All You Need to Know About Heat-Strengthened vs Heat Soaked Glass Solutions

In the world of glass solutions for architecture and design, different types of treated glass are used based on structural, safety, and aesthetic needs.

Two specialised types of glass, heat-strengthened and heat-soaked glass, are engineered to meet demanding architectural needs. Both offer unique properties and strengths and are chosen for specific applications.

Let’s dive into these types of glass, their benefits, and common uses.

Understanding Heat-Strengthened Glass

Durability and Clarity Combined

Heat-strengthened glass (HS glass) is a type of glass that undergoes a controlled heating and cooling process, giving it strength superior to standard, annealed glass. The key lies in the cooling method used:

• During manufacturing, the glass is heated to high temperatures and then slowly cooled, a process called quenching.
• The gradual cooling creates a strong outer layer and a stable tension within, giving the heat-strengthened glass significantly higher strength than annealed glass but less than the strength of fully tempered glass.

Key Benefits:

• Enhanced Durability- Heat-strengthened glass is ideal for general glazing applications where enhanced strength is needed to resist wind loads and thermal stress.
• Aesthetic Appeal: Its clear, transparent quality makes it a favourite choice for architectural and interior design projects where aesthetics are essential.

Applications:

Heat-strengthened Glass Stands Strong in Style

• Heat-strengthened glass is popular in high-rise building facades, balustrades, and windows. Its strength and durability make it a great choice for exteriors that experience high wind loads. However, it is not used in applications which require a safety glass product.

What is Heat-Soaked Glass?

Promising Safety and Resilience

Heat-soaked glass refers to fully tempered glass that undergoes an additional heat treatment to minimise the risk of spontaneous breakage caused by NiS (Nickle sulfide) inclusions. This inclusion can sometimes expand after the glass is installed, leading to sudden breakage, which is especially undesirable in high-stress environments like tall buildings.

The heat-soak test process involves:

• Placing the tempered glass inside a heat-soak chamber at about 290°C for several hours.
• This test accelerates the expansion of NiS inclusions. Any glass with NiS inclusions breaks within the chamber, thus reducing the risk of unexpected breakage after installation.

Key Benefits:

• Enhanced Safety: The heat-soaking process minimises the chance of breakage after installation, making it suitable for public safety projects. 

Applications:

Safety comes first with Heat-Soaked Glass

• Heat-soaked glass is frequently used in facades of skyscrapers, airports, and stadiums—places where the risk of glass falling is a concern.
• This glass is also chosen in balconies, floors and canopy structures, where tempered glass strength is required with additional safety from breakage. 
• It is also used in oversized glass installations or complicated and intricate designs. 

Choosing the Right Glass

The choice between heat-strengthened and heat-soaked glass depends on the project’s specific needs and requirements:

1. For Durability with Moderate Safety Needs: Choose heat-strengthened glass, which provides adequate strength and thermal stress resistance without the higher cost associated with tempered or heat-soaked glass.
2. For High-Safety Environments: Heat-soaked glass is ideal for projects where the risk of glass breakage could have serious consequences, like in high-traffic areas or high-rise buildings.

Saint-Gobain’s glass solutions offer resilience, safety, and design flexibility tailored to the demands of today’s architectural challenges.