Glass Strengthening
Comparison of glass tempering processes
Chemical Tempering | Physical Tempering | Physical Semi-Tempering
The strength and safety of glass do not depend on its thickness, but rather on its internal stress structure.
Saida Glass provides high-performance, customized glass solutions for various industries through a variety of tempering processes.
1. Chemical Tempering
Process Principle: Glass undergoes ion exchange in high-temperature molten salt, where sodium ions (Na⁺) on the surface are replaced by potassium ions (K⁺).
Through the ion volume difference, a high-pressure stress layer is formed on the surface.
Performance Advantages:
Surface strength increased by 3–5 times
Nearly no thermal deformation, high dimensional accuracy
Can be further processed after tempering, such as cutting, drilling, and screen printing.
Thickness range: 0.3 – 3 mm
Minimum size: ≈ 10 × 10 mm
Maximum size: ≤ 600 × 600 mm
Features: Suitable for ultra-thin, small sizes, high precision, virtually no deformation
Typical Applications:
● Mobile phone cover glass
● Automotive display glass
● Optical instrument glass
● Ultra-thin functional glass
2. Physical Tempering (Fully Tempered / Air-Cooled Tempering)
Process Principle: After the glass is heated to near its softening point, forced air cooling rapidly cools the surface layer, creating strong compressive stress on the surface and tensile stress internally.
Performance Advantages:
● 3-5 times increase in bending and impact resistance
● Emerges as blunt-angled particles, ensuring high safety
● Widely applicable to medium-thick glass
Thickness range: 3 – 19 mm
Minimum size: ≥ 100 × 100 mm
Maximum size: ≤ 2400 × 3600 mm
Features: Suitable for medium to large-sized glass, high safety
Typical Applications:
● Architectural doors and windows
● Appliance panels
● Shower enclosure glass
● Industrial protective glass
3. Physically Tempered Glass (Heat-Strengthened Glass)
Process Principle: Same heating method as fully tempered glass, but uses a gentler cooling rate to control surface stress levels.
Performance Advantages:
● Strength higher than ordinary glass, lower than fully tempered glass
● Significantly better flatness than physically tempered glass
● Stable appearance, less prone to warping
Thickness range: 3 – 12 mm
Minimum size: ≥ 150 × 150 mm
Maximum size: ≤ 2400 × 3600 mm
Features: Balanced strength and flatness, stable appearance
Typical Applications:
● Architectural curtain walls
● Furniture tabletops
● Interior decoration
● Glass for display and partitions
Glass in different fracture states
Broken Pattern of Regular (Annealed) Glass
Shatters into large, sharp, jagged shards, posing a significant safety hazard.
Heat-Strengthened (Physical Semi-Tempered) Glass
Shatters into large, irregular fragments with some small pieces; edges may be sharp; safety is higher than annealed but lower than fully tempered glass.
Fully Tempered (Physical) Glass
Breaks into small, relatively uniform, blunt fragments, minimizing the potential for serious injury; surface compressive stress is lower than chemical tempered glass.
Chemical Tempered (Chemically Strengthened) Glass
Typically cracks in a spiderweb pattern while remaining largely intact, significantly reducing the risk of sharp projectiles; offers the highest safety and is extremely resistant to impact and thermal stress.
How to choose the right tempering process for your product?
✓ For ultra-thin, high-precision, or optical performance → Chemical tempering
✓ For safety and cost-effectiveness → Physical tempering
✓ For appearance and flatness → Physical semi-tempering
Saida Glass can customize the optimal tempering solution for you based on dimensions, tolerances, safety levels, and application environment.