Properties of Glass Materials

In general, glass is a hard and brittle substance that is usually transparent or translucent. It may be comprised of a fusion of sand, soda, lime, or other materials. The most common glass forming process heats the raw materials until they become molten liquid, then rapidly cools the material to create hardened glass.

Swift Glass is an industry leader in glass fabrication. We stock materials from a wide variety of glass manufacturers, such as:

  • Vitro
  • GE

Each material we stock is carefully selected for its physical properties and unique performance capabilities.

Some of our offerings include:

  • Different varieties of sight glass for use across a broad spectrum of industries
  • SCHOTT BOROFLOAT® Glass, which is utilized in a variety of lighting, optical, and glass wafer applications for its beneficial properties, which include excellent mechanical strength, resistance to extreme temperatures, and exceptional transparency
  • Silica float glass for windows and displays
  • Pyrex® (discontinued) for use in both low- and high-pressure environments
  • Vycor® (discontinued) for optical applications that operate under highly pressurized, high temperature conditions

Composition and Properties of Glass Materials

Relative to many other materials, glass possesses high hardness values. However, most types of glass tend to be naturally brittle, which makes them vulnerable to breakage or fracturing in applications where impacts, pressures, or stresses are present. In order to eliminate this inherent brittleness, engineers and manufacturers must thoroughly process glass according to optimal strengthening/tempering protocols.

Glass types can be divided by their mechanical and thermal properties to determine which applications they will most suitably match. The following properties of glass materials are important to consider during the selection process:


Viscosity is a measure of a liquid’s internal friction, or resistance to flow. When glass is in its molten liquid state, most processing techniques that manufacturers employ require its viscosity to be within a certain range at a specific temperature. This is referred to as the working point—or the level of viscosity at which manufacturers can shape the glass by means of blowing, pressing, or other operations.


Many glasses—depending on their specific composition—boast a high theoretical structural strength. However, certain practical considerations tend to significantly reduce their workable strength. For instance, the following factors may lead to sub-optimal strength in the glass type:

  • Flaws or defects on the glass surface
  • Thermal stresses introduced during a rapid cooling process
  • The introduction of tiny crystals into the surface through annealing

Flaws on the surface of glass can act as focal points for stress. Concentrated stress introduced by a load that exerts more pressure than the theoretical strength of the glass can bear will usually cause a fracture or breakage. Thus, flaws or defects on the glass’s surface greatly reduce the fracture strength of the product. Nevertheless, manufacturers can eliminate or prevent the occurrences of these surface flaws and cracks through precision and care in the manufacturing process.

Glasses vary as to their level and type of strength. For example:

  • Tempered soda lime glass—also known as Type-III glass—has high mechanical strength.
  • Aluminosilicate glass has high compressive strength, which makes it ideal for use in solar cells, cover glass and touch displays, among other applications.
  • Borosilicate glass boasts exceptional structural strength and is frequently used in glass tubing, medical devices and devices for space exploration.

Thermal Expansion Behavior

Glass tends to expand with increasing temperatures. The thermal expansion curve for glass provides three crucial properties to engineers and manufacturers for the glass in question:

  • Thermal expansion coefficient measures the rate of expansion with temperature.
  • Transition temperature sees the onset of viscoelastic behavior and a period of sudden expansion.

Glasses vary as to their thermal expansion behavior and their related workability. For example, silica glass has a low coefficient of thermal expansion, and is therefore more difficult to shape or distort relative to other glass types.

Glass Material Applications

Glass as a primary source material is used across an extremely broad range of applications and industries. The following is a list of some common glass material applications:

  • Glass is vital to the production of semiconductor wafers. Glass wafers act as a carrier substrate, facilitating the safe handling of thinner and more delicate silicone materials.
  • Oven doors and stove tops are typically comprised of glass material.
  • The biotech sector relies on borosilicate glass wafers for a variety of medical devices because of its clear optical transparency and resistance to high temperatures, radiation, and energy. Glass wafers also act as a carrier substrate to protect silicone devices used in nanotechnology.
  • MEMs and Electronics. TV, computer, and smartphone screens are all made from glass. Engineers use special glass types for touchscreen displays. Glass wafers are also used as substrate carriers and wafer packaging for sensitive components in microelectronic mechanical systems (MEMs) and electronics.
  • Automotive and transportation. Windshields, headlights, and backlights make use of specific glass materials. Glass is also used as a source material for many lightweight, reinforced structural components found in automobiles, airliners, helicopters, ocean cruisers, and other vehicles.
  • Medical technology. As an example of the use of glass in the medical field, X-ray machines contain glass.
  • Renewable energy. Low-iron or extra-clear glass has extremely limited light reflection properties, which makes it an excellent fit for solar cell covers. Maximum amounts of sunlight can come through the glass cover and help charge the solar battery.
  • Integrated Circuit (IC) Packaging. Glass vias (TGV) and wafer-level glass capping (WLC) are used to ICs against corrosion or impacts to ensure optimal functionality. They serve a dual purpose of holding contacts to external circuits in place.

Partnering with Swift Glass

Glass is useful for many applications across many industries. However, it is important that companies utilize the glass material best suited to the desired application.

For nearly a century, Swift Glass has made its mark as an industry leader in high-quality custom glass fabrication. We have the expertise to meet the unique needs of clients in many industries and you can be sure that we will deliver superior products at reasonable prices.

If you’d like to learn more about which glass material is most suitable for your desired application, download our free Glass Material Properties Chart today, or reach out to us for a free quote on your next project.

Download Now: Glass Material Properties Chart

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