What is Glass Strengthening?
Glass strengthening increases the mechanical resistance of a glass component by creating compressive stress at or near the surface. Depending on the glass material, thickness and finished-part requirements, this can be achieved through thermal treatment or chemical ion exchange.
Different strengthening routes provide different levels of impact resistance, surface quality, break behavior and dimensional capability.
We offer three primary strengthening methods:
Heat Tempered Glass
Heat tempering is used where high impact resistance, resistance to rapid temperature change and a safety-type break pattern are required.
- Surface compression: >10,000 psi
- Impact resistance: approximately 4–5× annealed glass
- Thickness range: 3–19 mm
- Part size: 2 × 2 in to 120 × 60 in
- Withstands bending and rapid temperature change
- Suitable for applications requiring fully tempered glass
Heat Strengthened Glass
Heat strengthening provides increased mechanical strength without fully tempering the glass. It is used when glass thickness, material type or cosmetic requirements make full tempering less suitable.
- Surface compression: 3,500–7,000 psi
- Impact resistance: approximately 2–3× annealed glass
- Thickness range: 2–19 mm
- Part size: 2 × 2 in to 120 × 60 in
- Better cosmetic surface than fully heat-tempered glass
- Does not produce the same full diced break pattern as fully tempered glass
Chemically Strengthened Glass
Chemical strengthening uses sodium/potassium ion exchange in a salt bath to create a highly compressed surface layer. It is particularly suitable for thin glass, display covers and parts requiring high cosmetic surface quality.
- Glass thickness: 0.210–19 mm
- Part size: from approximately 6 mm up to 50 in
- Standard strengthening cycles: 8 h or 16 h
- Modulus of rupture: 165 MPa after 8 h
- Modulus of rupture: 220 MPa after 16 h
- Impact resistance: approximately 5–6× untreated glass
- Improved bending and scratch resistance
Strengthened Glass Components We Provide
Display & Touch Cover Glass
Thin chemically strengthened cover glass for touch screens, displays and other frequently handled electronic interfaces.
Appliance & Equipment Glass
Heat-treated glass panels for appliance, food-service, machinery and industrial OEM applications.
Architectural & Fixture Glass
Tempered and strengthened glass for commercial fixtures, architectural systems and exposed glass assemblies.
Lighting & Photovoltaic Glass
Strengthened low-iron, patterned and optical glass for lighting, illumination and photovoltaic applications.
Glass Strengthening Performance & Material Compatibility
Thermal and chemical strengthening use different mechanisms to increase glass strength. Thermal processes create compressive stress by controlled heating and cooling, while chemical strengthening uses ion exchange to build a compressed surface layer without exposing thin cover glass to the same thermal cycle.
The required process depends strongly on glass composition. Some materials can be fully heat tempered, while others are better suited to heat strengthening or chemical strengthening.
- Heat tempered surface compression: >10,000 psi
- Heat strengthened surface compression: 3,500–7,000 psi
- Chemical strengthening cycles: 8 h / 16 h
- Chemical strengthening modulus of rupture: 165 / 220 MPa
- Maximum thermal-process size: 120 × 60 in
- Chemical-strengthening thickness range: 0.210–19 mm
Strengthening Features
Thermal tempering provides the greatest improvement in impact resistance among the thermal routes and is used where both mechanical strength and a safety-style break behavior are required.
Heat strengthening provides an intermediate level of mechanical improvement and is useful for glass that cannot or does not need to be fully tempered.
Chemical strengthening is suited to thinner substrates and cosmetic surfaces where high impact resistance, improved scratch resistance and minimal surface distortion are important.
Glass Materials & Process Compatibility
- Soda-Lime Glass — can be fully heat tempered and can also be chemically strengthened.
- Borofloat® Borosilicate Glass — heat strengthened rather than fully tempered because of its low thermal expansion.
- Low-Iron Optical Glass — can be fully heat tempered.
- Patterned Glass — Solite, linear, ribbed and prismatic glass can be thermally processed.
- Colored Glass — heat strengthening is used instead of full tempering.
- Non-Glare Glass — suitable for chemical strengthening.
- High-Ion-Exchange Cover Glass — suitable for chemical strengthening and thin display applications.
- AR-Coated Glass — can be thermally processed, although the high-temperature cycle may affect some AR coating systems.
Strengthened glass can also proceed through additional fabrication, printing and optical coating operations. Available post-processing includes anti-reflection coatings, ITO coatings and oleophobic surface treatments.
Applications of Strengthened Glass
Strengthened glass is used where impact resistance, thermal resistance, surface durability or safer break behavior is required from a finished glass component.
Typical Applications
- Displays & Touch Screens — chemically strengthened cover glass and integrated display protection
- Appliance & Foodservice Equipment — strengthened panels and glass components for repeated handling and thermal exposure
- Industrial OEM & Machinery — equipment panels, cab glass and protective glass components
- Fireplace & Architectural Glass — thermally processed glass for commercial fixtures and building applications
- Photovoltaic & Lighting — low-iron, patterned and strengthened glass for solar and illumination systems
- Transportation & Medical Equipment — fabricated strengthened glass for vehicle, equipment and medical interfaces
Frequently Asked Questions
Heat tempered glass provides higher surface compression and approximately 4–5 times the impact resistance of annealed glass. Heat strengthened glass provides approximately 2–3 times the impact resistance and generally offers a slightly better cosmetic surface.
Heat tempered glass is available from 3 mm to 19 mm thick.
Heat strengthened glass is available from approximately 2 mm to 19 mm thick.
Chemical strengthening is available for glass down to approximately 0.210 mm thick.
Heat tempered and heat strengthened glass can be processed up to approximately 120 × 60 in.
Chemical strengthening provides approximately 5–6 times the impact resistance of ordinary untreated glass, together with improved bending and scratch resistance.
Standard ion-exchange strengthening cycles are 8 hours or 16 hours.
Borofloat® borosilicate glass is processed through heat strengthening rather than full tempering because of its lower coefficient of thermal expansion.
Compatible AR-coated glass can be thermally processed, although the high-temperature cycle can cause crazing in some coating systems. Coating and strengthening requirements should therefore be considered together.
Yes. Surface compressive stress can be measured non-destructively using glass surface stress measurement equipment.
Glass Strengthening Capabilities
- Three Strengthening Routes — heat tempering, heat strengthening and chemical strengthening
- Thin to Thick Glass — thicknesses from 0.210 mm to 19 mm
- Large-Format Thermal Processing — parts up to 120 × 60 in
- Integrated Glass Fabrication — strengthening can be combined with fabrication and printing
- Optical Surface Options — AR, ITO and oleophobic coatings available with strengthened glass
- Stress Measurement — non-destructive surface compressive stress inspection available
Get in Touch with Our Engineers
Whether you need heat-tempered glass panels, thin chemically strengthened cover glass, or a fabricated glass component that combines strengthening, printing and optical coatings, we can configure the process around the glass material, thickness, size and finished application.