor tiling and in the manufacture of paints. Asbestos lumber and millboard are employed for many structural purposes.
Asbestos cement, a mixture of asbestos fiber and clay, is much used as a covering for boilers and steam pipes to prevent heat radiation. Other coverings are made from a mixture of asbestos and magnesia. Varieties of asbestos having a low iron content are useful for electrical insulating purposes.
Some of the many miscellaneous uses of asbestos are for fire brick, acid filters, lead-fume collectors, stove mats, cooking-utensil linings, etc.
The most essential of the above uses are those in which the long-fiber asbestos is employed. For fireproof ropes and fabrics nothing can take its place. Its use in friction facings for brakes is essential in all motor vehicles.
The uses for which low-grade asbestos is employed may be regarded as less essential and might be eliminated in case of necessity, though such elimination would no doubt involve many serious difficulties. Fire risk would thereby be increased and many boilers and heating plants would be rendered less efficient and more wasteful, though these difficulties could be overcome to some degree by the use of substitutes.
Substitutes.
—Slag wool or mineral wool is a fireproof material and a good non-conductor of heat and sound. It is also highly porous, and hence it is useful as an absorbent. It can, therefore, be used to some extent as a substitute for asbestos for heat insulation and fireproofing. However, as it is brittle and cannot be woven as readily as asbestos, it is not to be regarded as a satisfactory substitute for the higher grades. Talc may be employed in the manufacture of fireproof and corrosive-proof paints, and also as a lining for furnaces and fireplaces. Infusorial earth is used to some extent as a substitute for asbestos for insulating and fireproofing. But it is important to note that none of the substitutes mentioned above can replace the high-grade spinning fiber.