What is Borosilicate Glass?
In the late 19th century, German glassmaker Otto Schott first added Boric Acid to the traditional Soda lime glass composition, creating the first batches of Borosilicate glass, also known as Sodium-Borosilicate glass.
Borosilicate glass is made up of:
- 80% Silica
- 13% Boric Oxide
- 4% Sodium Oxide
- 2 – 3% Aluminium Oxide
Is Borosilicate Glass Safe?
It’s main property is that it does not expand like ordinary glass does. Due to its low coefficient of thermal expansion, it has superior thermal shock resistance. In Soda lime glass, Sodium atoms soften the glass, making it easier to shape. However, when Sodium atoms are hot, they vibrate and expand making the glass break. In Borosilicate glass, softening is achieved by adding Boron atoms, so less Sodium is needed. As a result, it expands only one-third as much as Soda lime glass. This means that even if it undergoes a sudden temperature change, it will not easily break. In the very rare and extreme case that it does break, it would crack, but it is less likely to shatter compared to traditional Soda lime glass. Borosilicate glass is so safe, that it is commonly used for household ovens and cookware. Even at high temperatures, the glass can be set on a cool counter without shattering.
It also has a high melting point of approximately 1648°C, making it more heat resistant than regular glass. It is known that above 525°C, the glass begins to soften and above 860°C, it begins to liquefy. It remains both clear and strong even when exposed to high temperatures, making it ideal for high-end stage lighting, LED lights and stroboscopes.
This glass is also known for its extremely high chemical resistance. Everything from test tubes, rods and beakers to graduated cylinders, pipettes and stopper attachments are produced from Borosilicate and used in laboratories around the world. It handles even the most volatile chemicals, always remaining intact. It can even be used for nuclear waste storage.
Borosilicate Glass Art
Artists have been heating and melting glass for centuries, mainly using a technique known as flameworking or lampworking. However, with the creation of Borosilicate glass, they are able to harness unique properties and produce larger-scale and more complex works. Due to its high thermal shock resistance, it enables artists to connect multiple components into large and intricate compositional works with greater ease. Another advantage for artists is the unique ability to be heated and manipulated in one specific. Objects can be softened or distorted by selectively heating certain areas to achieve a range of aesthetic effects. The artist will also be able to place a Borosilicate Glass rod in the flame directly without any concerns for safety. In the case of Soda lime glass, it must be slowly warmed to ensure that it wont shatter.
Borosilicate Glass Colours
Another unique facet for artists working with this glass is the striking colour palette. Striking means that the glass will change color upon reheating. Borosilicate striking colors can produce an entire range of textures and hues, simply from a single rod. The colours are repeatable and they do not burn out, as is the case with certain Soda lime colours. They are extremely versatile and can be used to produce a range of effects.