page_title: Glass
section_title: Borosilicate
hierarchical_section_title: Glass / Types / Silicate / Borosilicate
caption_attribution_description: English: A measuring cup purchased in the United States circa 1980, showing both metric and U. S. Customary graduations. The bottom of the same measuring cup will be uploaded as :image:Measuring_cup_bottom.jpg. Copyright ©2006 by Daniel P. B. Smith and released under the GFDL.
context_page_description: 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 of the molten form; some glasses such as volcanic glass are naturally occurring. The most familiar, and historically the oldest, types of manufactured glass are "silicate glasses" based on the chemical compound silica, the primary constituent of sand. Soda-lime glass, containing around 70% silica, accounts for around 90% of manufactured glass. The term glass, in popular usage, is often used to refer only to this type of material, although silica-free glasses often have desirable properties for applications in modern communications technology. Some objects, such as drinking glasses and eyeglasses, are so commonly made of silicate-based glass that they are simply called by the name of the material.
  Although brittle, silicate glass is extremely durable, and many examples of glass fragments exist from early glass-making cultures. Archaeological evidence suggests glass-making dates back to at least 3,600 BCE in Mesopotamia, Egypt, or Syria.
context_section_description: Borosilicate glasses (e.g. Pyrex, Duran) typically contain 5–13% boron trioxide (B₂O₃). Borosilicate glasses have fairly low coefficients of thermal expansion (7740 Pyrex CTE is 3.25×10⁻⁶/°C as compared to about 9×10⁻⁶/°C for a typical soda-lime glass). They are, therefore, less subject to stress caused by thermal expansion and thus less vulnerable to cracking from thermal shock. They are commonly used for e.g. labware, household cookware, and sealed beam car head lamps.
caption: A Pyrex borosilicate glass measuring jug
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