Flint Glass vs. Borosilicate Glass
Common glass in its purest form consists mainly of silicon dioxide (SiO2), a compound found in large quantities in sand and quartz. On the molecular level, the SiO2 molecules are randomly positioned-that is they lack any type of orderly pattern, crystal lattice or matrix. This amorphous solid is produced by super-heating solid SiO2 to form a molten state and then rapidly cooling it. The physical properties of glass can be modified by mixing numerous materials with the solid SiO2 before super-heating it.
"Flint" glass is usually composed of either lead or potassium silicate, which simply means a combination of silicon dioxide (SiO2) with lead or potassium. This blend creates a relatively high refractive index and high degree of light dispersing power compared to other types of glass. As a result, this blend of glass is characterized by its brilliance and luminosity. This property makes flint glass especially desirable in the production of lenses, optical instruments, prisms, and ornamental glassware. The name "flint" is derived from the mid 17th century process of grinding flint stones into a fine powder from which silica was obtained.
"Borosilicate" glass is manufactured by adding boron to silicon dioxide (SiO2). This produces a blend of glass that is abnormally durable relative to other types of glass. Specifically, it withstands much more physical, chemical, and temperature stress without detriment to its own structure than common glass. As a result, borosilicate glass is highly utilized in laboratory and kitchen settings. Brand names such as Pyrex, Borosil, Simax, and Bomex are all borosilicate.