Borofloat 33 vs C-Glass
Glass · grade comparison
Borofloat 33 and C-Glass are both glass grades. C-Glass is the stronger of the two: tensile strength 3,300 MPa (479 ksi) against 35 MPa (5.08 ksi) for Borofloat 33, about 94 times as much. C-Glass is the more ductile: elongation 4.8% versus 0% for Borofloat 33, and C-Glass is harder (540 HV vs 480 HV). Borofloat 33 is lighter (2.23 g/cm³ vs 2.52 g/cm³ for C-Glass) and C-Glass is stiffer (69 GPa vs 64 GPa).
Borofloat 33Choose it when weight is the constraint.
C-GlassChoose it when strength drives the design, or when the part is bent, formed or impact-loaded.
Borofloat 33 vs C-Glass: propertiesHow to read these bars
- One bar per material. A full bar is the highest value among all glass grades in the FabDigit library; each bar is drawn as a share of that.
- The better value (by the usual engineering direction) is in bold. Rows with no direction — density, thermal conductivity — have no bold.
- Values are typical room-temperature figures for the condition named on each card.
- Confirm against the certified mill or resin datasheet before design release.
How to read these bars
- One bar per material. A full bar is the highest value among all glass grades in the FabDigit library; each bar is drawn as a share of that.
- The better value (by the usual engineering direction) is in bold. Rows with no direction — density, thermal conductivity — have no bold.
- Values are typical room-temperature figures for the condition named on each card.
- Confirm against the certified mill or resin datasheet before design release.
Mechanical
Strength, stiffness, ductility and hardness at room temperature.
Elastic (Young's) Modulus
Shear Modulus
Bulk Modulus
Poisson's Ratio
Tensile Strength (Ultimate)
Elongation at Break
Flexural Strength
Shear Strength
Fracture Toughness (K_IC)
Hardness, Vickers
Hardness, Knoop
Hardness, Mohs
Same in both: Compressive Strength 1,000 MPa145 ksi
Physical
Density and transition temperatures.
Density
Refractive Index
Light Transmission
Melting Point (Solidus)
Same in both: Porosity 0%
Thermal
How each material carries heat and how hot it can run.
Thermal Conductivity
Specific Heat Capacity
Thermal Expansion (CTE, 20–100 °C)
Max Service Temperature (continuous)
Min Service Temperature
Electrical
Conductivity and insulation.
Electrical Resistivity
Dielectric Strength
Dielectric Constant (1 MHz)
Dissipation Factor (1 MHz)
Volume Resistivity
Chemical & Environmental
Corrosion and environmental resistance (0–100 scores).
Corrosion Resistance
Manufacturability
FabDigit workshop ratings (0–100 scores) — how each material behaves on the machine.
Polishability
Same in both: Machinability 12 / 100
Sustainability
Primary-production footprint per kilogram.
Embodied Energy (primary production)
Embodied Carbon (primary production)
Embodied Water
Typical Recycled Content
Common Calculations
Ratios derived from the values above.
Specific Strength (UTS / density)
Specific Stiffness (E / density)
Thermal Diffusivity
Thermal Shock Resistance Index
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.
Manufacturing and finishing
| Capability | Borofloat 33 | C-Glass |
|---|---|---|
| Default condition | Annealed Glass | — |
| Relative cost | $$ Standard | $$ Standard |
| Min. machined wall | — | — |
| Best machined surface | — | — |
Borofloat 33 vs C-Glass — frequently asked
Is C-Glass stronger than Borofloat 33?
Yes. C-Glass has a typical tensile strength of 3,300 MPa (479 ksi) against 35 MPa (5.08 ksi) for Borofloat 33 — about 94 times as much.
Which is cheaper, Borofloat 33 or C-Glass?
Both sit in the same relative cost tier ($$, standard); the part price will be decided by machining time, tolerance and quantity rather than by the material.
When should I choose Borofloat 33 over C-Glass?
Pick Borofloat 33 when weight is the constraint. Pick C-Glass when strength drives the design, or when the part is bent, formed or impact-loaded.
Ready to make it?
Upload a CAD file and FabDigit prices the part in Borofloat 33 and C-Glass 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.