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Alumina-Lime-Silica Glass (IEC G-400) vs Borofloat 33

Glass · grade comparison

Alumina-Lime-Silica Glass (IEC G-400) and Borofloat 33 are both glass grades. Alumina-Lime-Silica Glass (IEC G-400) is the stronger of the two: tensile strength 60 MPa (8.7 ksi) against 35 MPa (5.08 ksi) for Borofloat 33, about 71% more. Alumina-Lime-Silica Glass (IEC G-400) is harder — 620 HV against 480 HV for Borofloat 33 — which matters for wear surfaces and threads. Borofloat 33 is lighter (2.23 g/cm³ vs 2.6 g/cm³ for Alumina-Lime-Silica Glass (IEC G-400)) and Alumina-Lime-Silica Glass (IEC G-400) is stiffer (87 GPa vs 64 GPa). On the shop floor, Borofloat 33 sits in a lower cost tier (standard, $$) than Alumina-Lime-Silica Glass (IEC G-400) (premium, $$$).

Alumina-Lime-Silica Glass (IEC G-400)Choose it when strength drives the design, or when surface hardness matters.

Borofloat 33Choose it when weight is the constraint, or when cost is the deciding factor.

Alumina-Lime-Silica Glass (IEC G-400) vs Borofloat 33: properties

Alumina-Lime-Silica Glass (IEC G-400)Borofloat 33

Mechanical

Strength, stiffness, ductility and hardness at room temperature.

Elastic (Young's) Modulus

87 GPa12.6 Msi
64 GPa9.3 Msi

Shear Modulus

35 GPa5.1 Msi
26.7 GPa3.9 Msi

Bulk Modulus

57 GPa8.3 Msi
36 GPa5.2 Msi

Poisson's Ratio

0.25
0.2

Tensile Strength (Ultimate)

60 MPa8.7 ksi
35 MPa5.1 ksi

Flexural Strength

90 MPa13.1 ksi
25 MPa3.6 ksi

Shear Strength

55 MPa8 ksi
25 MPa3.6 ksi

Fracture Toughness (K_IC)

0.8 MPa·√m0.73 ksi·√in
0.77 MPa·√m0.7 ksi·√in

Hardness, Vickers

620 HV
480 HV

Hardness, Knoop

600 HK
480 HK

Hardness, Mohs

6.5
6

Same in both: Elongation at Break 0% · Compressive Strength 1,000 MPa145 ksi

Physical

Density and transition temperatures.

Density

2.6 g/cm³0.09 lb/in³
2.23 g/cm³0.08 lb/in³

Refractive Index

1.53
1.471

Light Transmission

90%
92%

Same in both: Porosity 0%

Thermal

How each material carries heat and how hot it can run.

Specific Heat Capacity

840 J/kg·K0.2 BTU/lb·°F
830 J/kg·K0.2 BTU/lb·°F

Thermal Expansion (CTE, 20–100 °C)

4.6 µm/m·K2.6 µin/in·°F
3.3 µm/m·K1.8 µin/in·°F

Max Service Temperature (continuous)

650°C1,202 °F
450°C842 °F

Min Service Temperature

-190°C-310 °F
-196°C-321 °F

Same in both: Thermal Conductivity 1.2 W/m·K0.69 BTU/hr·ft·°F

Electrical

Conductivity and insulation.

Dielectric Constant (1 MHz)

6.3
4.6

Dissipation Factor (1 MHz)

0.004
0.0037

Same in both: Electrical Resistivity 1×10¹³ Ω·m3.94×10²⁰ µΩ·in · Dielectric Strength 30 kV/mm762 V/mil · Volume Resistivity 1×10¹⁵ Ω·cm

Chemical & Environmental

Corrosion and environmental resistance (0–100 scores).

Corrosion Resistance

90 / 100
92 / 100

Manufacturability

FabDigit workshop ratings (0–100 scores) — how each material behaves on the machine.

Polishability

96 / 100
95 / 100

Same in both: Machinability 12 / 100

Sustainability

Primary-production footprint per kilogram.

Embodied Carbon (primary production)

1.6 kg CO₂/kg
1.8 kg CO₂/kg

Typical Recycled Content

5%
10%

Same in both: Embodied Energy (primary production) 25 MJ/kg10,748 BTU/lb · Embodied Water 15 L/kg1.8 gal/lb

Common Calculations

Ratios derived from the values above.

Specific Strength (UTS / density)

23 kN·m/kg
16 kN·m/kg

Specific Stiffness (E / density)

33.5 MN·m/kg
28.7 MN·m/kg

Thermal Diffusivity

0.5 mm²/s
0.6 mm²/s

Same in both: Thermal Shock Resistance Index 0

Strength versus weight

Yield strength against density for every glass grade in the FabDigit library; the compared grades are highlighted. Up and left is stronger for its weight.

501002005002.533.5Density (g/cm³)Yield strength (MPa) — log scaleBorofloat 33

Manufacturing and finishing

CapabilityAlumina-Lime-Silica Glass (IEC G-400)Borofloat 33
Default condition—Annealed Glass
Relative cost$$$ Premium$$ Standard
Min. machined wall——
Best machined surface——

Alumina-Lime-Silica Glass (IEC G-400) vs Borofloat 33 — frequently asked

Is Alumina-Lime-Silica Glass (IEC G-400) stronger than Borofloat 33?

Yes. Alumina-Lime-Silica Glass (IEC G-400) has a typical tensile strength of 60 MPa (8.7 ksi) against 35 MPa (5.08 ksi) for Borofloat 33 — about 71% more.

Which is cheaper, Alumina-Lime-Silica Glass (IEC G-400) or Borofloat 33?

Borofloat 33 is the lower-cost material: it sits in the standard tier ($$) while Alumina-Lime-Silica Glass (IEC G-400) is premium ($$$). Part price depends far more on geometry, tolerance and quantity than on raw stock — upload a CAD file for a live quote.

When should I choose Alumina-Lime-Silica Glass (IEC G-400) over Borofloat 33?

Pick Alumina-Lime-Silica Glass (IEC G-400) when strength drives the design, or when surface hardness matters. Pick Borofloat 33 when weight is the constraint, or when cost is the deciding factor.

Ready to make it?

Upload a CAD file and FabDigit prices the part in Alumina-Lime-Silica Glass (IEC G-400) and Borofloat 33 side by side — material, machining time, tolerance and finish in one quote. Certified material data ships with the order on request.

Typical handbook values for the conditions named above, normalised for comparison. Hardness on non-Brinell scales is converted approximately for charting only. Request certified data with your order for design-critical properties.