Silica fibers made of sodium silicate (water glass) are used in heat protection (including asbestos substitution) and in packings and compensators. They can be made such that they are substantially free from non-alkali metal compounds.
Sodium silicate fibers may be used for subsequent production of silica fibers, which is better than producing the latter from a melt containing SiO2 or by acid-leaching of glass fibers. The silica fibers are useful for producing wet webs, filter linings and reinforcing material.
They can also be used to produce silicic acid fibers by a dry spinning method. These fibers have properties which make them useful in friction-lining materials.