Borosilicate

Glass is a specialized form of glass that uses boric acid as a component in its

fabrication. The result of the addition of the element boron is a type of glass that

is very resistant to thermal shock and exhibits a much lower coefficient of thermal

expansion than that of common silicate glass. In this article, a review of

borosilicate glass will be presented, including its development, properties, and

uses.
Development of Borosilicate Glass
Back in 1882, a German chemist named Otto Schott was interested in experimenting

with ways to create glass that had the ability to withstand sudden changes in

temperature or exposure to uneven temperatures without shattering. In that year, he

made the discovery that ushered in the creation of the

Borosilicate Glass Tube. Schott discovered that the addition of the

element Boron to the glass fabrication process resulted in a heat-resistant form of

glass.
Later work by chemists W.C. Taylor and Eugene Sullivan at Corning Glass refined

the efforts of Otto Schott and expanded the temperature resistant properties of

borosilicate glass. As a result of these innovations, customized glass fabrication

grew, where there is now over a million different formulations of glass that can be

customized for specific product needs by enhancing the desired physical and

mechanical properties of glass.
Perhaps the most well-known application for borosilicate glass grew from further

research at Corning Glass. After joining the company in 1914, physicist Jesse

Littleton was given the task of testing and evaluating the physical properties of the

newly created glass formulation. After his wife’s ceramic casserole dish

accidentally broke, she suggested that perhaps this newly developed heat resistant

glass might prove to be a useful product for baking. After she tested the notion by

baking a cake in a sample glass container that Littleton had brought home, a new use

for Borosilicate Glass Rod was born – glass cookware. Corning Glass

introduced a line of products known as Pyrex?[1], which was for many years of its

manufacturing run produced using borosilicate glass.
Properties of Borosilicate Glass
Borosilicate glass is generally chemically resistant, but perhaps its most

remarkable physical property is its low coefficient of thermal expansion, which

explains why the glass can resist shattering under sudden rapid changes in

temperature. Glass generally is a poor conductor of heat, so when you take hot glass

and immerse it in cold water, the exterior of the glass cools rapidly while the

interior does not. The stresses caused by the temperature differential cause the

glass to shatter.
With Borosilicate Glass Solar Vacuum Tube

, the addition of boric acid (H3BO3) to the formulation results in a glass that

has a low coefficient of thermal expansion, which means that when the glass is heated

or cooled, it does not expand or contract very much. This dimensional stability is

what enables borosilicate glass to be capable of withstanding rapid and extreme

temperature changes without cracking.
The chemical composition of borosilicate glass typically consists of around 81%

silicon dioxide (SiO2) and 13% boron trioxide (B2O3) with lesser concentrations of

sodium oxide and aluminum oxide. (Note that the concentrations of boric oxide can

vary, 5-13% is typical). The element Boron is what provides the glass with its

dimensional stability so that the material doesn’t shrink or grow as the temperature

to which it is exposed changes.
Applications of Borosilicate Glass
The initial problem that was attempting to be solved at the time that Otto Schott

began experimenting with glass formulations was to create a glass that could stand up

against extreme temperature exposure. For example, the glass that was used in

lanterns at that time would end up shattering or cracking in rainy conditions because

the cold rain on the exterior surface of the glass caused a large temperature

gradient when compared with the temperature of the hot interior face.
Once borosilicate Pharmaceutical Glass became available, its applications became

immediately apparent. Some of the common uses for borosilicate glass include:
Laboratory glassware
Scientific lenses and hot mirrors
Bakeware and cookware
Laboratory glassware
The high dimensional stability and ability to tolerate exposure to different

temperatures at the same time make borosilicate glass a natural material choice from

which to create laboratory Borosilicate Glassware, also called labware. Petri dishes,

microscope slides, Borosilicate Bottle and Cups, beakers,

flasks, test tubes, funnels, and measuring instruments such as graduated cylinders

are all common examples. Besides the favorable thermal properties, borosilicate glass

is very resistant and non-reactive to most chemicals.
Scientific lenses and hot mirrors
Borosilicate glass can be molded into high precision optical components such as

lenses for use in telescopes and other precision optical devices. The low coefficient

of thermal expansion for borosilicate glass means that the optical properties of the

lenses will be stable over changes in temperature as the glass lens will not

significantly change its dimensions. The glass is also ideal for use in hot mirrors

that reflect infrared light.
Bakeware and cookware
Among its first and most common uses is in the creation of household cookware and

bakeware. The thermal properties of

Kitchen Glassware allow it to be transported from a hot oven to a

cool countertop without fear of cracking or shattering. It is also used in products

such as measuring cups and is safe for use in microwave ovens and dishwashers.