Why homogenization treatment needed for tempered glass?
May 18, 2026
Tempered glass is a type of prestressed glass. To enhance its strength, we usually use chemical or physical methods to create compressive stress on the glass surface. This way, when the glass is subjected to external forces, the surface stress is offset first, thereby improving the glass's impact resistance.
Heat soak treatment, also known as homogenization treatment or commonly referred to as "controlled detonation", involves heating tempered glass to 290℃±10℃ and holding it at that temperature for a certain period. This process promotes the rapid phase transformation of nickel sulfide in the tempered glass, causing defective or potentially self-exploding tempered glass to break artificially in the factory's heat soak furnace. In turn, this reduces the risk of tempered glass self-exploding after installation and use. This method generally uses hot air as the heating medium; overseas, it is called "Heat Soak Test" (HST for short), which translates directly to heat soak treatment.
Why Is Homogenization Treatment Necessary for Tempered Glass?
The main purpose of homogenization treatment for tempered glass is to reduce its self-explosion rate. The national standard GB 15763.2-2005 explains "self-explosion" of tempered glass: when nickel sulfide crystals appear in the tensile stress zone of tempered glass, crystal transformation will cause self-explosion. That's why we usually use a glass tempering furnace to perform homogenization treatment on glass, which improves the safety of glass in use.
The Process of Homogenization Treatment
The homogenization treatment process for tempered glass includes three stages: heating, heat preservation, and cooling-similar to the process of tempering raw glass sheets.
1. Heating Stage
Heating starts from the ambient temperature of the glass and stops when all glass reaches 280℃. The surface temperature of the glass must not exceed 320℃, and the time when the glass surface exceeds 300℃ should be shortened as much as possible. This requires uniform heating.
2. Heat Preservation Stage
Once all glass reaches 280℃, heat preservation starts. The process lasts for at least two hours, maintaining the glass surface temperature within the range of 290℃±10℃.
3. Cooling Stage
After heat preservation is completed, the cooling stage begins to lower the glass to room temperature. When the temperature inside the furnace drops to 70℃, the furnace door can be opened to end the cooling process and take out the glass.
