Borate glasses have a more complex action of

alkali In chemistry, an alkali (; from ar, القلوي, al-qaly, lit=ashes of the saltwort) is a basic, ionic salt of an alkali metal or an alkaline earth metal. An alkali can also be defined as a base that dissolves in water. A solution of a ...

ions than

silicate glass Glass is a non-crystalline, often transparent, amorphous solid that has widespread practical, technological, and decorative use in, for example, window panes, tableware, and optics. Glass is most often formed by rapid cooling (quenching) of ...

es. Borate glasses also have major differences in their optical properties. The single largest use of boron compounds in the world (accounting for half of total global use) is the production of certain types of boron-treated

glass fiber Glass fiber ( or glass fibre) is a material consisting of numerous extremely fine fibers of glass. Glassmakers throughout history have experimented with glass fibers, but mass manufacture of glass fiber was only made possible with the inventio ...

for insulating and structural

fiberglass Fiberglass (American English) or fibreglass (Commonwealth English) is a common type of fiber-reinforced plastic using glass fiber. The fibers may be randomly arranged, flattened into a sheet called a chopped strand mat, or woven into glass cloth ...

. In these uses the boron may be present as borax or boron oxide, and adds to the structural strength of the glass as borosilicate, or is added as a fluxing agent to decrease the melting temperature of pure

silica Silicon dioxide, also known as silica, is an oxide of silicon with the chemical formula , most commonly found in nature as quartz and in various living organisms. In many parts of the world, silica is the major constituent of sand. Silica is one ...

, which is difficult to extrude as fibers and work with in pure form, due to the high temperatures involved.

References

{{Glass forming Glass